CPU-Level Ransomware: The New Nightmare Hiding in Your Hardware?

1. Executive Summary: The Low-Down on CPU-Level Threats – What You Can’t Afford to Ignore

Alright, let’s cut to the chase. We’re seeing a nasty new trend in cyber threats: attacks diving deep into the guts of your computers, right down to the CPU. Think of it – vulnerabilities that let bad actors load their own malicious microcode. This isn’t your run-of-the-mill malware; this is about fundamentally hijacking how your processor works. We’re zeroing in on recent bombshells from AMD’s Zen architecture – think CVE-2024-56161 and CVE-2024-36347. The scary part? If an attacker already has admin rights on a machine (and let’s be honest, getting those is often the first win for them), these flaws let them rewrite the CPU’s playbook.

The real kicker? We’ve seen proof-of-concept (PoC) ransomware built to exploit this. Imagine ransomware that bypasses almost every traditional security defense because it’s running at the hardware level. This isn’t just fancy ideas; it’s a demonstrated risk. And it’s not a niche problem. AMD’s Zen 1 all the way through the shiny new Zen 5 chips are in the crosshairs – that’s everything from your gaming rig to your workhorse servers.

And if you think it’s going to stop at AMD, well we’ve got bad news for you.  Could someone please check on Apple?

A Jailbreak for CPUs? Lessons from the iPhone

This situation echoes the checkm8 era of iPhone jailbreaks, where a hardware-based bootrom vulnerability left entire generations of iPhones permanently jailbreakable. Apple couldn’t patch the flaw via software—it was etched into the silicon. Similarly, the AMD Zen microcode flaws reside in foundational CPU behavior, specifically how microcode signatures are verified. If that flawed logic is baked into immutable ROM, even BIOS updates can’t fully fix it.

The implication? A generation of AMD CPUs may be permanently susceptible to malicious microcode injection if an attacker gains the right privileges. With enough refinement, attackers could craft reliable “CPU jailbreaks” that persist despite firmware updates—especially if they can subvert hardware protections or modify firmware loaders. While the security community isn’t there yet, the parallels are striking, and the long-term concern is clear: if we can’t fully revoke trust in compromised microcode loaders, this becomes a hardware trust crisis, not just a patching problem.

So, what’s the damage? System integrity and data confidentiality go out the window. Malicious microcode can mess with super-privileged parts of your system like the System Management Mode (SMM) and even break AMD’s own Secure Encrypted Virtualization (SEV-SNP) meant to protect your virtual machines. Now, the malicious microcode itself usually vanishes on a reboot. But here’s the terrifying combo: if an attacker chains this with firmware (UEFI/BIOS) hacking, they can make their malware persistent. They could use the CPU flaw to disable hardware write protections for your firmware, then plant malware that reloads their nasty microcode every single time you boot up. That means the infection could survive an OS reinstall, maybe even swapping out some hardware.

The big caveat: attackers need local admin rights first, for now.   These CPU flaws aren’t usually the way they break in. But once they’re in your network and escalate to admin on a box, these vulnerabilities become a golden ticket for deep, stealthy persistence. This screams for defense-in-depth, locking down privileged access like your life depends on it, and working from an “assume breach” mindset.  Its not going to be long before a bad guy handy with AI coders figures out a way to embed an exploit for this into a maliciously crafted image or a blob URI 

SEE RELATED ARTICLE: 

Blob URI Phishing: The Sneaky Threat Slipping Past Your Defenses

 

Your game plan? Prioritize BIOS/firmware patching – yes, it’s a pain, but it’s non-negotiable. Beef up your privileged access management to stop attackers from getting those admin keys in the first place. And start looking into advanced detection, like hardware integrity monitoring and behavioral anomaly detection, because your standard tools might be blind to this. Sectors like healthcare and higher education? You’re on high alert. Your sprawling IT, valuable data, and often-creaky legacy systems make you prime targets. Time to get your defenses in order. This report digs into the nitty-gritty and gives you practical, actionable advice.

2. The New Bad Guys on the Block: CPU and Firmware Ransomware

The threat landscape never sleeps, and the latest evolution is a doozy: attacks targeting the very foundations of your computers – CPU microcode and system firmware. This isn’t your garden-variety malware that plays in the operating system or application sandbox. Nope, these nasties aim to corrupt the root of trust, the very core of your devices.

Let’s break it down. Microcode is like a secret language inside your CPU, low-level instructions telling the processor how to handle the fancier machine code. CPU makers like AMD and Intel push out microcode updates (usually via your BIOS/UEFI or OS) to fix bugs, patch security holes, or boost performance. Then there’s firmware – think UEFI or the older BIOS. That’s the first bit of software that kicks into gear when you hit the power button, waking up all the hardware and handing off to your operating system.

So, why are firmware and microcode suddenly hot property for sophisticated attackers?

• Stealth Mode On Steroids: Malware at this level? It’s practically invisible to most of your standard security software – AV, EDR, OS integrity checkers. They all assume the OS and hardware are playing fair.
• The Unkillable Cockroach (Persistence): This is the holy grail for attackers. Firmware infections can survive OS reinstalls, new hard drives, and reboots. While a malicious microcode loaded via a bug like AMD’s Zen flaw isn’t persistent on its own (it needs a reload), if an attacker can tweak your firmware to reload it at boot? Game over. That infection is there to stay.
• Ultimate Power: Compromise the CPU’s microcode or the system’s boot firmware, and attackers own that device, plain and simple. They can mess with anything, bypass any security, and grab any data.

Rapid7’s Christiaan Beek threw down the gauntlet. Inspired by the AMD Zen microcode bug, he cooked up a PoC ransomware that works by mucking with the CPU’s microcode. This CPU-level nasty loads its malicious code directly at the hardware level. Beek called it a “worst case scenario” that could “bypass every freaking traditional technology we have out there.” The chilling implication: even if you swap out motherboards or storage, if the ransomware is embedded deep enough in firmware that keeps reloading it, it’s not going anywhere.

Now, hardware-based rootkits aren’t brand new – we’ve seen horrors like CosmicStrand and LoJax targeting UEFI firmware. But Beek’s work specifically shows a ransomware payload running via CPU microcode. And it’s not just researchers; the bad guys are interested too. Leaked chats from the Conti ransomware gang back in 2022 showed them scheming about UEFI-based ransomware that would stick around even after an OS reinstall.

When vulnerability details like the AMD Zen CPU flaws go public, and we know threat actors are eyeing these low-level vectors, it’s a recipe for trouble. Security research proves these attacks are feasible, and threat actor chatter shows they’re motivated. Responsible researchers don’t unleash their PoCs, but the knowledge that it’s possible, combined with public vulnerability info, can fast-track development for well-funded adversaries. This is why rapid, coordinated patching and proactive defense are absolutely critical when these deep-level hardware vulnerabilities surface.

3. Under the Hood: What’s Really Wrong with AMD’s Zen CPUs? (CVE-2024-56161 & CVE-2024-36347 / AMD-SB-7033)

So, what’s the actual glitch letting attackers mess with AMD’s Zen processors at such a fundamental level? We’re looking at a couple of key vulnerabilities, primarily CVE-2024-56161 and CVE-2024-36347 (covered in AMD’s Security Bulletin AMD-SB-7033). The core of the problem? A faulty bouncer at the microcode update door – specifically, improper verification of cryptographic signatures.

The Core Problem: Shoddy Signature Checks

Think of microcode as firmware for your CPU. Normally, any updates to this microcode must be cryptographically signed by AMD. This signature is like a seal of authenticity, proving the update is legit and hasn’t been tampered with. These vulnerabilities mean an attacker who has already snagged local admin rights (think kernel-level or Ring 0 access) can basically forge this signature or bypass the check altogether. This lets them load their own malicious, unsigned microcode.

