A new network worm that spreads through shared folders on machines running Windows NT, 2000 and XP operating system has been detected, according to advisories posted by a number of antivirus software makers.
The new worm, called W32/Lioten, also goes by the name Iraq_oil, Datrix, W32.Lioten and I-Worm.Lioten, according to an advisory posted by Finnish security company F-Secure.
Unlike other worms that spread through mass e-mailing, Lioten scans the Internet for vulnerable Windows machines that are sharing folders with other users on a home or business network.
The worm finds new hosts to infect by randomly generating and attempting to connect to IP (Internet Protocol) addresses on the Internet. The worm listens for responses on port 445 from machines using Windows Server Message Block (SMB), a file and resource sharing protocol used in Windows environments.
Once the new worm receives a response from a server, it attempts to crack that machine using a so-called "brute force" attack. The worm first obtains a list of user accounts on the machine and then attempts to log in to each of those accounts by supplying values from its own list of likely passwords such as "admin," "root," "1234" and "asdf".
If the worm is successful in logging on to a machine using any of the user accounts, it places a copy of itself, iraq_oil.exe, in the System32 directory on that machine and creates a process on the machine to run the new executable.
It is not known what else the worm does besides propagate itself, nor is the relevance of the "Iraq oil" reference understood, F-Secure said.
Machines that are located behind a firewall are likely to be protected from the new worm. Even basic firewall configurations will block access to port 445, according to F-Secure.
Leading antivirus software makers including Symantec, Network Associates, makers of McAfee, F-Secure and Sophos gave Lioten a "low" threat rating, indicating that the worm has not spread widely on the Internet and few if any infections linked to the Lioten worm have been reported.
Still, antivirus companies posted updated virus definitions yesterday that are capable of detecting the Lioten worm and recommended that customers running the affected operating systems download the latest virus definitions for their antivirus software.