New worm targets two Microsoft vulnerabilities

IDG News Service - Antivirus software companies are warning customers about a new e-mail worm that targets unpatched Microsoft Corp. Windows machines through either of two recently disclosed software vulnerabilities.
The new worm, known as both Plexus and Explet.A, was first detected on Wednesday and spreads by exploiting Windows machines with vulnerabilities used by two recent worms, Sasser and Blaster, according to alerts. Network Associates Inc.'s McAfee Antivirus Emergency Response Team and Symantec Corp. both said the new worm doesn't pose a serious threat, but the companies issued software updates yesterday to detect it.
Like Sasser, Plexus can exploit the recently disclosed hole in the Windows component called Local Security Authority Subsystem Service, or LSASS, which Microsoft patched in April. Like the Blaster worm that appeared last August, Plexus can also crawl through a hole in a Windows component called the DCOM (Distributed Component Object Model) interface, which handles messages sent using the remote procedure call protocol.
Plexus spreads in files attached to e-mail messages with faked sender addresses and vague subjects such as "RE: order," "For you" and "Good offer." When users open the virus file, the worm is launched and alters the configuration of Windows so that the worm program runs each time Windows starts. It also scans the hard drive of infected computers, harvesting e-mail addresses from a variety of files, including stored Web pages written in HTML.
The worm then uses those e-mail addresses to target other users, sending out a flood of messages using a built-in Simple Mail Transfer Protocol engine. It can also spread to other computers on a network using shared folders and copies itself to the shared folder file on the Kazaa peer-to-peer network using a variety of file names, including Shrek_2.exe, playing on the popularity of the recently released animated film.
Antivirus companies recommended that Windows users apply the software patches for the LSASS and DCOM vulnerabilities, and update their antivirus software to spot Plexus.

Reprinted with permission from

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