• CVE-2024-56161: This one’s described as an “improper signature verification in the AMD CPU ROM microcode patch loader.” If an attacker has local admin, they can load malicious CPU microcode. The big worry here is for confidential virtual machines (VMs) running under AMD’s Secure Encrypted Virtualization with Secure Nested Paging (SEV-SNP) – this flaw could blow their confidentiality and integrity wide open. It’s rated 7.2 (High) on the CVSSv3 scale. SOCRadar gives it a slightly lower immediate risk score but flags it as “In The Wild,” meaning exploits might be circulating. The weakness is categorized as CWE-347: Improper Verification of Cryptographic Signature.
• AMD-SB-7033 (and CVE-2024-36347): AMD’s own bulletin calls this the “AMD Microcode Signature Verification Vulnerability.” They pin it on a “weakness in signature verification algorithm.” Other reports get more specific, pointing to a “weak hashing algorithm (AES-CMAC).” Google researchers, who found this, confirmed the CPU uses an insecure hash function for checking microcode update signatures. This let them cook up their own malicious patches that the CPU happily accepted. Their PoC even changed how the RDRAND instruction (used for generating random numbers, super important for crypto) works, making it always spit out ‘4’. CVE-2024-36347, as listed in AMD’s bulletin, gets a CVSS score of 6.4 (Medium).

An “insecure hash function” or a busted signature check is a massive design flaw. Crypto is the bedrock here. If the hash function is weak, attackers can create malicious stuff that looks legit to the CPU. Google’s PoC proves it’s not just theory. This has a domino effect: any security feature relying on the CPU’s microcode integrity, like SEV-SNP, is now at risk if the microcode itself can be poisoned. It’s a brutal reminder that rock-solid crypto design in hardware is non-negotiable.

Who’s Affected? Pretty Much Everyone with AMD Zen

This isn’t some obscure bug in a niche product. It hits a massive range of AMD processors built on the Zen architecture. Initially, we heard Zen 1 through Zen 4 were vulnerable. That includes:

• EPYC server chips: 7001 (Naples), 7002 (Rome), 7003 (Milan/Milan-X), and 9004 (Genoa/Genoa-X/Bergamo/Siena).
• Ryzen desktop and mobile processors across those generations.

Then, the plot thickened: the vulnerability extends to the latest Zen 5 architecture too. That means Ryzen 9000 series desktops, EPYC 9005 (Turin) server CPUs, and Ryzen AI 300 mobile processors are also on the list. So, from your home PC to high-performance computing clusters and enterprise servers, this bug is lurking.

How the Microcode Gets Hijacked

CPUs boot with a base microcode baked into their internal ROM. Updates can be loaded by the system firmware (BIOS/UEFI) early on, or later by the OS, to fix issues or improve things. These updates are temporarily stashed in special RAM inside the CPU (SRAM). The vulnerability lets an attacker with the right privileges slip in a malicious microcode patch, and because of the faulty signature check, the CPU just runs it.

The Potential Fallout: It’s Bad

Successfully loading malicious microcode can lead to a world of hurt:

• Your CPU Lies: The CPU can be tricked into executing instructions incorrectly or doing completely different things than it’s supposed to. Google’s RDRAND hack is a perfect example.
• Privileged Data Exposed: Sensitive data being crunched by the CPU, even in its most protected modes, could be stolen or altered.
• SMM Compromised: The System Management Mode (SMM) is an ultra-privileged CPU mode used for low-level hardware stuff and security functions. If SMM is compromised, pretty much all OS-level security is toast.
• AMD SEV-SNP Shattered: This tech is designed to shield VMs by encrypting their memory and ensuring integrity, even from a dodgy hypervisor. Malicious microcode can rip these protections apart, giving attackers access to supposedly secure VMs. This is a nightmare for cloud providers and anyone relying on confidential computing.

CVE-2024-56161 vs. CVE-2024-36347: What’s the Diff?

Both CVEs point to the same core AMD microcode signature mess, but there are nuances. Ubuntu’s advisory notes CVE-2024-36347 is “somewhat related” to CVE-2024-56161. The latter seems to focus more on the AMD SEV-SNP firmware aspect within the amd64-microcode package, while CVE-2024-36347 is tied to changes in the Linux kernel’s AMD SEV firmware. AMD’s bulletin (AMD-SB-7033), which covers the broader signature vulnerability across many product lines, gives CVE-2024-36347 a CVSS of 6.4 (Medium). CVE-2024-56161, often cited with a CVSS of 7.2 (High), is more directly linked to the SEV-SNP impact. Think of CVE-2024-36347 as the umbrella for the core signature flaw, and CVE-2024-56161 as a specific, nasty consequence, especially for SEV-SNP. The bottom line for both: bad signature checks let a privileged attacker load bad microcode.

Table 3.1: AMD Microcode Vulnerabilities – The Cheat Sheet

CVE ID / AMD ID	Gist	Main Impact	CVSS Score (Source)	Affected CPUs (Broadly)
CVE-2024-56161	Bad signature check in CPU ROM microcode patch loader (SEV-SNP in focus)	SEV-SNP guest confidentiality/integrity loss, system compromise	7.2 (High) (SOCRadar, NVD)	AMD Zen 1-5 (especially EPYC with SEV-SNP)
CVE-2024-36347 (AMD-SB-7033)	Weak microcode signature check algorithm lets attacker load arbitrary patch	x86 execution integrity loss, privileged data confidentiality/integrity loss, SMM compromise	6.4 (Medium) (AMD)	AMD Zen 1-5 (EPYC, Ryzen, Threadripper)

4. How Bad Is It Really? Attack Scenarios & Your Actual Risk

Okay, so we know these AMD Zen microcode vulnerabilities are serious. But what does an actual attack look like, and how likely is it to hit you? Let’s get real about the risk profile.

The “You Must Be Admin First” Rule

Here’s the crucial bit: to exploit these AMD microcode flaws, the attacker must already have administrator or kernel-level privileges (Ring 0) on your system. This isn’t usually how they break in from the outside. Instead, it’s a super-weapon for an attacker who’s already pwned a machine.

How do they get those admin rights in the first place? The usual suspects:

• Popping other software holes in your OS or apps (like that nasty Windows Common Log File System Driver bug, CVE-2025-29824, that was making headlines).
• Good old phishing to snatch admin credentials.
• Exploiting sloppy security configurations or access controls.
• Insider threats – someone with legit admin access going rogue.
• Hitting vulnerabilities in high-privilege software. Remember hackers using a flaw in Genshin Impact’s kernel-level anti-cheat to get Ring 0 access? That’s the kind of foothold that could then let them play with these microcode vulnerabilities.

Once they’re admin, then they can unleash the AMD microcode attack.

Remote vs. Physical Access & User Clicks

The microcode exploit itself is a local job, needing privileged code to run on the target CPU. But the initial admin compromise? That can totally happen remotely. Physical access could also pave the way for privilege escalation.

No user clicks are needed for the microcode loading part once admin rights are in hand. The initial compromise that gets those rights, though, might involve a user clicking a bad link or opening a booby-trapped file.

Proof-of-Concepts: It’s Not Just Theory

We’re not just spitballing here. Researchers have built working PoCs:

• Google’s RDRAND Hack: Google researchers proved they could load unsigned microcode and forge signatures. Their PoC famously changed the RDRAND CPU instruction (vital for random numbers in crypto) to always return ‘4’. They tested this on AMD EPYC server CPUs and AMD Ryzen 9 desktops.
• Rapid7’s CPU Ransomware: Christiaan Beek from Rapid7, inspired by the AMD Zen bug, built a PoC ransomware that works by loading malicious microcode at the hardware level. This showed how ransomware could dodge traditional security and be incredibly persistent. Thankfully, Beek isn’t releasing this PoC into the wild.

