Botnet of Linux Servers with Dynamic IP Discovered

Linux being the server system of choice hasn't exactly escaped malware hackers. According to a current blog entry> from Russian developer Denis Sinegubko, a network of (meanwhile just under a hundred) infected Apache servers manage Windows systems through the dynamic DNS providers dyndns.org and no-ip.com and can thereby provide the malicious code.

The compromised Linux servers include dedicated or virtualized Apache webservers. The malware apparently landed on the target clients not because of an Apache vulnerability but due to weak or intercepted passwords or a security hole in the management software used. The attackers therefore installed next to Apache the small Nginx webserver that distributed the malware to the Windows clients. Site admins wouldn't normally notice the break-in because the Apache service wouldn't be affected.

The exact purpose of and, above all, the gateway used for the attacks are still not fully known. Shortly after Sinegubko's blog, the dyndns.com site took more than 100 systems off the net, and no-ip.com blocked about 100 domains after he contacted them. Unfortunately a cat-and-mouse game can ensue because dynamic hostnames can easily be registered.