Adware Campaign Using Advanced Nation-State Obfuscation Techniques

Adware makers are becoming more malicious and upping their obfuscation game, according to new research out from Carbon Black's incident response and research team. In a report out late last week, they say that variants of well-known adware are now using evasion techniques first developed for nation-state attacks, including Operation Aurora.

As the lead of the Advanced Consulting Team for Carbon Black, Benjamin Tedesco wrote about his experience running into the behavior early last week during an incident call with a customer. The first clue that the customer was experiencing Aurora-like behavior was when he and the customer discovered unusual use of command line argument activity that was a hallmark of that specific attack, namely "cmdline:cop AND cmdline:/b".  That set them digging further and finding details that pointed to a highly advanced attack scenario.

"So, now for the 'stranger' part. As we began to walk backward up the process tree, we began noticing that the parent processes launching these rather advanced obfuscation techniques were 'routine' adware, flagged multiple times by Virus Total. I was stunned," he wrote, noting variants included OpenCandy, Dealply and trojanized Chromium.

Just that day alone his next two calls dealt with similar infection behavior, and after posting details on the Carbon Black customer community site, "reports began to pour in regarding similar findings across our customer base." Those affected spanned across industries and organizational sizes. As his team continued research, they found the possible reason for such sneaky behavior. 

These variants of adware are potentially being used as a delivery vector for the Enigma ransomware variant.

"All of a sudden, the level of advanced obfuscation for this “Adware” makes sense. This Adware appears be the stager being used to covertly distribute the binaries (believed to be) attributed to ransomware and other classes of malware," Tedesco says.

According to Tedesco, the techniques used by these variants easily evade sandboxing and other intrusion detection techniques by using binary fragmentation. Once they've gained a foothold, they're able to bypass security controls, install more payloads and eventually completely compromise the machine. One of the biggest lessons to take away from this new campaign is that adware and other potentially unwanted programs (PUPs) aren't always an insignificant threat. 

"These seemingly innocuous applications are growing progressively more malicious in their impact to an environment," he warns.

The research on this campaign and infection vector is developing, but in the meantime if an organization doesn't have the ability to inspect command line arguments, his team suggests that they check out Scheduled Tasks for suspicious newly created tasks because the variants are using Windows Task Scheduler to establish persistence.