Tuesday, May 01, 2007

Something Else To Look For...

Not long ago, Didier Stevens blogged about Windows Safe Mode and some Registry keys/values that pertain to Safe Mode. He filed this blog entry under "hacking". One of the cool things about computer forensics is that it's the flip side of hacking...discovering artifacts or "footprints" to find what kind of things happened on a system when it was "hacked".

Didier points out in his blog post how easy it is to write your own service that launches from Safe Mode. As more and more malware authors seem to be choosing a Windows service over the ubiquitous Run key in order to maintain the persistence of their malware on a system, it simply makes sense that a check should be made of the SafeBoot (Windows 2000, XP) key, as well.

Is this really such an issue, something you should be concerned about when performing IR or conducting an investigation? Let me add some perspective...not long ago, I examined a worm that had infected several systems, and it created an entry for itself in the RunOnce key; the entry was prepended with a "*". Does anyone get the significance of that?


Anonymous said...

Under the RunOnce keys, you can prefix a value name with an asterisk (*) to force the associated program to run even in Safe mode.

hogfly said...

This is pretty interesting. Safe mode is no longer safe and this should be examined before someone is told to "boot in to safe mode" to fix the problem (i.e, antivirus vendors).