Windows 11 (24H2): Breaking Process Hollowing and Malware Defense

If you're a Windows 11 (24H2) user or someone who keeps a keen eye on cybersecurity threats, listen up—because this one's a game-changer. Researchers have recently uncovered new vulnerabilities tied to a well-known malware technique called Process Hollowing, and they could either enhance your system's security posture or complicate your cybersecurity toolkit. Let's dive deep into what's happening under the hood of Windows 11 (24H2) and what it means for the future of malware defense.

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Breaking Process Hollowing: Windows 11 (24H2)'s Bold Move​

Process Hollowing, sometimes referred to by its alias, RunPE, has been a long-standing favorite tool in the hacker's arsenal. For the uninitiated, this technique involves a malicious program impersonating a legitimate process. Imagine a wolf in sheep's clothing—except this wolf is packed with malware, and the sheep it's impersonating could be any program Windows trusts.
Here’s the kicker: Windows 11 (24H2), released on October 1, 2024, has introduced changes that disrupt this party trick. Enter the hero—or villain, depending on your perspective—the Windows loader, which no longer plays nicely with many of the traditional Process Hollowing tricks.
Instead of quietly letting hackers embed a malicious PE (Portable Executable) file in memory and masquerade it as a friendly, non-threatening app, Windows 11 (24H2)’s loader throws an error: 0xC0000141. Game over—at least, for a lot of known malware.
Now, what’s behind this change? Two key transformations are at play:

• Integration of RtlpInsertOrRemoveScpCfgFunctionTable in Windows Loader
  The introduction of this function has enabled hotpatching to interact with the ZwQueryVirtualMemory function, which aggressively inspects memory regions.
• RunPE and MEM_PRIVATE vs. MEM_IMAGE
  Simply put, RunPE implants land in memory regions tagged as MEM_PRIVATE, unlike legitimate processes stored as MEM_IMAGE. This discrepancy now triggers the STATUS_INVALID_ADDRESS error during memory checking by ZwQueryVirtualMemory.

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The Fallout: A Battle of Innovation​

While these changes shore up Windows defenses against malware, they’ve also posed challenges for both attackers and legitimate security researchers. Here's the million-dollar question: how do you fight back when your tried-and-true techniques don't work anymore?

Potential Solutions (Adapt or Die)​

• Alternative Malware Evocation Techniques
  Researchers and threat actors alike are pivoting to novel techniques to counteract these security changes. Some viable options include:
• Process Doppelgänging: Uses NTFS transactions to create a fake process.
• Process Ghosting: Creates a legitimate-looking process but replaces the code in memory.
• Transacted Hollowing: Incorporates transaction features to bypass loader checks.
• Ghostly Hollowing: A hybrid method, closer to Phantom Hollowing, to mimic legitimate processes.
• Process Overwriting: Overwrites existing processes while keeping the core process structure intact.

These techniques focus on creating processes that either reinterpret or bypass the memory tag issue entirely, making them appear more "legitimate" to the loader.

• Patching NTDLL (Hack Alert!)
  A more aggressive approach is patching the ZwQueryVirtualMemory function inside NTDLL.dll. By modifying how memory queries operate, researchers (and hackers) avoid the memory mismatch errors. However, messing with NTDLL.dll is risky business—it could easily lead to system instability or panic errors.

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Why This Matters: Malware Evolution vs. Cyber Defense​

The changes in Windows 11 (24H2) are part of Microsoft’s ongoing tug-of-war between securing systems and staying a step ahead of increasingly sophisticated threats. However, downsides exist—a better-protected system inadvertently forces security researchers into more complex methodologies to test defenses and validate vulnerabilities.

Implications for Cybersecurity Teams​

• Enhanced Security Posture: The updates disrupt legacy Process Hollowing vectors, making Windows 11 (24H2) inherently harder to penetrate with older malware techniques.
• Increased Complexity for Testing: Security tools must now evolve to deal with these changes. Researchers can no longer reliably use process-hollowing-based implants for red teaming or penetration tests without adopting the aforementioned alternatives.
• Risk of Collateral Damage: While these changes neutralize certain threats, adding complexity to essential system processes could lead to unforeseen bugs or issues for end-users.

What Can You Do as a User?​

It's always a balancing act between staying secure and functional, but here are a few tips:

• Keep Systems Updated: Always install the latest Windows updates to benefit from built-in defenses like this.
• Use Reliable Security Tools: Leverage modern endpoint detection and response (EDR) tools that can catch malicious activity beyond traditional techniques.
• Collaborate with Your IT Team: Organizations should validate their current defense tools to ensure that new malware evasion techniques like Process Ghosting aren't sneaking by unnoticed.

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Our Final Take​

Windows 11's (24H2) change feels like watching Hollywood’s action-reboot of an old classic. Familiar tropes still linger, but new twists rewrite the rules. Process Hollowing won't disappear overnight—it’s a technique that's evolved and adapted over decades. However, these changes highlight the undeniable fact that Windows defenses are raising the bar.
So this begs the question—how will hackers, security professionals, and the broader industry rise to meet these challenges? Perhaps Process Doppelgänging will take the lead, or perhaps entirely new vectors will emerge. Either way, it’s an exciting—if challenging—time to be in cybersecurity.
What’s your take on this evolving malware arms race? Feel free to share your insights or questions below!

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Source: GBHackers News New Process Hollowing Attack Vectors Uncovered in Windows 11 (24H2)