Tuesday, August 03, 2010


... and by WAPT i mean wannabe APT.

so, one of the more colourful stories this past little while has been the stuxnet worm. apparently some people are having fun speculating about whether it's an example of a nation state targeting the critical infrastructure of another.

really i think we're just so uncertain about APT style threats that we're trying to find examples so as to make things more clear. does this case qualify? that's the question of the hour, isn't it. i guess i'll throw in my own 2 cents in the speculation game.

the components of this malware certainly lend themselves to a conclusion that it was part of an attack launched by an APT level of attacker. it's got a 0-day exploit to auto-execute itself when the directory containing the malware is viewed in explorer, a stealthkit to hide it's presence, digitally signed binaries using digital certificates from multiple well known companies to cause anti-malware software to overlook them, and a payload that targets a particular brand of SCADA (supervisory control and data acquisition) system.

do those properties really mean what they seem to mean though?
  1. we assume that the 0-day security flaw was developed by the attacker, which would seem to make the attacker technically advanced - but it is conceivable that the vulnerability was instead purchased, presumably for a very high price considering the calibre of the vulnerability, so this could instead be an example of the attacker being well funded and thus probably satisfying the persistent criteria for APT. 
  2. stealthkits aren't really that earth shattering these days, there are books and websites dedicated to teaching the reader how to make them so there's not much that can be inferred just from that. 
  3. getting access to a well known company's digital certificate in order sign one's binaries seems like a rather mysterious feat that could point to advanced skills, or insider access gained as part of the kind of detailed plan you'd expect from someone with persistence, except that it could also have been done with a turnkey crimeware kit like zeus. getting access to the digital certificates of two companies in the same geographic location makes the probabilities of advanced skills or persistence much less likely and simple opportunity much more likely.
  4. the SCADA-specific payload rather unambiguously points to a targeted attack (which is what a persistent threat would carry out), and also suggests access to similar SCADA systems for the purposes of R&D (which would probably tend to imply some financial backing), but it was put in a piece of self-replicating malware (malware that spreads itself in an automated fashion) which is pretty much the antithesis of targeted.
while a number of the components are suggestive of an APT sort of attacker, the way they were put together tells a different tale. even cybercriminals know that you don't use a distribution mechanism that essentially broadcasts (which is what you get when you use self-replicating malware) when you're performing a targeted attack. if you want your attack to go undetected then the last thing you want is for your attack to continue going on and on outside of your control. that lack of control is inherent in self-replication. it's what makes self-replicating malware (worms and viruses) unsuitable for targeted attacks. more than a decade ago, when the malware landscape was primarily worms and viruses, this principle was often arrived at whenever the discussion turned to the possibility of cyberwarfare - worms and viruses are a bad fit for attacking the enemy because they inherently cannot be controlled or aimed with any degree of precision and the possibility of infection spreading back to one's own systems is very real.

the people behind stuxnet certainly seem likely to have had financial backing, and the targeting conclusion seems unavoidable, but if they were advanced at all it was in a purely academic sense. they may have come up with the 0-day exploit and thereby qualified as researchers of some skill but they clearly don't have experience designing full attack campaigns from scratch. they don't understand the strategic strengths and weaknesses of the pieces they cobbled together and seem to have a somewhat antiquated idea of the malware threat landscape. if they were backed by a government, officially or otherwise, then that government must be in pretty dire straights to have employed the services of someone so green. it could, i suppose, have also been an attempt at industrial espionage, but either way the attackers' inexperience has tipped off the entire world to their efforts and that's pretty much an abject failure.