Cerber’s New Variant Evades Ransomware Decryption

August 9, 2016 @ 9:30 AM
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2 min read

Just as they did in earlier this summer, Cerber ransomware’s authors updated to a new variant by messing around with the ransomware decryption used in their criminal efforts.

Quirky From the Start

From its inception, Cerber has been a quirky and unique take on ransomware. It evades the most common antivirus checkers by updating its hash all the time. With a changed hash, the antivirus product lacks a signature to compare the malware against.

Because the malware is not explicitly on the blacklist, most antivirus products let it pass. Cerber is one of very few malware programs that has managed to pull off this kind of rapid hash change.

The malware authors have also shown they will change and revise things as needed. One such pivot was required after Trend Micro devised a free decryptor tool that cracked the first version of Cerber wide open. For a while, this threw a wrench into the criminals’ method of holding files hostage and getting money for the key.

Ransomware Decryption Is No Match

The malware authors went back to the lab yet again and emerged with new malware that has since been detected by security researchers. It shows evidence of massive alterations having been liberally applied to the program.

“Cerber v2 uses the CryptGenRandom Microsoft API to generate encryption keys, which are now 32 bytes long instead of 16 bytes,” reported Softpedia. Its new configuration also prevents the ransomware from running on PCs with certain types of security software.

Softpedia added that Cerber will not launch if it detects OS languages for the following countries: Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Kazakhstan, Moldova, Russia, Turkmenistan, Tajikistan, Ukraine and Uzbekistan.

One researcher involved in the Trend Micro effort noted that there was no solution available for the latest Cerber ransomware variants. Users can only hope that security firms are trying to replicate past success by creating a ransomware decryption tool for the more sophisticated version of this malware.

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Larry Loeb
Principal, PBC Enterprises

Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE mag...
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