Akamai researchers have investigated a crypto-mining botnet using its KmsdBot malware. The researchers accidentally caused the botnet to crash in a protected environment. Since the malware was programmed incorrectly, a command missing a space was enough to crash the botnet.
Earlier this month, Akamai Security Research published a blog post about KmsdBot, a cryptomining botnet that infects victims via SSH and weak credentials. After the malware infected an Akamai honeypot, the botnet was immediately analyzed and reported on in a post.
Botnet crash due to missing space
Akamai's experts continued to monitor the botnet and rendered it unusable by sending a few commands. The deadliest element of any malicious entity is the ability to gain command and control (C2). Since KmsdBot had C2 functionality, the experts wanted to test different related scenarios. Part of this testing consisted of modifying a recent example of KmsdBot to communicate with an IP address in the RFC 1918 address space.
This allowed the experts to play around in a controlled environment - and as a result, they were able to send their own commands to the bot on the test machine to test its functionality and attack signatures. Interestingly, after a single malformed command, the bot stopped sending commands. That prompts follow-up investigations. It's not every day you come across a botnet where the threat actors crash their own work. Interesting: A crashed bot no longer works. The system must first be reinfected in order to make it usable for the botnet again.
Poor programming of the malware
The experts found out as described in their blog post that a miscoded command line to the C2 crashed the network. The bot doesn't have any error checking built into its code to verify that the commands are formatted correctly. Therefore, a command with a missing space was enough to cause the crash. The complete technical description can be found in the blog post.
This botnet targets some very large luxury brands and gaming companies, and yet it cannot continue with one failed command.
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