The Mirai botnet was first spotted in august 2016 by the security researcher MalwareMustDie, it was specifically designed to compromise vulnerable or poorly protected IoT. Once Mirai malware compromises an IoT device it recruits it into a botnet primarily used for launching DDoS attacks, such as the one that hit Dyn DNS service.
In October 2016, the Mirai source code was leaked and threat actors in the wild started customizing their Mirai botnet.
The last variant of the Mirai botnet spotted in the wild by IBM researchers implements further capabilities, it includes a component for Bitcoin mining.
It is not surprising, crooks always try to catch every opportunity and the value of the crypto-currency has doubled in price in the last months reaching more than $1,290 per unit a few weeks ago.
“This new variant of ELF Linux/Mirai malware with the bitcoin mining component has us pondering, though.” reads the analysis published by IBM X-Force security researchers. “Attackers certainly have much to gain from having bitcoins in their pocket to facilitate their cybercriminal activities — bitcoin is the currency of choice for purchasing illegal commodities such as malware.”
The new Bitcoin mining-capable Mirai botnet was involved in a short-lived, high-volume campaign at the end of March.
The malware targeted Linux machines running BusyBox, most of them are DVR servers with default Telnet credentials.
The new Mirai variant targets this specific category of IoT devices because it uses their computing power to mine Bitcoin.
“The new ELF Linux/Mirai malware variant we discovered included another add-on: a bitcoin miner slave. This led us to question the effectiveness of a bitcoin miner running on a simple IoT device that lacks the power to create many bitcoins, if any at all. Given Mirai’s power to infect thousands of machines at a time, however, there is a possibility that the bitcoin miners could work together in tandem as one large miner consortium.” continues IBM. “We haven’t yet determined that capability, but we found it to be an interesting yet concerning possibility. It’s possible that while the Mirai bots are idle and awaiting further instructions, they could be leveraged to go into mining mode.”
The experts at IBM found the Mirai dropper in a web console and detected the site it was associated in a series of high-volume command injection attacks.
The website was used by operators as a malware package archive repository, experts discovered that the file package also included a Dofloo backdoor and a Linux shell.
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(Security Affairs – Mirai Botnet, Bitcoin)