The Exploit Chain: How Deep Does the Rabbit Hole Go?

Loading arbitrary microcode is bad. Here’s how it can play out:

• Total System Pwnage: Changing fundamental CPU behavior? That’s deep compromise.
• Escalating Privileges (Even Further): While admin rights are the entry ticket, malicious microcode could let attackers go even deeper – subverting System Management Mode (SMM), compromising hypervisors, or shattering AMD SEV-SNP security. This is like getting “Ring -1” or “Ring -2” access, beyond even the OS kernel.
• Persistence: The Real Monster (When Chained): This is where it gets truly terrifying.

• Microcode loaded via this vulnerability is “hot-loaded” – it’s volatile and disappears on reboot. The CPU usually resets to its factory microcode unless the BIOS/UEFI or OS loads a new patch during boot.
• The massive risk is when an attacker, with kernel control and the ability to load arbitrary microcode, uses this power to attack and modify the system’s firmware (UEFI/BIOS). The malicious microcode isn’t just for a temporary CPU tweak; it becomes a tool to achieve almost permanent, stealthy persistence by messing with the boot process itself.
• An attacker with this level of control might:

1. Exploit flaws in firmware update mechanisms.
2. Try to disable SPI flash write protections. Modern systems have hardware and firmware locks to stop unauthorized writes to the SPI flash chip holding the UEFI/BIOS. These are often managed by SMM code or OS drivers. Malicious microcode could directly manipulate the CPU’s interaction with the SPI controller or SMM, or subvert firmware update tool integrity checks below the OS level, potentially bypassing these locks. Research shows even legit, signed (but flawed) UEFI drivers can be exploited to disable SPI flash protections; malicious microcode could offer a more direct, stealthy path.
3. If they disable write protections, they could plant a persistent loader in the UEFI firmware. This loader would then reload the malicious microcode every time the system boots, before or during OS loading.
4. This attack chain results in malware that survives OS reinstalls, hard drive swaps, and maybe even some BIOS update attempts if the malicious firmware can also interfere with the update process. This is exactly what advanced firmware rootkits like LoJax do, and what ransomware gangs like Conti dream about.

• Data Theft/Manipulation: Malicious microcode could subtly change calculations, leak sensitive data being processed by the CPU (bypassing OS-level encryption), or break crypto by, say, messing with random number generation or directly attacking encryption algorithms.

Weaponized Exploits: Are They Out There?

This is a bit murky:

• SOCRadar has tagged CVE-2024-56161 as “In The Wild,” suggesting exploits are circulating or active attacks have been seen.
• AMD, in their AMD-SB-7033 bulletin (covering the conditions for CVE-2024-56161 via CVE-2024-36347), said they hadn’t received any reports of this attack happening in any system when they published it.

This difference could be due to varying visibility or definitions of “in the wild.” SOCRadar might be seeing PoC activity, limited targeted attacks not yet widely known, or research. Google’s “deliberate partial-disclosure” of the AMD microcode flaw also hints at a serious level of concern. Regardless, with detailed vulnerability info and successful PoCs public, the threat is credible, and weaponization by sophisticated actors is plausible.

The admin access prerequisite means your first line of defense is stopping that initial compromise. But the potential for an already-privileged attacker to use these CPU-level flaws for ultimate persistence and stealth makes them a severe threat, especially from APTs and high-end ransomware crews.

5. MITRE ATT&CK® Mapping: How This Fits into the Hacker Playbook

So, where does “malicious CPU microcode loading” fit into the grand scheme of hacker tactics, as defined by the MITRE ATT&CK® framework? Good question. It’s not a standalone technique yet, but its capabilities and goals map to several existing tactics and techniques. Understanding this is key for security teams to fold this threat into their existing ATT&CK-based models, detection, and defense plans. These attacks are nasty because they operate at such a low level, often sidestepping assumptions made by higher-level defenses.

Here’s how exploiting CPU microcode vulnerabilities like the AMD Zen flaw, especially when it leads to malicious microcode execution or firmware-based ransomware, lines up with ATT&CK:

• TA0003: Persistence (This is a big one)

• T1542: Pre-OS Boot: If malicious microcode gets loaded by compromised firmware (like a hacked UEFI/BIOS), it’s running before your main OS even wakes up.

• T1542.001: System Firmware: Bang on. Attackers modify system firmware for persistence that laughs off reboots and OS reinstalls. Loading malicious microcode via compromised firmware is a super-sophisticated way to do this. The bad microcode, or a loader for it, becomes a permanent fixture.

• T1547: Boot or Logon Autostart Execution: If the malicious microcode is loaded by a compromised OS component that runs early during boot or logon.

• T1547.006: Kernel Modules and Extensions: An attacker who already owns the kernel could use a malicious kernel module to trigger the malicious microcode load at startup. The microcode then unlocks even more advanced evil.

• TA0002: Execution

• The act of a privileged process (like a malicious kernel driver or an admin-level tool) kicking off the load of malicious microcode? That’s execution.
• And if the malicious microcode itself is designed to change how CPU instructions run to achieve a specific malicious goal (like bypassing security checks), that’s a deeply embedded, highly privileged form of execution.

• TA0004: Privilege Escalation

• Yes, attackers need admin/kernel privileges to exploit the AMD Zen microcode vulnerability initially. But the power granted by the subsequently loaded malicious microcode can be an escalation to a privilege level beyond the typical OS kernel. Think compromising System Management Mode (SMM), subverting hypervisors, or breaking AMD SEV-SNP. This effectively gives the attacker “Ring -1” or “Ring -2” control, making even the OS kernel look like a junior admin.

• TA0005: Defense Evasion

• Malware at the microcode level is inherently sneaky.
• T1562: Impair Defenses: Malicious microcode could potentially mess with hardware-based security features or interfere with software security tools by changing how the CPU processes certain instructions or reports its status.

• T1562.001: Disable or Modify Tools: Could directly interfere with your security toolkit.

• T1070: Indicator Removal on Host: By controlling CPU operations, malicious microcode might subtly alter logs or system behavior to hide itself or other malware.
• Rootkit/Bootkit: The whole MO, especially if they achieve persistence through firmware modification, screams rootkit/bootkit. These aim to hide malicious activity and maintain control. Malicious microcode is like the ultimate deep-level rootkit component.

• TA0009: Collection / TA0010: Exfiltration / TA0040: Impact

• Malicious microcode can be a direct enabler for these later-stage attack goals. For example, it could:

• Subtly leak sensitive data by changing how the CPU handles data during crypto or memory access.
• Corrupt data or mess with critical calculations.
• Enable ransomware encryption at the hardware level, as Christiaan Beek’s PoC showed, making data recovery incredibly difficult.

Think of malicious microcode loading not just as one technique, but as a powerful “meta-capability.” It can supercharge other ATT&CK techniques. For example, to hit System Firmware (T1542.001), attackers might traditionally exploit a firmware update flaw or use an OS tool if protections are weak. But if they can first load malicious microcode, they might be able to disable SPI flash write protections directly from the CPU. This makes the follow-up firmware modification for persistence much easier and could bypass many standard OS or SMM-based controls. Defenders need to realize that known ATT&CK techniques could be executed with unprecedented stealth and privilege if an adversary can leverage a CPU microcode vulnerability.

