Called Fbot, the botnet is a variant of one called Satori, which is in turn based on Mirai – a program normally used for DDoS attacks. Unusually, the DDoS module seems to have been deactivated and instead Fbot searches for devices infected with a specific crypto-jacking malware and replaces it in the system, the report says.
Discovered by the team at Qihoo 360Netlab, the variant seeks out a malware form dubbed com.ufo.miner – a variant of Android-based monero miner ADB.Miner.
Distributing itself by searching for devices with a specific open port, the botnet then uses a script to uninstall com.ufo.miner, if found. Fbot is programmed to scan and propagate, install itself over the malware and ultimately self-destruct, the researchers say.
Also unusually, the botnet code is linked to a domain name accessible, not through a standard domain name system (DNS), but a decentralized alternative called EmerDNS that makes addresses harder to trace and shut down.
The researchers said:
“The choice of Fbot using EmerDNS other than traditional DNS is pretty interesting, it raised the bar for security researcher to find and track the botnet (security systems will fail if they only look for traditional DNS names).”
It is not yet clear if Fbot has been set up by someone with good intentions or by a rival crypto-jacker seeking to remove the competition…