Steve Davis and I gave a talk at Blackhat and at Defcon called
Autopsy: Reconstructing the scene of the crime. Giving
the talk was a blast; both Steve and I were thrilled to be given an
opportunity to give a defensive security talk on the Metasploit
track. During our talk and in several interviews, we stated that
some aspects of computer security are a cat and mouse game. When you
make a technique, tool, or other knowledge public people have a
chance to analyze what you have done. This analysis can lead to
better code, improvements to ideas, or in some cases the breaking of
said tools. In the case of
Forensic Framework (MSFF), the newest release of Metasploit
flat out broke MSFF. First, let me give you some background. When we
first started writing the tool, we quickly realized that breaking
MSFF would take a single line change to Meterpreter. The fix is
simple. In our talk, we discussed that when meterpreter called
free the received/sent packets were not scrubbed and lay
around memory for hours. MSFF capitalized on this using
to acquire the processes address space which included the
process's freed memory. HD and crew were nice enough to wait to
patch Meterpreter until after our talk. Meterpreter was patched
Saturday with memset's, which zero out the packet data before
the memory is freed.
With this fix, our current technique to
reconstruct what Meterpreter sent or received does not work. The
Metasploit project has broken that ability successfully (something
we expected). Our detection will evolve, and HD discussed some ideas
he had to make detecting the Meterpreter binary harder. Currently,
MSFF can still be used to identify the injected binaries in a
process's address space. The Meterpreter binary contains too much
code and has too many features to effectively hide in memory. If and
when HD patches the reflective loader to scrub Meterpreter's binary
data, we'll update MSFF with some fix, more as a proof concept than
anything else, to continue to identify the injected DLLs. Hope
everyone's recovered from Vegas!
A huge thanks go to Ping,
Nikita, Jeff Moss, Val Smith and HD for putting the Metasploit track
together. It was not easy, but it went great. A huge thanks to the
defcon speakers, who were very flexible.