Hi Jacob, I just watched your 30c3 presentation on Youtube. About halfway through you described an exploit on Dell servers that uses the JTAG, and then asked; "Why did Dell leave a JTAG debugging interface on these servers?”
There is nothing nefarious or uncommon about an active JTAG interface, especially on an expensive, warrantee-covered server product that may at some point in its useful life be sent back to Dell for repair. https://en.wikipedia.org/wiki/Joint_Test_Action_Group JTAG is a very common debugging and configuration port/interface that is used on all sorts of microchips and embedded systems. Sometimes there is an actual pinned header on the Printed Circuit Board but even if it is missing or covered, the JTAG circuitry can still be accessed on common pins or traces somewhere on the board. On a Dell motherboard there are probably dozens of JTAG and other debug pins… which could probably be used for various purposes, but it’s impossible to eliminate or turn off availability of this kind, they are inherent to the functionality of the device. Some manufacturers do obfuscate and encapsulate sensitive components of their machines (i.e., on military parts), but as with anything, physical access == ownership of hardware. (I am a hardware technician and have used JTAG and similar functionality to debug and repair electronic equipment in the field.) Thank you for your work, …quite eye opening. Pretty much, if something can be done, it has and will be done, by somebody out there. Isaac Gorton Spokane, WA ibgor...@gmail.com On Jan 5, 2014, at 9:31 AM, ianG <i...@iang.org> wrote: > On 31/12/13 23:13 PM, Jacob Appelbaum wrote: > >> I'm also happy to answer questions in discussion form about the content >> of the talk and so on. I believe we've now released quite a lot of >> useful information that is deeply in the public interest. _______________________________________________ cryptography mailing list cryptography@randombit.net http://lists.randombit.net/mailman/listinfo/cryptography
