Cybercrooks have been distributing a Bitcoin mining malware with the aid of a cracked version of the Andromeda bot, Fortinet researchers reported on Wednesday.
Andromeda, one of the most well-known botnets, is currently at version 2.09. However, older versions can still prove to be useful, as researchers have discovered.
Cybercriminals have cracked an older version of the Andromeda bot, version 2.06, and they’re leveraging it to distribute a Bitcoin miner.
In the operation observed by Fortinet, the attackers don’t seem to possess the source code for the bot so they’ve cracked the original version and modified it to suit their needs, researchers said. The threat is detected as W32/Kryptik.AFJS!tr.
“The author removed the call to the RC4 subroutine, which the original version of the bot used to encrypt/decrypt certain portions of the bot’s code. The author might have done this in order to make it much easier to update the encrypted data, such as the URL of the C&C server and the corresponding RC4 key for encrypting the network traffic,” Fortinet researchers explained in a blog post.
Once it infects a system, the Andromeda bot contacts its command and control (C&C) server and downloads a Bitcoin miner binary detected as Riskware/BitCoinMiner. The malware is a new version of the threat, Fortinet told SecurityWeek.
“According to our brief analysis of this cracked version of Andromeda 2.06, we can see that a botnet’s life cycle can be longer than expected. Cybercriminals can buy botnet kits from the underground market, but can also use abnormal ways such as what we have described here – by cracking existing bots,” researchers noted.
Research by SecurityWeek shows that cracked versions of Andromeda are available on several hacker forums.
Mining Bitcoins requires serious resources these days, which is why some cybercriminals prefer to target organizations that store large amounts of the virtual currency. A perfect example is the recent Bitstamp breach in which 19,000 BTC (worth roughly $5.2 million) have been stolen.