Home Security GhostHook: CyberArk finds new way to attack Windows 10

GhostHook: CyberArk finds new way to attack Windows 10

Researchers at CyberArk Labs have discovered a new way of gaining access to the innards of Windows 10 64-bit systems that can bypass existing safeguards, including the kernel patch protection known as PatchGuard that Microsoft developed to improve system security.

Yaacov Ben Naim (below., right), the company's senior director of Cyber Research, told iTWire that Microsoft had been told about the new attack method, which CyberArk calls GhostHook.

However, given that one already needs to have gained admin access to a system in order to use GhostHook, Ben Naim said Microsoft had said that nothing would be done now, and that the flaw that permitted the intrusion would be fixed in the next version of Windows.

When asked whether Microsoft's response was similar to the analogy of someone not wanting to catch an intruder who was planning to set fire to a house just because another person had already gained entry, Ben Naim agreed it was quite similar.

According to him, using GhostHook would allow an attacker to take over systems at the kernel level and remain undetected.

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kobi ben naimAsked whether it was possible that others had already discovered this method of intrusion and were sitting ensconced undetected within Windows 10 64-bit systems, Ben Naim said it was indeed a possibility.

The CyberArk statement said that 64-bit malware now comprised less than 1% of the total malware that afflicts Windows.

The GhostHook attack method could theoretically lead to the creation of sophisticated 64-bit malware which is often used as advanced persistent threats by national actors.

This is because the use of something like GhostHook along with 64-bit malware like Shamoon — disk-wiping malware that was used in an attack on Aramco, the Saudi Arabian state oil company — would give attackers more time undetected on a system for reconnaissance.

The CyberArk detailed blog post, published overnight, said the GhostHook attack was neither an elevation nor an exploitation technique. "This technique is intended for post-exploitation scenario where the attacker has control over the asset. Since malicious kernel code (rootkits) often seeks to establish persistence in unfriendly territory, stealth technology plays a fundamental role," the company said.

The technique that it had developed allowed attackers or information security products to hook almost any piece of code running on the machine.

Ben Naim said that once the details were released, security companies like McAfee, Symantec and others were likely to come up with ways of mitigating the effectiveness of GhostHook.

He said that proof-of-concept code would also be released when details of GhostHook were released.

When Microsoft was told about the attack, its response was: "The engineering team has finished their analysis of this report and determined that it requires the attacker already be running kernel code on the system. As such, this doesn’t meet the bar for servicing in a security update however it may be addressed in a future version of Windows. As such I’ve closed this case."

CyberArk expressed disappointment with this response. "Microsoft does not seem to realise that PatchGuard is a kernel component that should not be bypassed, since PatchGuard blocks rootkits from activities such as SSDT hooking, not from executing code in kernel-mode," it said.


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Sam Varghese

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A professional journalist with decades of experience, Sam for nine years used DOS and then Windows, which led him to start experimenting with GNU/Linux in 1998. Since then he has written widely about the use of both free and open source software, and the people behind the code. His personal blog is titled Irregular Expression.