Monday, July 07, 2008

the future of malware past

in the two most recent posts on eset's threatblog david harley has been talking about old malware... i don't just mean a couple months or even years old - seriously old malware from over a decade ago that none-the-less continues to cause problems for people...

in the first post david asked how this could be (and in the second pointed out that my answer was to more of a 'why' question than a 'how' one - just the kind of kick in the butt i need to remember to think twice and speak once)...

indeed, if you've got an on-access scanner you ought to be protected from old malware without even thinking about it, right? that simplistic view is certainly what most people have learned but if the infected disk isn't accessed until the computer is booting (a time when neither the on-access scanner nor the operating system itself are loaded yet) then that same simplistic view is proven to be a false sense of security...

that being said, the reason people don't think about or talk about or otherwise take special cases like this into consideration is the widespread (and false) belief that malware eventually becomes extinct... i've already stated numerous times that old viruses never die but what harm could that little mental shortcut really do? well, for one thing when left unchallenged it becomes a dominant pervasive belief... a belief so strong that certain best practices and safe hex behaviours like manually scanning disks before using them even though they're from your own backups or changing the boot priority in the BIOS to prevent possible boot sector infectors from getting an opportunity to execute fall out of common use and knowledge... a belief so strong that vendors may actually remove virus signatures from their signatures databases for performance reasons and eventually allowing viruses that have no good reason to still be around to once again cause problems for many people...

on the other hand, there's no way any reasonable person would accept a belief system that says old malware remains as much a threat now as it did when it was first released, so how should we think about this problem? i suggest that we think of old malware the way we think of landmines - long forgotten and unused but not entirely gone, and one false step and you may be hosed...

this goes for all malware, however one may rightly suggest that some malware won't age as well as others... malware that relies on some sort of infrastructure probably won't do so well in 10 years (when it's command and control network no longer exists or no one's listening to the domain it sends it's logs to)... older (pre-commercial) malware didn't tend to rely on such things though and viruses (due to their infectious nature) are more likely to find their way into backups and so be re-encountered weeks/months/years later... BSI's specifically may well prove to be the longest lived in practice because of their independence from and execution priority over the OS or most any other software component of the system... and of course since they're some of the oldest viruses (the first pc virus was a boot sector infector) and one of the first types to fall out of fashion, and since they're still causing problems, they're already off to a fine start...

foolishly forgetting or recklessly ignoring the the threat posed by old malware will ultimately make utilizing backups, archives, and just plain old media a bit like strolling through a minefield without a map... old malware won't go away, it will just lie dormant in the nooks and crannies of the computer world until we take that one wrong step and it comes back anew...

1 comments:

David Harley said...

It wasn't really meant to be a kick in the butt, Kurt. More the very gentlest of nudges to the ribs. :)

David Harley