Table 5.1: MITRE ATT&CK® Mapping – CPU Microcode & Firmware Attacks

ATT&CK Tactic ID & Name	ATT&CK Technique ID & Name	How It Relates to CPU Microcode/Firmware Attacks
TA0003: Persistence	T1542: Pre-OS Boot	Malicious microcode loaded by compromised firmware runs before the OS.
	T1542.001: System Firmware	Hacking UEFI/BIOS to persistently load malicious microcode or other bad boot code. Malicious microcode can help make this firmware hack happen.
	T1547.006: Kernel Modules & Extensions	A malicious kernel module (needs prior kernel compromise) could be the vehicle to load the malicious microcode.
TA0002: Execution	N/A (Implied by other techniques)	The act of loading microcode by a privileged process; malicious microcode changing how instructions execute.
TA0004: Privilege Escalation	N/A (Implied by impact)	Owning SMM, SEV-SNP, or the hypervisor from kernel-level is an escalation to deeper hardware privilege.
TA0005: Defense Evasion	T1562: Impair Defenses	Malicious microcode could disable hardware/software defenses or manipulate them.
	T1222: File and Directory Permissions Modification	Indirectly, if malicious microcode helps bypass protections to modify firmware storage.
	Rootkit/Bootkit (Concept)	The overall behavior, especially with firmware persistence, is classic rootkit/bootkit stuff, but at a super-privileged level.
TA0040: Impact	T1486: Data Encrypted for Impact	The CPU-level ransomware PoC shows direct impact via microcode.
	T1499: Endpoint Denial of Service	Malicious microcode could potentially make the CPU or system unstable or unusable.

6. Fighting Back: Mitigation, Detection, and Hardening Your Defenses

Alright, so these CPU microcode and firmware threats are scary. How do we fight back? It’s going to take a layered defense – think proactive patching, iron-clad access controls, smart detection, and a clear understanding of what your hardware security features can (and can’t) do.

Job #1: Firmware/BIOS Updates – Patch, Patch, Patch!

The most direct way to shut down these AMD Zen microcode signature vulnerabilities (CVE-2024-56161, CVE-2024-36347) is to slap on updated system firmware (BIOS/UEFI) that includes patched microcode.

• AMD’s Part: AMD cooks up updated Platform Initialization (PI) firmware, which includes new AGESA (AMD Generic Encapsulated Software Architecture) versions, and hands it off to the Original Equipment Manufacturers (OEMs).
• OEMs’ Part: Your motherboard vendors and system makers (Dell, HP, Lenovo, etc.) then take this, bake it into specific BIOS/UEFI updates for their gear, and push it out to you.
• Your Critical Action: You must find vulnerable systems and get these BIOS updates installed. This is ground zero for fixing the signature verification flaw. We’re talking AGESA versions like ComboAM5PI 1.2.0.3c for some Zen 5 systems and various specific PI versions for EPYC and older Ryzen chips.
• The Catch: Firmware patching is often a bigger pain than OS or app patching. Think manual updates, OEM validation delays for every single model, and users being (understandably) nervous about flashing their BIOS. This means there’s often a big window of vulnerability even after patches are technically out.

Compensating Controls: If You Can’t Patch Immediately

Since these AMD flaws need admin rights to be exploited, beefing up your defenses around those privileged accounts is a crucial backup plan:

• Lock Down Privileges: Enforce the Principle of Least Privilege (PoLP) like it’s gospel. Regular users should not have admin rights. Period.
• Restrict Local Admin Access: Keep the number of local admin accounts to an absolute minimum and watch them like a hawk.
• Spot Privilege Escalation: Have ways to detect and investigate if lower-privileged accounts or processes try to grab admin rights.

Detection: Finding Needles in a Haystack

Spotting malicious microcode loading or execution is tough because it’s so low-level. But here are some angles:

• Watch for Rogue Microcode Loading:

• Version Checks: Regularly check the loaded microcode version against known good, patched versions from AMD and your OEM. On Linux, /proc/cpuinfo can help; on Windows, check specific registry keys. But a smart attacker might try to spoof this.
• Log Monitoring: Keep an eye on system and security logs for any weird or unauthorized microcode update events. This might need some specialized logging.
• AMD SEV-SNP Attestation: If you’re using SEV-SNP, monitor attestation reports for integrity issues. Weirdness here could signal a compromise.
• Beefed-Up Security Monitoring: Use security monitoring systems to spot suspicious activities that might be linked to attempts to load microcode or abuse related privileges.

• Look for Weird CPU Behavior / Performance Dips:

• Big, unexplained changes in CPU performance, random system crashes, or bizarre behavior in CPU-heavy tasks could theoretically point to malicious microcode. But attackers will aim for stealth, so this isn’t a reliable standalone. AI-driven anomaly detection for resource use is an emerging field here.

• Firmware Integrity Checks:

• Use specialized tools (like Eclypsium) to scan and verify your system firmware (UEFI/BIOS) integrity and spot known vulnerable microcode.
• Regularly scan firmware integrity and compare measurements against known good baselines.

• Hardware-Level Attestation (Measured Boot & Remote Attestation):

• TPM-based Measured Boot: A Trusted Platform Module (TPM) can record crypto-hashes of boot components (firmware, bootloaders, critical OS files) into Platform Configuration Registers (PCRs).
• Remote Attestation: These PCR values can be sent to a trusted remote server for verification against known good values. If malicious microcode is loaded by compromised firmware, the firmware measurement would change, and remote attestation could catch it on the next boot.
• Limitations: This all depends on the integrity of the measurement process itself. Super-sophisticated attacks might try to subvert the TPM or feed it fake measurements, though that’s a complex hack.

• Research into Micro-Architectural Attack Detection: Academics are digging into detecting anomalies from micro-architectural attacks (like µSpectre, which hits microcode branch mispredictions). While not directly for spotting malicious microcode loading, this research might give us tools to identify weird CPU behavior that points to microcode manipulation.

What About Hardware Security Features (Secure Boot, TPMs, Intel Boot Guard / AMD Platform Secure Boot)?

These techs are designed to create a hardware root of trust and protect boot integrity:

• Secure Boot: Ensures only authentically signed OS bootloaders and drivers run. It checks them against signatures in a firmware database (DB) and uses a revocation list (DBX) for known bad ones.
• Intel Boot Guard / AMD Platform Secure Boot (PSB): These vendor-specific features aim to verify the integrity of the initial UEFI firmware stages against crypto signatures or hashes, often anchored to keys fused into the CPU or chipset. This creates a hardware-backed root of trust for the firmware itself.
• TPM (Trusted Platform Module): As mentioned, TPMs help with measured boot by securely storing hashes. They can also “seal” data (like disk encryption keys) to specific PCR values, meaning the data only gets unsealed if the system boots into a trusted state.

Now, if an attacker already has OS admin/kernel privileges and then tries to load malicious microcode, these hardware security features are put under serious pressure. Secure Boot and Boot Guard/PSB mainly protect against unauthorized code running before the OS loads or against firmware modification by an attacker without high OS privileges. Once a privileged OS is running, it can legitimately ask for a microcode update. The AMD Zen vulnerability means this requested update can be malicious.

The million-dollar question: can malicious microcode, once loaded by the compromised OS, retroactively break this trust chain or disable these hardware protections for future boots or to enable persistent firmware modification? Theoretically, yes, it’s a concern:

• Malicious microcode with direct CPU control could try to mess with TPM measurement reporting or manipulate hardware registers controlling SPI flash write protections, potentially bypassing SMM-based or firmware locks.
• If the malicious microcode can enable persistent firmware modification (e.g., by disabling SPI flash write protections), it could plant code that subverts Secure Boot or the TPM measurements on subsequent boots.
• However, these hardware security features make achieving such persistent firmware compromise much harder. The attacker’s malicious microcode would need to actively find and exploit weaknesses in how these hardware defenses are implemented.

NIST Special Publication 800-193 (“Platform Firmware Resiliency Guidelines”) offers a framework for designing systems that can protect, detect, and recover from firmware attacks, emphasizing Roots of Trust for Update (RTU), Detection (RTD), and Recovery (RTRec). Following these guidelines is key to building tougher platforms.

