[ISN] Researchers uncover undetectable chip hack

From: InfoSec News (alerts@private)
Date: Thu Apr 17 2008 - 01:24:05 PDT


http://www.techworld.com/security/news/index.cfm?newsID=11993

By Robert McMillan
IDG News Service
16 April 2008

For years, hackers have focused on finding bugs in computer software 
that give them unauthorised access to computer systems, but now there's 
another way to break in: hack the microprocessor.

Researchers at the University of Illinois at Urbana-Champaign 
demonstrated how they altered a computer chip to grant attackers 
back-door access to a computer. It would take a lot of work to make this 
attack succeed in the real world, but it would be virtually 
undetectable.

To launch its attack, the team used a special programmable processor 
running the Linux operating system. The chip was programmed to inject 
malicious firmware into the chip's memory, which then allows an attacker 
to log into the machine as if he were a legitimate user. To re-program 
the chip, researchers needed to alter only a tiny fraction of the 
processor circuits. They changed 1,341 logic gates on a chip that has 
more than 1 million of these gates in total, said Samuel King, an 
assistant professor in the university's computer science department.

"This is like the ultimate back door," said King. "There were no 
software bugs exploited."

King demonstrated the attack on Tuesday at the Usenix Workshop on 
Large-Scale Exploits and Emergent Threats, a conference for security 
researchers held in San Francisco.

His team was able to add the back door by reprogramming a small number 
of the circuits on a LEON processor running the Linux operating system. 
These programmable chips are based on the same Sparc design that is used 
in Sun Microsystems' midrange and high-end servers. They are not widely 
used, but have been deployed in systems used by the International Space 
Station.

In order to hack into the system, King first sent it a specially crafted 
network packet that instructed the processor to launch the malicious 
firmware. Then, using a special login password, King was able to gain 
access to the Linux system. "From the software's perspective, the packet 
gets dropped... and yet I have full and complete access to this 
underlying system that I just compromised," King said.

The researchers are now working on tools that could help detect such a 
malicious processor, but there's a big problem facing criminals who 
would try to reproduce this type of attack in the real world. How do you 
get a malicious CPU onto someone's machine?

This would not be easy, King said, but there are a few possible 
scenarios. For example, a "mole" developer could add the code while 
working on the chip's design, or someone at a computer assembly plant 
could be paid off to install malicious chips instead of legitimate 
processors. Finally, an attacker could create a counterfeit version of a 
PC or a router that contained the malicious chip.

"This is not a script kiddie attack," he said. "It's going to require an 
entity with resources."

Though such a scenario may seem far-fetched, the US Department of 
Defense (DoD) is taking the issue seriously. In a February 2005 report, 
the DoD's Defense Science Board warned of the very attack that the 
University of Illinois researchers have developed, saying that a shift 
toward offshore integrated circuit manufacturing could present a 
security problem.

There are already several examples of products that have shipped with 
malicious software installed. In late 2006, for example, Apple shipped 
Video iPods that contained the RavMonE.exe virus.

"We're seeing examples of the overall supply chain being compromised," 
King said. "Whether or not people will modify the overall processor 
designs remains to be seen."


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