Slapper has now infected at least 30,000 Linux Apache Web servers that haven't been patched to fix vulnerabilities related to the OpenSSL protocol detailed by The OpenSSL Group on July 30. Once infected by Slapper, the Linux Apache Web servers are forced to join a peer-to-peer network that can be used by anyone on the P2P network to drop any kind of application file directly into the infected servers.
Though Slapper is so far not suspected of carrying any dangerous payload, it opens the path for hackers to join the insidious P2P network to take advantage of compromised machines.
"We see .net, .mil and .com domains that have all been infected," commented Tony Magallanez, systems engineer at Finland-based security firm F-Secure. "Slapper sets up a Trojan on machines it infects and listens on the UDP port. You can drop files or applications right into the system."
Unlike most viruses, the Slapper P2P worm, which spreads by scanning for new victims, delivers its own source code and comes with instructions on how to use it, says Magallenez. F-Secure deployed a Linux Apache server as a sacrificial lamb to become infected so the security firm could observe the worm's spread and potential activity.
The main difficulty the Slapper worm has in spreading is that it has to compile itself, and "each and every binary will be a little different on each machine," said Magallenez. "All binaries on all Linux systems are a little different."
Linux Apache Web servers using the OpenSSL protocol - which should be patched according to the OpenSSL group's instructions - include Red Hat, Caldera, Stackware, and Debian.
Chances are that the worm is grabbing root privileges when it infiltrates a vulnerable Linux Apache Web server, Magallanez noted, adding that Slapper may have originated somewhere in eastern Europe, and the unknown author has included a disclaimer in good English that says the code is not intended for destructive use.
To remove Slapper from infected machines it will be necessary to look for three files in the directory, .uubugtraq; .uubugtraq.c; and .bugtraq, says Magallanez. The harder job will be doing a close inspection of any infected machine to determine whether important files have been changed or destroyed by anyone exploiting the P2P network created by Slapper.