Endpoint Monitoring & IDS/IPS

While your EDR might struggle to directly see malicious microcode running, it’s vital for catching the initial admin compromise or any weird system calls if the malicious microcode interacts with the OS in odd ways. IDS/IPS are unlikely to spot the microcode load itself but might catch C2 traffic if the resulting malware phones home.

Train Your People (Users and Admins)

• Ongoing training on spotting phishing, social engineering, and the importance of strong, unique passwords helps prevent the initial breaches that give attackers admin access.
• IT admins need to know how critical timely BIOS/firmware updates are and be trained on secure firmware update procedures.
• Push secure system configuration practices across the board.

Table 6.1: CPU-Level Threats – Your Defense Playbook

Defense Category	Specific Action	Key Gotchas/Limitations
Patch Management	Apply BIOS/UEFI Firmware Updates	THE main fix. Relies on OEM release schedules; can be slow. Often manual. Risk of instability with some BIOS updates.
Access Control	Enforce Principle of Least Privilege (PoLP)	Critical, as admin rights are a prerequisite.
	Restrict & Monitor Local Admin Accounts	Shrinks the attack surface for that initial compromise.
Microcode Monitoring	Check Loaded Microcode Version	Basic check; advanced malware might spoof it. Needs an up-to-date “good version” list.
	Monitor for Unauthorized Microcode Load Events	Might need specialized logging and SIEM magic.
Firmware Security	Firmware Integrity Scanning (e.g., Eclypsium)	Can spot known vulnerable firmware/microcode and unauthorized mods.
	Hardware Attestation (TPM Measured/Secure Boot)	Catches unauthorized changes to boot components on next boot. Relies on measurement/reporting integrity.
Behavioral Detection	Monitor for Anomalous CPU/System Behavior	Can be noisy; attackers aim for stealth. May need advanced analytics/ML.
	Enhanced Security Monitoring for Privileged Ops	Focus on catching admin privilege abuse that could lead to microcode loading.
Training & Awareness	User Training (Phishing, Social Engineering)	Stops those initial compromise vectors.
	Admin Training (Secure Firmware Updates, Secure Configs)	Ensures proper application of fixes and secure practices.
System Hardening	Network Segmentation	Limits the blast radius if a system gets popped.
	Disable Unnecessary Hardware Features/Interfaces	Reduces the overall attack surface.

7. Sector Spotlight: Higher Education – A Prime Target for Deep Hacks

Higher education institutions are a unique beast when it comes to cybersecurity, and unfortunately, that often means they’re uniquely vulnerable to advanced threats like CPU-level and firmware-based attacks. Several factors crank up their risk profile:

Why Higher Ed is in the Crosshairs:

• Juicy Targets: Universities are constantly under attack, and ransomware loves them. They’re sitting on mountains of sensitive data: student and faculty PII, financial records, and incredibly valuable intellectual property (IP) from research.
• Sprawling & Diverse IT Mess: Campuses are a chaotic mix of devices – many personally owned by students and faculty (hello, BYOD!) – connecting from everywhere. This massive, decentralized footprint is an attacker’s playground and a nightmare for consistent security.
• Crown Jewels of IP: University research cooks up cutting-edge IP. Nation-states and corporate spies are drooling over it.
• Stretched Thin IT Resources: Let’s be real, many higher ed institutions are running on tight IT security budgets with overworked staff. This makes it tough to roll out and maintain solid security, including the often-painful process of firmware patching across a zoo of hardware.
• Legacy System Graveyard: Budget woes and long hardware lifecycles mean universities often have a ton of ancient systems and gear with minimal or non-existent security support. These dinosaurs are unlikely to get firmware updates for bugs like the AMD Zen flaw.
• Ransomware Magnets: The education sector had the dubious honor of reporting the highest rate of ransomware attacks in 2023. A whopping 79% of higher ed institutions admitted to being hit, up from 64% the year before.

Add to this the often-decentralized IT management where departments or research labs run their own shows, plus a culture of “research freedom.” This can lead to lax security on specialized research gear, creating more chances for attackers to find unpatched systems or snag local admin rights on machines that often need such privileges for complex experiments. A CPU-level attack on a critical, one-of-a-kind research system holding irreplaceable data? Devastating.

The Impact: When CPU/Firmware Ransomware Hits Campus:

• Data Annihilation: Years of research, student records, sensitive admin info, institutional financials – all potentially gone forever if systems are locked or wiped at the CPU or firmware level.
• Wallet-Crushing Costs: The average ransomware recovery cost for higher ed was a cool $1.06 million. CPU-level attacks could be even pricier, potentially needing hardware replacement and super-complex recovery.
• Campus Shutdown: These attacks could cripple essential IT services: learning systems, online courses, registration, research clusters, admin functions – all down for the count, potentially for ages. Recoveries of one to three months aren’t unheard of.
• Reputation Ruin: A major cyberattack, especially a deep hardware compromise, torches trust with students, faculty, alumni, donors, and research funders.

Higher Ed’s Defense Playbook:

• Aggressive, Centralized Firmware Patching: Get a clear inventory of all hardware, especially AMD Zen-based systems. Prioritize and enforce BIOS/firmware updates, particularly on systems handling sensitive research, student data, and critical admin functions.
• Serious Network Segmentation: Isolate critical research networks, admin systems, student networks, and especially those creaky legacy systems you can’t easily patch. This can stop attackers from moving laterally and limit the damage.
• Lock Down Endpoints (All of Them): Deploy advanced endpoint protection on all university-owned gear and, where you can, BYOD devices hitting your network. Focus on solutions that leverage hardware-enabled security.
• Iron-Clad Privileged Access Management (PAM): Since admin rights are the key to exploiting these AMD microcode flaws, get hardcore about least privilege. Slap MFA on all admin access and watch those accounts like a hawk.
• Drill Digital Literacy: Regular cybersecurity awareness for everyone – students, faculty, staff. Hammer home how to spot phishing, avoid malware, and practice good cyber hygiene.
• Incident Response Plans for This Scenario: Your IR plans need to be ready for firmware and hardware-level compromises. Think different recovery strategies, potential hardware replacement, and specialized forensics.
• Deal with Legacy Systems (Strategically): Identify and prioritize replacing or super-isolating outdated systems that won’t get firmware patches.
• Bulletproof Backups: Make sure critical data (research, student records) is backed up regularly to offline, immutable storage. And test your recovery processes.
• Balance Research Freedom with Security: Foster innovation, yes, but provide secure, centrally managed research environments or specialized IT support to lock down unique research platforms and ensure they meet baseline security and patching standards.

By getting serious about these tailored strategies, higher education can build much-needed resilience against these deep-diving hardware threats.

8. Sector Spotlight: Healthcare – Code Blue for CPU Attacks

The healthcare sector is staring down a uniquely terrifying set of risks from CPU-level and firmware-based attacks. Why? Because it’s a complex web of interconnected medical devices, holds ultra-sensitive patient data, and any disruption can directly impact patient safety. This isn’t just about data loss; it’s about lives.

Healthcare’s Unique Vulnerabilities:

• The IoMT (Internet of Medical Things) Maze: Think infusion pumps, patient monitors, MRI machines, surgical robots – a massive array of devices often running on embedded CPUs with firmware that’s a nightmare to update. Many are legacy systems, designed long before anyone was seriously thinking about cyberattacks on this scale.
• Patient Data (ePHI) – A Hacker’s Goldmine: Electronic Protected Health Information is worth a fortune on the black market and is heavily regulated (HIPAA in the US, GDPR in Europe). Breaches mean massive fines and shattered patient trust.
• Direct Threat to Patient Safety & Hospital Ops: Unlike other sectors, a cyberattack that messes with medical devices or critical hospital systems can have immediate, life-or-death consequences.
• Legacy System Overload: Hospitals are often packed with old medical devices and IT systems running unsupported OS versions and ancient firmware. These are riddled with unpatched, known vulnerabilities.
• Interconnected Chaos: Medical devices are increasingly networked. One compromised IoMT device can be a backdoor for attackers to hit the entire hospital network, taking down countless other systems.

