Kaiten is Internet Relay Chat (IRC)-controlled malware typically used to carry out distributed denial-of-service (DDoS) attacks. The remastered malware has been dubbed “KTN-Remastered” or “KTN-RM”, with three versions identified by ESET researchers. Based on artefacts in the code, the main feature of the malware is an improved spreading mechanism.
Based primarily on Linux/Gafgyt’s telnet scanning, KTN-RM improves on that spreading mechanism by carrying downloader executable binaries for embedded platforms such as routers and other connected devices. Targeting is mainly aimed that devices with weak login credentials.
Linux/Remaiten improves upon the spreading mechanism by carrying downloader executables for CPU architectures that are commonly used in embedded ARM and MIPS Linux devices – the IoT (Internet of Things).
After logging on via the telnet prompt of the victim’s device, it tries to determine the new device platform and transfer only the appropriate downloader. This downloader’s job is to request the architecture-appropriate Linux/Remaiten bot binary from the bot’s C&C server. This binary is then executed on the new victim’s device, creating another bot for the malicious operators to use.
“The downloader’s job is to request the Linux/Remaiten bot binary from the Command & Control server for its current architecture. When executed, it also creates another bot for the malicious operators to use. We have seen this technique used before by Linux/Moose to spread infections,” says Michal Malík, ESET Malware Researcher.
In a strange twist, this strain of malware also has a message for those who might try to neutralize its threat.
"Within the welcome message, version 2.0 seems to single out malwaremustdie.org which has published extensive details about Gafgyt, Tsunami and other members of this family of Malware," adds Malik.
How to prevent and protect against this threat
- Change default passwords on network equipment even if it is not reachable from the Internet.
- Disable Telnet login and use SSH where possible
- Run the latest firmware available from your embedded device vendor
- Have an updated and appropriate anti-malware protection
- Be aware of the malware threat and what it does to devices
- If your device is infected, it might be used to infect others
- If infected, reboot the affected device then change its password as soon as possible. However, the attackers may have had manual access so further infection may have happened. In that case, a factory reset, firmware update or reinstall and password change is probably best