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There's often a lot of discussion about whether a piece of malware is advanced or not. To a large extent these discussions can be categorized as academic nitpicking because, at the end of the day, the malware's sophistication only needs to be at the level for which it is required to perform — no more, no less. Perhaps the "advanced" malware label should more precisely be reattributed as "feature rich" instead.

Regardless of whether a piece of malware is designated advanced or run-of-the-mill, and despite all those layers of defense that users have been instructed to employ and keep up to date, even that ever-so-boring piece of yesteryear malware still manages to steal its victims banking information.

How is that possible?

I could get all technical and discuss factors such as polymorphism and armoring techniques, but the real answer as to why the malware manages to slip by all those defenses is because the bad guys behind the attack tested it prior to release and verified that it was already "undetectable" before it was shipped down to the victim's computer. Those host-based defenses had no chance.

It's worthwhile noting that generating "unique" malware is trivial. Armed with a stock-standard off-the-shelf DIY construction kit, it is possible to manually generate several hundred unique variants per hour. If the cyber-crook is halfway proficient with scripting they can generate a few thousand variants per hour. Now, if they were serious and stripped back the DIY kit and used something more than a $200 notebook, they could generate millions of unique variants per day. It sort of makes all those threat reports by anti-virus vendors that count the number of new malware detected each month or year rather moot. Any cyber-criminal willing to do so could effectively choose what the global number of new malware will be and simply make enough variants to reach that target. I wonder if any online betting agencies will offer worthwhile odds on a particular number being achieved. It may be worth the effort.

Armed with a bag of freshly minted malware, the cybercriminal then proceeds to test each sample against the protection products they're likely to encounter on potential victim's computers — throwing out any samples that get flagged as malware by the anti-virus products.

Using a popular malware DIY construction kit like Zeus (retailing for $4,000, or free pirated version via Torrent download networks), the probability of any sample being detected even at this early testing stage tends to be less than 10 percent. If the cybercriminal chooses to also employ a malware armoring tool that average detection rate will likely drop to 2 percent or less.

Obviously this kind of testing or, more precisely, Quality Assurance (QA) is a potentially costly and time-consuming exercise. Never fear though, there are a lot of entrepreneurs only too happy to support the cybercriminal ecosystem and offer this kind of testing as a commercial service.

Today there are literally dozens of online portals designed to automatically test new malware samples against the 40+ different commercially-available desktop anti-virus and protection suites — providing detailed reports of their detection status. For as little as $20 per month cybercriminals can upload batches of up to 10,000 new malware samples for automated testing, with the expectation that they'll receive a thoroughly vetted batch of malware in return. These "undetectable" malware samples are guaranteed to evade those commercial protection products. As a premium subscription service model, for $50 per month, many QA providers will automatically fix any of the malware samples that were (unfortunately) detected and similarly guarantee their undetectability.

Armed with a batch of a few thousand fully-guaranteed malware samples that are destined to be deployed against their victims in a one-of-a-kind personalized manner, it should be of little surprise to anyone precisely why run-of-the-mill or feature-rich malware manages to infect and defraud their victims so easily.

By Gunter Ollmann, VP of Research at Damballa. Visit the blog maintained by Gunter Ollmann here.

Related topics: Cybercrime, Malware, Security