The “unpatchable” or “rarely patched” nature of many medical devices is a massive headache. Manufacturer support cycles end, replacement is costly, FDA recertification after software/firmware changes is a beast, and some embedded systems just weren’t built for frequent updates. If the CPUs in these devices (say, AMD Zen-based embedded chips) have the microcode vulnerability, they’re unlikely to get the timely BIOS/firmware fixes available for general IT gear. An attacker who gets local or network-adjacent access to exploit such a flaw on a critical medical device could cause serious patient harm. Remediation might mean yanking the device from service, or even replacing it. And how do they get that initial access? By hitting known vulns on the device’s often-outdated OS or via a malicious insider.

The Nightmare Scenario: CPU/Firmware Ransomware in a Hospital:

• Direct Harm to Patients: Malicious microcode could subtly (or not so subtly) change how a medical device works. Imagine an infusion pump delivering the wrong dose, a patient monitor showing false vitals, diagnostic equipment failing, or life-support systems going dark.
• Critical Systems Down, Services Halted: Ransomware locking down EHR systems, PACS, lab systems, or vital medical devices can bring a hospital to its knees, delaying treatments and forcing patient diversions.
• Data Breach & Integrity Catastrophe: It’s not just about theft. If an attacker with deep system control maliciously alters patient records (blood type, allergies, meds), the consequences for patient care are unthinkable.
• Insane Remediation Costs & Downtime: If a medical device’s CPU or firmware is hit by a persistent threat, standard fixes like wiping and reinstalling software won’t cut it. The device might be out of action for ages, need specialized (and maybe unavailable) decontamination, or have to be replaced entirely. Think massive costs and operational chaos.

Healthcare’s Defense Strategy – A Prescription for Security:

• Aggressive Medical Device Security Management:

• Know Your Devices: Maintain a detailed inventory of all medical devices – make, model, CPU type (if you can find it), firmware/software versions, network connections.
• Patch Like Lives Depend On It (Because They Do): Work with manufacturers on firmware updates and security patches. Prioritize based on device criticality and vulnerability severity.
• Segment and Isolate: Use strong network segmentation to isolate medical devices, especially legacy and critical care gear, from the main hospital network and the internet. Only allow essential communication.
• Virtual Patching for the Unpatchable: For devices you can’t directly patch, use network-based security controls or host-based agents (if they support it) to block known exploits.

• Beef Up Endpoint Protection (Clinical & Admin Systems): Ensure all workstations, servers, and other IT endpoints have advanced security that can stop malware, ransomware, and fileless attacks.
• Embrace Zero Trust: Implement a “Never Trust, Always Verify” model. This means strict access controls, MFA for everyone and everything, and micro-segmentation.
• Advanced Threat Detection & Response: Deploy tools that can monitor network traffic and device behavior for anomalies. Develop incident response plans specifically for attacks targeting medical devices and critical infrastructure.
• Secure Procurement – Buy Smart: When getting new medical devices, grill vendors on their security features, commitment to timely updates, and their overall security development lifecycle.
• Constant Staff Training: Regular cybersecurity training for everyone – clinicians, IT, admin staff. Cover phishing, password hygiene, secure device handling, and reporting suspicious activity.
• Bulletproof Business Continuity/Disaster Recovery (BCDR): BCDR plans must cover widespread cyberattacks, including firmware-level compromises of critical systems and medical devices. Have manual override procedures and plans for operating during extended IT blackouts.
• Share Intel: Participate in healthcare ISACs to stay updated on threats and best practices.

The unique dangers in healthcare demand a defense-in-depth strategy that accepts some critical components, like embedded CPUs in medical devices, might be unpatchable for fundamental flaws. This makes those compensating controls even more vital.

9. How Urgent Is This? Real-World Exploits, Patch Status, and Severity

Okay, let’s talk brass tacks. How worried should you be right now about these AMD Zen microcode vulnerabilities? We need to look at active exploitation, patch availability and adoption, and how severe the security gurus rate these things.

Are Attackers Already Using This? It’s Complicated.

There’s a bit of a mixed message on active exploitation:

• CVE-2024-56161: SOCRadar, a threat intel provider, has this one tagged as being exploited “In The Wild.” That usually means they’ve seen the exploit being used or PoC code is actively circulating.
• AMD-SB-7033 (covering CVE-2024-36347): AMD, in their official security bulletin, said that at the time of publication, they hadn’t “received any reports of this attack occurring in any system.”

Why the difference?

• Different Definitions/Visibility: “In The Wild” can mean anything from actual attacks to researchers playing with PoCs, or maybe super-limited targeted attacks that AMD hasn’t confirmed yet.
• Reporting Lag: It can take time for initial detections by security firms to become official, widely reported vendor confirmations.
• PoC Nature: The PoCs from Google and Christiaan Beek were for research and weren’t publicly released for bad guys to use. But the detailed vulnerability info itself could give other actors ideas.

Google’s “deliberate partial-disclosure” of the AMD microcode flaw also signals that the security research community is taking this very seriously. Given how bad a successful exploit could be, even the potential for active exploitation should light a fire under you.

Known Incidents: So Far, So (Relatively) Quiet

As of now, there are no specific, publicly confirmed major incidents where CPU-level ransomware has successfully used these exact AMD Zen microcode vulnerabilities (CVE-2024-56161 or CVE-2024-36347) against organizations. The buzz is mostly around the potential shown by the vulnerabilities and the researcher PoCs. It’s more about a scary future risk than a widespread current onslaught using this specific vector.

The Nitty-Gritty: CVE Numbers and Severity

• CVE-2024-56161:

• CVSSv3 Score: 7.2 (High).
• Mainly linked to: Impact on AMD SEV-SNP environments, loss of confidentiality and integrity.
• CWE: CWE-347 (Improper Verification of Cryptographic Signature).

• CVE-2024-36347 (from AMD Security Bulletin AMD-SB-7033):

• CVSSv3 Score: 6.4 (Medium) as rated by AMD.
• Mainly linked to: The broader microcode signature verification flaw across AMD Zen 1 to Zen 5.
• Potential Impact: Messing with x86 instruction execution, compromising data in privileged CPU contexts, and SMM execution environment compromise. Some security folks argue it should be “Critical” if SMM compromise is factored in.

For context, Intel isn’t immune to CPU issues either, with recent disclosures about vulnerabilities in their indirect branch predictors (like CVE-2024-43420, CVE-2025-20623, CVE-2024-45332) potentially leading to info leaks. And OS-level privilege escalation bugs like CVE-2025-29824 (that Windows Common Log File System Driver flaw reported as actively exploited) are relevant because they show how attackers get the admin rights needed to then exploit CPU flaws.

Patch Status: AGESA/Firmware Updates (as of May 2025)

The main fix for these AMD bugs is updating your system BIOS/UEFI with new firmware that includes patched microcode and revised AGESA code.

• AMD to OEMs: AMD started shipping updated PI firmware to OEMs between January and March 2025.

• Examples: ComboAM5PI 1.0.0.a (around Jan 7, 2025), ComboAM4v2PI 1.2.0.E (around Jan 22, 2025), and TurinPI 1.0.0.44 (around Mar 4, 2025) are some of the mitigating versions.

• OEM BIOS Rollout: Motherboard vendors and system manufacturers started pushing out BIOS updates with these newer AGESA versions from late April 2025. For instance, AGESA ComboAM5PI 1.2.0.3C, which tackles the Zen 5 vulnerability, started showing up in BIOS updates around then.

• MSI was reportedly one of the first with BIOS updates featuring AGESA 1.2.0.3C for some 800-series motherboards.
• Dell also pushed a bunch of BIOS updates for Alienware, Inspiron, Vostro, and Precision lines with fixes around March 5-7, 2025.

