Nasty New Hybrid Strain of Ransomware
KnowBe4 CEO Stu Sjouwerman issued a warning of a scary new strain of ransomware, one with a difference, this one is a true self-replicating parasitic virus called VirRansom. This new strain is a hybrid that combines CryptoLocker and CryptoWall functionality with active self-replicating virus infections of all the files it can find. And, like the cybercrime Reveton family of malware, it locks the PC's main screen demanding 0.619 Bitcoin to let you back in.
Sjouwerman stated, “This ransomware threat utilizes both ransomware and parasitic virus features. VirRansom is a full-fledged virus which will spread across your network and doing a less than perfect job on the disinfection can easily lead to reinfection of your whole network. CryptoWall-encrypted files that you can't or don't decrypt are harmless garbage forever, but you can delete those. However, with VirRansom, files that you don't decrypt are still recoverable, but remain actively infectious.” Sjouwerman added; “What makes this tricky is the infected files can't just be deleted, since they are your own files that were there before the infection started.”
According to researchers at Sophos, most worms leave a handful of infected files that weren't there before and need to be deleted. Parasitic viruses, in contrast, may leave hundreds or thousands of infected files on each computer. If even one of those infected files is left behind, after a clean-up, the infection will start up all over again.
The file encryption is not as advanced as CryptoWall. For now, the key to decrypt the files is contained in the malware itself. Most antivirus should soon be able to decrypt the files and restore them, but the bad guys are constantly changing encryption keys in which case antivirus vendors may not be able to solve this fast enough..
Sjouwerman cautioned, “Ransomware gets nastier all the time. We can expect a VirRansom 2.0 with "new features" like industrial-strength CryptoWall-like encryption where files are held hostage until payment is made and email server infections where emails are converted to a worm for maximum dissemination of their malicious code. The legal ramifications could be horrific.”
Sjouwerman suggests IT managers mitigate these types of threats through both technical measures and enforcing security policy:
1. Test the Restore function of your backups and make sure it works and have a full set of backups offsite.
2. Start thinking about asynchronous real-time backups so you can restore files with a few mouse clicks.
3. Get rid of mapped drives and use UNC (universal naming convention) links for shared folders.
4. Look into Whitelisting software that only allows known-good executables to run.
5. Update or enforce security policy best practices, such as thorough effective security awareness training to prevent these types of infections to begin with, as the infection vector is your end-user opening up an attachment or clicking on a link.