Ransomware Recap [Sept. 2, 2016]: CryLocker Uses Imgur as C&C

Last week, Trend Micro researchers have started paying close attention to a particular ransomware strain that is reportedly dropped via the Rig exploit kit. Not long after, Sundown exploit kit was also seen distributing a ransomware variant, called CryLocker (detected as Ransom_MILICRY.A), with similar behavior and evasion tactic, which interestingly involves the use of a legitimate image upload service.

Following encryption of targeted files, the ransomware in question collects information from the victim’s machines and packages them into a malformed .png file before it uploads it in an album found in Imgur, a legitimate site, which in turn serves as its C&C server. Apart from appending a .cry extension to its encrypted files, which is similar to a Buddy ransomware, there appears to be no previously-detected family affiliated or connected to this particular ransomware strain. However, analysis and observations on its behavior and its reach are still ongoing.

Interestingly, a ransomware strain called FairWare emerged at the beginning of the week, reportedly targeting Linux users by hacking a Linux server—demanding a ransom of 2 bitcoins on a 2-week deadline. Not long after, researchers at Duo Security reported malicious activity on Redis server that resulted into the installation of a fake ransomware. This then led to the discovery that FairWare was in fact a scam disguised as a ransomware infection. Cybercriminals behind the ruse tricks would-be victims that the “hostaged” files are simply locked and in need of a decrypt key, which can be obtained by paying a ransom amount. In truth, there were no indications that the files are archived before it was deleted from the victim’s system.

In the past, an actual ransomware family, Ranscam, did the same—promising to provide a decrypt key following payment of demanded ransom, when in fact, the files had already been deleted. This time, the perpetrators behind FairWare relied heavily on using the idea of losing access to one’s important files as a scare tactic to rake in profit.

[Related: The psychology behind ransomware’s success]

Here are other notable stories that surfaced over the past week:

The continuing surfacing of new families and updated variants, and even the emergence of scams that feign an infection show that ransomware is not going anywhere anytime soon. However, this should serve as a reminder to end-users and organizations to bolster defensive strategies that would keep ransomware infections at bay and more importantly, to stop the cycle of compromise by not paying the ransom when infected.

Instead, a multi-layered approach that secures all possible gateways from this threat is the best way to defend against ransomware. A solid back-up of valuable files, on the other hand, mitigate damages brought by a ransomware infection.

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