A sample of the Nemty ransomware family hid a strongly worded message directed at the antivirus industry within its code.
In its analysis of the threat, Bleeping Computer found that the ransomware deleted the shadow copies for the files it encrypted. This step effectively removed one way by which victims could recover their files for free. Upon completing its encryption routine, the crypto-malware then displayed a ransom note instructing victims to visit a payment portal hosted on the Tor network and submit 0.09981 BTC (worth $1,010.74 at the time of writing) in exchange for a decryption tool.
This particular ransomware stood out among other families, however, because it arrived with several messages hidden in its code. First, Bleeping Computer observed that the sample used “hate” as the name for its mutex object. Second, researchers noted how Nemty used a strongly worded message directed at the antivirus industry as the name for its key that decodes base64 strings and creates URLs.
A Look at Other Threats’ Hidden Messages
Nemty isn’t the only threat with hidden messages in its code. In December 2015, for instance, Emsisoft analyzed a variant of Radamant ransomware and found that the executables and domain names for the threat’s command-and-control (C&C) servers used strings that expressed displeasure toward the security firm.
Just a few months after in June 2016, the antivirus provider came across a sample of Apocalypse directing insults at its research team. That’s around the same time that Bleeping Computer reported on a sample of Black Shades Crypter ransomware that used hidden messages to taunt security researchers who might be analyzing it.
How to Defend Against Nemty Ransomware
Security professionals can bolster enterprise defenses against threats like Nemty ransomware by developing an incident response plan and practicing it ahead of real attacks. Organizations should also continue to focus on user education by investing in a security awareness training program that helps employees learn about phishing attacks, ransomware and other threats.
UPDATE: Researchers at Tesorion took a close look at Nemty and noticed a few crucial deviations in the threat’s implementation of the AES-CBC encryption algorithm. Using those deviations, the researchers developed a process that allows victims in some cases to recover their affected files for free.
David Bisson is an infosec news junkie and security journalist. He works as Contributing Editor for Graham Cluley Security News and Associate Editor for Trip...