• The Patching Lag Problem: Here’s the rub. There’s always a delay between AMD giving updated code to OEMs and those OEMs validating, integrating, and releasing BIOS updates for every specific product. This can take weeks or months, leaving systems vulnerable even after a fix is technically out.

• Plus, these deep hardware fixes aren’t usually delivered via automatic OS updates. Users or IT admins have to proactively hunt them down and apply them.
• End-user behavior doesn’t help either. Some folks, even tech-savvy ones, delay BIOS updates, worried about instability or new bugs.

This “patching paradox” – where the most critical flaws often need the most complex and potentially risky patching (BIOS updates) – means the window of exposure can be wider for these types of bugs compared to typical software vulnerabilities. The reliance on OEMs and the manual nature of many firmware updates lead to patchy patch adoption. This is especially worrying for older systems that might not get BIOS updates from their manufacturers anymore.

10. The Bottom Line: Proactive Defense in a World of Evolving Hardware Threats

The rise of CPU-level vulnerabilities, like the AMD Zen microcode mess, and the chilling concept of firmware-based ransomware, mark a serious shift in the cybersecurity game. These threats aren’t just scratching the surface; they’re burrowing into the very foundation of our computers, moving past the usual OS and application battlegrounds to hit the core hardware and firmware. The AMD Zen flaws (CVE-2024-56161 and CVE-2024-36347 / AMD-SB-7033) are a brutal wake-up call: deep flaws in CPU architecture or its update mechanisms can be turned into super-weapons by attackers who’ve already got admin rights, leading to catastrophic system compromise.

This whole situation hammers home a few key defensive truths:

• Defense in Depth Isn’t Optional: No single security layer, software or hardware, is a silver bullet. You need multiple layers to stand a chance.
• Patch Management Must Be Aggressive & Comprehensive: The main fix for these AMD bugs is firmware (BIOS/UEFI) updates. Yes, firmware patching is a pain, but organizations have to get good at it and deploy updates promptly.
• Lock Down Privileged Access: Since these attacks often need prior admin compromise, controlling and monitoring privileged accounts is absolutely critical to stop attackers from getting the keys to the kingdom.
• Assume You’re Already Breached: The potential for stealthy, deep-level compromise means you need an “assume breach” mindset. Don’t just focus on prevention; invest in advanced detection and have robust incident response plans ready for hardware-level nightmares.
• Verify Your Hardware’s Integrity: Tech like TPM-based measured boot, remote attestation, and specialized firmware integrity scanning tools are becoming non-negotiable for checking if your hardware and firmware stack can actually be trusted.

Looking ahead, expect more of this. Security researchers will keep finding holes in hardware and microcode from all CPU vendors. And you can bet sophisticated attackers will keep honing their skills to exploit these flaws, chasing the ultimate stealth and persistence that firmware and CPU-level compromises offer. The lines between hardware and software security are blurring fast, demanding a more holistic, integrated approach to cybersecurity.

The cybersecurity arms race is clearly descending into the silicon and firmware. As OS and application defenses get better, attackers are logically digging deeper, looking for layers where security might be weaker or where a compromise gives them a bigger strategic win. This slide from app-level malware to kernel-mode rootkits, then to UEFI/BIOS bootkits, and now to potential CPU microcode manipulation, shows a clear pattern: adversaries always seek more fundamental control. This means our defenses have to evolve to cover these deeper layers too. Organizations can’t just treat hardware and firmware as unchangeable “black boxes” anymore. A real security strategy has to explicitly include ways to secure, monitor, and validate these foundational bits.

This is a call to action. Security teams need to be vigilant. We need sustained investment in advanced security tech that can tackle hardware-level threats. And we need closer collaboration between hardware vendors, OS developers, and the wider security community. Plus, secure development lifecycles need to be baked into how firmware and hardware components are designed and made from day one, with robust crypto and thorough security validation. Only by being proactive and working together can we hope to stay ahead of the bad guys in this deep, dark, evolving threat landscape.

11. Your Action Plan: Key Takeaways for Security Briefings & Bulletins

Here’s what you need to communicate to your teams and leadership about CPU-level vulnerabilities, the AMD Zen microcode situation, and the looming threat of firmware-based ransomware. These are your talking points for security briefings and internal alerts.

• The Threat is Real (And It’s Deep): CPU-level vulnerabilities, like those in AMD’s Zen architecture (CVE-2024-56161, CVE-2024-36347), are no joke. If an attacker already has admin/kernel privileges, these flaws let them load malicious microcode. This can totally change how a CPU behaves. We’ve even seen proof-of-concept CPU-level ransomware. This is a new, dangerous frontier for super-stealthy, ultra-persistent malware.
• Admin Privileges: The Golden Key for Attackers: Crucially, these specific AMD microcode attacks aren’t how attackers first break in. They need to have already compromised the system and gained administrator or kernel privileges. So, job one is still protecting those high-privilege accounts and stopping initial breaches (phishing, software exploits, etc.).
• Firmware Persistence: The Attacker’s Endgame: Malicious microcode loaded via these vulnerabilities usually isn’t persistent on its own (it vanishes on reboot). The real nightmare is when an attacker uses this CPU-level access to then hack the system’s firmware (UEFI/BIOS). By planting a loader in the firmware, they can reload their malicious microcode every single boot. That means an infection that’s virtually undetectable and permanent, surviving OS reinstalls and even hard drive swaps.
• Patching is Paramount (But It’s a Pain): The main and most direct fix is applying BIOS/UEFI firmware updates from your hardware vendors (OEMs). These updates contain patched microcode from AMD. You must identify affected systems and get these updates rolled out. But be warned: there’s often a big delay between AMD releasing fixes to OEMs and you actually getting BIOS updates. Plus, firmware updates can be tricky to manage at scale.
• Your Traditional AV/EDR Might Be Flying Blind: Malware operating at the CPU microcode level or buried deep in system firmware can often sneak past traditional OS-based security tools (antivirus, EDR). These tools generally assume the OS and underlying hardware are trustworthy and behaving predictably.
• Key Questions Your Org Needs to Answer NOW:

• What’s our current process for tracking and deploying critical BIOS/UEFI firmware updates for all relevant AMD-based systems (servers, desktops, laptops)? Is it timely?
• How solid are our privileged access management (PAM) controls? How well are we monitoring the creation, modification, and use of admin accounts?
• Do we have any tools or methods right now to check system firmware integrity or spot weird hardware behavior that might signal a low-level compromise?
• Are our incident response plans ready for threats that stick around even after an OS reinstall or hard drive replacement? Do we even have a playbook for suspected firmware compromise?

• Top 3-5 Immediate Actions to Get Started On:

1. Hunt Down Vulnerable AMD Systems: Inventory all your AMD Zen-based systems. Check them against AMD’s security advisories (especially AMD-SB-7033) and OEM announcements to see their current BIOS/AGESA versions and flag those needing updates.
2. Prioritize and Push Firmware Patches: Make a plan and execute it. Update firmware on all affected systems, hitting your most critical assets first (servers with sensitive data, critical infrastructure controls, exec workstations).
3. Review and Harden Privileged Access: Get serious about locking down admin credentials. Enforce the Principle of Least Privilege religiously, slap Multi-Factor Authentication (MFA) on all admin access, and boost monitoring for any shady activity around privileged accounts.
4. Educate Your Tech Teams: Make sure your IT and security folks fully understand this threat vector, its potential impact, the prerequisites for exploitation, and why firmware hygiene is non-negotiable.
5. Explore Advanced Detection & Integrity Checks: If you’re not doing it already, start looking into solutions for firmware integrity scanning, hardware-level attestation (using TPMs and Secure Boot), and behavioral anomaly detection that might give you a fighting chance against low-level system compromise.

