New Worm Exploits Sasser Flaw
A new Internet worm is spreading by exploiting a flaw in the Sasser worm, according to an alert issued this week.
The new worm is tentatively named Dabber. It takes advantage of a vulnerability in an FTP server component in the Sasser worm and may have infected thousands of computers infected with Sasser. Dabber is believed to be the first worm that spreads specifically by targeting a flaw in another worm's code, according to an advisory published by LURHQ, a Chicago-managed security services company.
The worm uses code written to exploit the FTP flaw and was recently released on the Internet. It scans the Internet on port 5554 for computers running Microsoft's Windows operating system and infected with Sasser, LURHQ says.
When it finds vulnerable hosts, it connects to the victim and uses a built-in FTP server to transfer the worm file, named "package.exe," to the system. When run, the Dabber worm installs itself on Windows, shuts down the Sasser worm and other worm processes, then prevents them from running again. Dabber also opens TCP port 9898 as a backdoor, which can be used by a remote attacker to download other code or communicate with the infected host, LURHQ says.
Dabber does not appear to be spreading quickly, but the number of infections is escalating, LURHQ says.
