A Windows network worm which spreads through shared folders is spreading across Internet this week.
Unusually, the Lioten (or Iraqi Oil) worm doesn't spread via email, according to an analysis of the worm by AV specialists F-Secure.
Instead, Lioten scans the Internet on port 445 for Windows 2000 machines which have shared folders and weak or null passwords. Once a suitable vulnerable machine is found, the worm retrieves a list of user accounts (something blocked by default on Win XP but not Win2K) and tries to guess passwords. If the worm successfully logs onto a machine, it will copy itself over as an EXE file (usually named iraq_oil.exe) and executes it.
Then the process begins all over again.
Security clearing house CERT reports indications that attackers are monitoring for systems infected with Lioten and further exploiting them via other tools for use in distributed denial-of-service (DDoS) attacks. Lioten's scanning activity also poses a problem through wasted bandwidth.
The spread of the worm can be blocked by using ingress and egress filtering blocking connections to and from port 445/tcp on company firewalls.
Also the spread of Lioten once again emphasises the need to use strong (not easily guessed) passwords. To give a flavour of the general risk from trivially guessed passwords its worth listing those Lioten attempts to use:
If you are using any of these passwords (or any password which doesn't include a combination of letters and numbers) you're at risk - and not just from this Iraqi Oil worm. ®