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Today Slashdot published an article about a new exploit involving the Intel Management Engine (ME) which allows for undetectable exfiltration of data from a system via a Serial-over-LAN tunnel to an outside host. Because this does not involve the host OS it is not detectable there (via packet capture).

As I unterstand the article it is generally not possible to simply disable the ME.

This leads to my question: Which countermeasures can be taken to avoid that such Serial-Over-Lan tunnel can even be established to an outside host.

A comment in the original article on bleepingcomputer.com for example asks about ports that could be blocked in a router. Preliminary search did not reveal any usual ports and I wouldn't be surprised if there is no specific port involved, because it is software-defined by whatever RAT is running on the host.

Pondering this, I had the idea that because the AMT TCP/IP Stack is apparently not integrated into the OS stack, perhaps changing the OS MAC address and enforcing a router-based MAC access control could be effective? For me, the host OS would be windows 8. But I'd welcome answers for any host OS.

  • This is not an exploit. The malware is using legitimate remote management features that have been poorly locked down. – André Borie Jun 9 '17 at 17:05
  • @André Borie I am asking about possibilities to lock it down. You have any more insight to share here? – antipattern Jun 11 '17 at 23:28
  • Physically disabling, removing, or otherwise damaging any unnecessary physical interfaces on a machine not absolutely under your team's administrative control would be an obvious responsibility. Epoxy, stong adhesives, and glitter nail polish are all useful here. Not at all joking. – quadruplebucky Jun 12 '17 at 10:54
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AFAIK, stuff such as AMT(AMD has the same stuff call PSP), only works with a particular network adapter that supports the instruction.

So besides disable AMT from the BIOS, which is not 100% disable (unless you flash the firmware), another mitigation method is unplugged network cable connect to Intel adapter, and use another network adapter that doesn't talk Intel AMT.

There is a many Network adapter vendor. , since AMT is proprietary to Intel, so it is a safe bet that to use any external network adapter (not the internal one, as some may license technology from Intel to make it AMT ready) that not using Intel Chipset(with a risk of AMT enable).

  • Nice answer. Does that mean the cheapo china stuff actually has an advantage here? – antipattern Jun 11 '17 at 22:21
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    @antipattern In this sense, it'd seem so. It's worth noting that other hardware can have backdoors or/and vulnerabilities, too (example). There might be a Windows-has-more-viruses-than-Mac thing going on here, where larger vendors are more researched targets. – Nat Jun 12 '17 at 3:21
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Disable AMT and this should remove the problem. Follow this guide on how to do this.

Alternatively for the specific vulnerability there are a number of patches available.

Personally I would patch first at a minimum. If you do not require this feature I would also disable it, in addition to patching. This way if you ever enable it again for whatever reason it will be patched.

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There is a team that is actively developing solutions to disable the AMT chip at the source:

https://puri.sm/posts/deep-dive-into-intel-me-disablement/

It involves running a custom BIOS called coreboot: https://puri.sm/coreboot/

and removing critical parts of the AMT system: https://puri.sm/learn/intel-me/

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