Sunday, May 31, 2009

Packers and protectors - evading AV

"It is ironic but the extreme growth rate of malware attacks is actually partly due to how successful AV technology really is. Quite simply - if AV scanners were not so successful in blocking trojans and viruses there would be little need for the bad guys to write new ones. One can even say that malware writers are digging an elephant trap for all computer users because lots of new malware demands a response from AV, which can contribute to the slower operation of computers for all of us.

Figuratively speaking, the primary tools that the bad guys are using to dig their side of the trap and evade detection are packers (like UPX and Petite) and protectors (like Armadillo and Themida). Packers are legitimately used to reduce the size of programs (saving disk space), while protectors are legitimately used to prevent patching, hacking or reverse engineering. For malware production, however, packers and protectors are useful as they can often obfuscate original malware beyond recognition by AV.

Commercial protectors are especially loved by malware writers because they can put a protective envelope on top of, say, their spam-bot and it will be well hidden inside. Additionally, it will now really look more like a legitimate file obfuscated with the same protector. Malware writers use this trick more and more frequently."

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