The scariest type of all, hardware vulnerabilities. Security guru and creator of OpenBSD Theo de Raadt recently announced he had found some fairly serious bugs in the hardware architecture of Intel Core 2 Duo processors.

He goes as far as saying avoid buying a C2D processor until these problems are fixed.

A prominent software developer with a reputation for making waves in coding circles is doing it again – this time warning that Intel’s celebrated Core 2 Duo is vulnerable to security attacks that target known bugs in the processor.

Discussion forums on Slashdot and elsewhere were ablaze with comments responding to the claims made by Theo de Raadt, who is the founder of OpenBSD. Intel strongly discounted the report, saying engineers have thoroughly scanned the processor for vulnerabilities.

In it he warns that errata contained in the Intel processor is susceptible to security exploits that put users and enterprises at serious risk of being compromised. The exposure can exist even in cases where Intel has issued a fix, de Raadt said, because patches in the microcode frequently don’t get installed on systems purchased from smaller vendors or that run less popular operating systems.

“At this time, I cannot recommend purchase of any machines based on the Intel Core 2 until these issues are dealt with (which I suspect will take more than a year),” de Raadt concluded in his post to an OpenBSD discussion group.

The main problem being, these kind of issues cannot be fixed on a software level they need some re-engineering of the actual chips themselves and due to the nature of hardware vulnerabilities it means they can be exploited on any OS.

Many of the bugs lead to potentially dangerous buffer overflow in which write-protected or non-execute bits for a page table entry are ignored. Others involve floating point instruction non-coherencies or memory corruptions. Intel is aware of the security implications, but has yet to disclose them, he said in an interview.

Intel engineers and some outside security researchers disagree with de Raadt’s conclusion, but the implications of them being correct are serious. Thanks to its high performance and plentiful supply, the Core 2 Duo is seemingly everywhere – in Macs, phone switches and PCs running a wide variety of operating systems.

What’s more, a vulnerability in the processor could be exploited regardless of the OS it runs, and if the flaw resides in the silicon itself, the traditional remedy of pushing out a software patch could be rendered ineffective.

You can find 105 Core 2 errata here as published by Intel:

Core 2 Duo errata [PDF]

And the original e-mail from Theo here:

Intel Core 2

Source: The Register

One way to defend against OS fingerprinting from tools such as nmap, queso, p0f, xprobe etc is to change the metrics that they base their analysis on.

One way to do this with OpenBSD is to use Sealing Wafter.

Goals of Sealing Wafter:
1. To reduce OS detection based on well known fingerprints network stack behavior.
2. To have the ability to load custom rules into the stack.
3. To unload, modify, reload the kernel module with on the fly rules. (great feature at packet parties)
4. To learn how the magic of tcpip stacks work.

What Sealing Wafter currently provides:
1. Hide from Nmap Syn/Xmas/Null scans, as well as the specific fingerprinting packets.
2. Ability to see what your stack is receiving without the need to drop your network device into promisc mode.
3. Complete control over rules that you can load on the fly todeal with specific incoming packets.
4. Initial support for several OS passive detection has been added for SYNs.

Weaknesses in current Sealing Wafter:
1. Full connection scans. e.g. nmap -sT will still find open ports. this is because I have yet to find anything that seperates a real tcp connection vs an nmap full connection. (most likely isn’t one.)
2. Can be very verbose when under heavy load. I have run this on my heaviest web servers, and have not noticed any major overhead.

Download the c code for the LKM here: Sealing Wafter