Appendix

Table A1: Affected AMD Products and Mitigating Firmware Versions (Illustrative Summary based on AMD-SB-7033 and related information)

(Heads Up: This table is a summary. Always check the latest official AMD Security Bulletins and your specific OEM advisories for the most current and detailed info for your gear.)

AMD Product Family	Codename(s)	Platform(s)	Minimum Mitigating PI/AGESA Version (Example from AMD-SB-7033 or reports)	Target Release by AMD (Example)
EPYC™ Server Processors
EPYC™ 7001 Series	Naples	SP3	NaplesPI-SP3_1.0.0.H	Dec’24
EPYC™ 7002 Series	Rome	SP3	RomePI-SP3_1.0.0.H	Dec’24
EPYC™ 7003 Series	Milan, Milan-X	SP3	MilanPI-SP3_1.0.0.F	Dec’24
EPYC™ 9004 Series	Genoa, Genoa-X, Bergamo, Siena	SP5	GenoaPI-SP5_1.0.0.E	Dec’24
EPYC™ 4004 Series	Raphael	AM5	ComboAM5PI 1.0.0.a	Jan 7, 2025
EPYC™ 9005 Series	Turin	SP7 (TBC)	TurinPI 1.0.0.44 / Ucode Turin: 0x0B002147	Mar 4, 2025
Ryzen™ Desktop Processors
Ryzen™ 3000 Series	Matisse	AM4	ComboAM4PI 1.0.0.D	Jan 14, 2025
Ryzen™ 5000 Series	Vermeer	AM4	ComboAM4v2PI 1.2.0.E	Jan 22, 2025
Ryzen™ 7000 Series	Raphael, Raphael X3D	AM5	ComboAM5PI 1.0.0.a / 1.2.0.3	Jan 7-8, 2025
Ryzen™ 9000 Series	Granite Ridge	AM5	ComboAM5PI 1.2.0.3c	(OEMs Apr’25)
Ryzen™ Desktop Processors with Radeon™ Graphics
Athlon™ 3000 Series / Ryzen™ 4000G Series	Picasso, Renoir	AM4	ComboAM4PI 1.0.0.D / ComboAM4v2PI 1.2.0.E	Jan 14-22, 2025
Ryzen™ 5000G Series	Cezanne	AM4	ComboAM4v2PI 1.2.0.E	Jan 22, 2025
Ryzen™ 8000G Series	Phoenix	AM5	ComboAM5PI 1.1.0.3c	Jan 27, 2025
Ryzen™ Mobile Processors (Illustrative)			(Refer to specific OEM for laptop BIOS updates)
Ryzen™ AI 300 Series	Strix Point, Strix Halo, Krackan	FP8/LGA	(Mitigation available)	(OEMs vary)
Ryzen™ Threadripper™ / PRO Processors
Threadripper™ 3000 Series	Castle Peak	sTRX4	CastlePeakPI-SP3r3 1.0.0.E	Dec 30, 2024
Threadripper™ PRO 7000 WX-Series	Storm Peak	sTR5/SP6	StormPeakPI-SP6 1.0.0.1k / 1.1.0.0i	Dec 16-19, 2024
AMD Instinct™ Accelerators
Instinct™ MI300A			MI300PI_SR5 1.0.0.8	Jan 14, 2025

Sources for Table A1: Primarily AMD Security Bulletin AMD-SB-7033, with supplemental info from tech media on Zen 5 AGESA versions and OEM release patterns. Release dates are AMD’s targets for giving PI to OEMs, or reported availability for end-user BIOS updates.

References

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• https://ioactive.com/exploring-amd-platform-secure-boot/
• https://www.binarly.io/blog/repeatable-supply-chain-security-failures-in-firmware-key-management
• (https://csrc.nist.gov/CSRC/media/Presentations/Draft-NIST-SP-800-193-Platform-Firmware-Resiliency/images-media/Day_2_AM_1_Draft_NIST_SP_800-193_Regenscheid.pdf)
• https://medcitynews.com/2025/04/the-future-of-healthcare-cybersecurity-preemptively-defending-against-emerging-threats/
• https://www.securitybrief.com.au/story/how-to-protect-legacy-medical-devices-from-modern-cyber-threats
• https://blog.exein.io/what-are-the-cybersecurity-risks-of-iot-devices-in-healthcare/
• https://www.mdpi.com/1999-5903/16/11/389
• https://www.dell.com/support/kbdoc/en-us/000275716/dsa-2025-052
• https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-01247.html
• https://www.theregister.com/2025/05/13/intel_spectre_race_condition/
• https://www.securitycompass.com/whitepapers/best-practices-to-ensure-firmware-security/
• https://www.intel.com/content/www/us/en/education/highered/it.html
• https://www.welivesecurity.com/2022/04/19/when-secure-isnt-secure-uefi-vulnerabilities-lenovo-consumer-laptops/
• https://www.halcyon.ai/blog/hitting-the-hardware-ransomware-moves-to-the-cpu
• https://indianexpress.com/article/technology/tech-news-technology/forget-software-researcher-develops-proof-of-concept-ransomware-that-infects-cpu-10000621/
• https://www.club386.com/amd-discloses-zen-5-cpu-microcode-vulnerability-and-will-release-a-fix-soon/
• https://www.amd.com/en/blogs/2025/addressing-microcode-signature-vulnerabilities.html
• https://access.redhat.com/security/cve/cve-2024-56161
• https://forum-en.msi.com/index.php?threads/latest-bios-agesa-pi-1-2-0-3c-release-notes-unclear.411806/
• https://www.picussecurity.com/resource/blog/t1082-system-information-discovery
• (https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1542.001/T1542.001.md)
• https://www.elastic.co/security-labs/the-grand-finale-on-linux-persistence
• https://developer.arm.com/documentation/110280/latest/
• https://support.hp.com/py-es/document/ish_12460666-12460692-16?validated=true&fallbackLocale=us-en
• https://news.ycombinator.com/item?id=42920921
• (https://patents.google.com/patent/US8515075B1)
• https://www.crowdstrike.com/en-us/cybersecurity-101/threat-intelligence/threat-hunting/
• https://coralogix.com/guides/mdr/10-threat-hunting-tools-to-know-in-2024/

We warned you it was deep.    You arent earning those CPE credits for nothing!

Continuing Professional Education (CPE) Credit

Earn CPE credits for reading this Security Blotter article. All Security Blotter articles that come with a Deep Dive section are eligible to earn free CPEs for you, the reader.  Our articles include all issues, incidents, and bulletins to relevant Infosec standards and best practices. We have documented your CPE submission below for your convenience and because we love you (in a platonic way).

Continuing Professional Education (CPE) Credit

Earn CPE credits for reading this Security Blotter article. This piece provides practical and technical insight into zero-day vulnerabilities, privilege escalation, and remote code execution threats targeting core Windows components. It is suitable for professionals maintaining credentials in cybersecurity, risk management, and incident response.

Article Overview

This article provides an in-depth analysis of Microsoft’s May 2025 Patch Tuesday, including the exploitation of five zero-day vulnerabilities, attacker tradecraft, detection strategies, sector-specific mitigation guidance, and prioritization tactics. The content aligns with core topics across security operations, incident response, governance, and software security domains.

• Word Count: 8,143

• URL: https://securityblotter.com/may-2025-patch-tuesday/

• Estimated Read Time: 41 minutes

• CPE Total: 0.75 CPE credits

• Publisher: Security Blotter

• Author: Jonathan Brennan – ISC2 Member ID 555001

🧾 CPE Submission Details

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📝 Additional Notes

• Other Certifications: This article may qualify for CPE credit with other certifications that recognize professional security education, including CompTIA Security+, GIAC, and vendor-specific programs.

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