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How can Intel AMT be used to bypass the Windows firewall?

Software developed by the hacking group Platinum takes advantage of Intel AMT to bypass the built-in Windows firewall. Expert Michael Cobb explains how it works.

Microsoft researchers discovered a hacking group file transfer tool leveraging Intel's Active Management Technology...

to bypass the built-in Windows firewall. How does Platinum's software abuse Intel's management tool?

The hacking group tagged as Platinum has further finessed its malicious file transfer tool, first discovered in 2016. It now leverages Intel's Active Management Technology (AMT) firmware to evade firewalls and other endpoint-based defense measures.

The AMT feature is present on Intel vPro processors and chips and is used for remote management. According to Microsoft and Intel, this is the first time an advanced persistent threat has been found abusing chipsets in this way.

Intel AMT runs in the Intel Management Engine (ME), which runs its own operating system on an embedded processor located in the chipset, making use of its own networking stack. As this embedded processor is separate from the primary Intel processor, it can execute even when the main processor is powered off, providing out-of-band remote administration capabilities, as it has access to the hardware network interface.

Intel AMT's serial-over-LAN (SOL) feature makes use of the ME's networking stack, enabling it to communicate even if networking is disabled on the host, just as long as the device is physically connected to the network. As SOL operates independently of the operating system and the host's networking stack, any communication over it is invisible to firewall, antimalware and network monitoring applications running on the host device. This makes it an ideal tool for hackers.

Platinum has upgraded its original file transfer tool, which used regular network APIs to exploit the SOL communication channel. However, to use it, Platinum first needs to gain administrative privileges on a system. This is because AMT is off by default, and it requires administrative privileges to establish an SOL session. This means that Platinum either obtained these specific credentials for a victim's networks or, after it obtained administrative privileges on a system, proceeded to provision Intel AMT and set its own credentials.

Microsoft's Windows Security blog provides detailed diagrams and videos of how the attack works. In the blog, Microsoft states that the Platinum tool doesn't expose flaws in Intel AMT, but uses it to evade security monitoring tools within an already compromised network.

As Platinum uses a legitimate management tool, one option is to not have Intel AMT enabled and to turn off serial-over-LAN communications. Even though Windows Defender Advanced Threat Protection can detect and notify network administrators of attempts to leverage the AMT SOL communication channel for unauthorized activity, robust security practices to manage access to privileged accounts are essential.

Platinum's modus operandi is to use spear phishing campaigns and Microsoft Office documents designed to take advantage of unpatched and known vulnerabilities to install backdoors and other code to establish a presence on a network. Their targets are mainly in Southeast Asia, and they include government agencies, defense contractors and intelligence agencies, as well as critical industries, such as telecommunications.

As always, up-to-date security awareness training is essential to combat phishing campaigns and to prevent attackers from gaining an initial foothold within a network.

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This was last published in November 2017

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