By Robert McMillan
July 25, 2007
IDG News Service
The software that police and enterprise security teams use to
investigate wrongdoing on computers is not as secure as it should be,
according to researchers at iSec Partners Inc.
The San Francisco security company has spent the past six months looking
into two forensic investigation programs: Guidance Software Inc.'s
EnCase, and an open-source product called The Sleuth Kit. They have
discovered about a dozen bugs that could be used to crash the programs
or possibly even to install unauthorized software on an investigator's
machine, according to Alex Stamos, a researcher and founding partner at
Researchers have been hacking forensics tools for years but have
traditionally focused on techniques that intruders could use to cover
their tracks and thwart forensic investigations. The iSec team has taken
a different tack, however, creating hacking tools that can be used to
pound the software with data, looking for flaws.
Based on their findings, Stamos' team believes that the EnCase software
is not written as securely as it should be and could theoretically be
exploited by an attacker.
"What Guidance needs to do is change their production and their quality
assurance practices," Stamos said. "We looked at a small portion of the
functionality of EnCase, and we found that there are lots of bug that
can make it impossible for somebody to complete their work. Basically,
we can make it impossible to open up a hard drive and look at it."
ISec is holding the technical details of its findings close to its chest
and is not saying whether any bugs it found could be exploited to do
something much worse: install unauthorized software on a PC.
But the team will be disclosing some information at next week's Black
Hat conference in Las Vegas, Stamos said.
What, exactly, will be disclosed? The Sleuth Kit project has already
patched the flaws iSec has found, so those flaws will be made public.
Details on EnCase may be released if the product is patched by then,
Stamos said. ISec will also release the debugging and "fuzzing" tools it
used to find these flaws, he added.
The iSec research looks interesting but will probably not have a major
impact on the lives of forensic researchers, said Jim Butterworth,
Guidance's director of incident response.
Because forensic systems are typically not connected to external
networks, they can't be remotely controlled via the Internet, he said.
So even if an attacker could use these techniques to compromise one
forensic snapshot of a system, a second forensic tool would provide the
real picture. "It's just not that big of a threat, because I know a lot
of other mitigating steps to take," he said. "A well-trained person does
not use a single tool."
Another forensic researcher agreed that the iSec research is interesting
but of limited use to criminals.
That's because most serious attackers are already good enough at
covering their tracks that they will never be caught, according to James
C. Foster, president and chief scientist at Ciphent Inc. "If you're an
attacker, you can basically beat the system," he said. "In my opinion,
the bigger problem is that the product is not going to provide the data
that you want."
However, there is one group that may pay special attention to the Stamos
team: defense lawyers. If iSec shows that unauthorized software could
have been run on an investigator's PC, it could ultimately undermine the
usefulness of these forensic tools in court, said Chris Ridder,
residential fellow at the Stanford University Law School Center for
Internet and Society.
"The big risk is for someone to execute arbitrary code," he said "If
there's a risk that the evidence has been compromised or if something
has been planted by a third party... then you can call into question the
accuracy of the software and possibly get it thrown out."
Butterworth, who has been grilled many times by defense lawyers, agreed.
"I wouldn't put anything past a defense attorney ," he said.
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