Mandiant's "APT1" report early this year.
The group had been largely silent since the Mandiant report came out, according to FireEye, but is now actively conducting attacks again using retooled versions of Aumlib and Ixeshe, two previously known malware exploits that are used for targeted attacks.
Both of these malware families have been known for years, but the attackers appear to have rewritten them significantly, possibly in response to the APT1 report, FireEye says.
"We cannot say for sure whether the attackers were responding to the scrutiny they received in the wake of the [New York Times] episode," the blog states. "But we do know the change was sudden. Akin to turning a battleship, retooling TTPs [techniques, tactics and procedures] of large threat actors is formidable. Such a move requires recoding malware, updating infrastructure, and possibly retraining workers on new processes."
Some researchers said the retooled malware was predictable. "Since being exposed and subjected to wide-scale scrutiny and criticism of their operation from the security community, it should come as no surprise that these state-sponsored groups have upped their game," says Richard Henderson, security strategist for Fortinet's FortiGuard Labs.
"We often see variations in known malware in the field," says Jeremy Coons, senior manager of cybersecurity services at AccessData. "In fact, public release of reports such as the APT1 has actually increased that activity. It is a serious issue, as there is really no way to stay ahead of the curve."
Other security researchers confirmed that they are also detecting the revised malware, but were less inclined to connect it to the group that devised the attacks described in APT1.
"I don't think this code has anything to do with the APT1 report," says Adam Meyers, a researcher at security firm CrowdStrike. "I suspect after a number of years [the attackers] needed some upgraded functionality -- and, as FireEye states, because their traffic was readily identifiable, this lowered the effectiveness of their operations. But this actor is very different than the 'APT1' actor we call Comment Panda."
Some experts said the APT1 report may eventually make it more difficult to defend against sophisticated groups of attackers. "If you're playing poker and you discover your opponent has a 'tell,' you don't point it out to him," says John Prisco, CEO of security vendor Triumfant. "Malware authors are obviously going to be changing their tactics because the whole world already knows what tactics they were previously using -- thanks to the APT1 report that pointed out the tell."
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