Worms turn on Win/Linux users

Mighty, Opaserv

Amid the panic last week about the prolific, and very nasty, BearBug worm two more nasty varmints went largely unnoticed.

Hot on the heels of the Slapper, comes the Mighty worm which uses the same well-known OpenSSL exploit to gain access to and infect computers running an Apache Web server on Linux. Mighty uses the same spreading routines as Slapper but with several subtle differences.

In addition to infecting systems, Mighty also sets up a backdoor utility which can be controlled over an IRC channel. The Trojan component can be used to steal information from compromised machines, corrupt data or set up DdoS attack networks.

Russian AV specialists Kaspersky Labs says it registered over 1,600 systems infected by Mighty by last Friday.

Admins are strongly recommended to install the latest version of OpenSSL (for versions older than 0.9.7-beta, 0.9.6e) and to update their anti-virus tools to guard against infection.

Windows users, already hard hit by BugBear, face an additional threat from the Opaserv worm, whose main spreading mechanism (unusually) is via network shares.

The worm attempts to copy itself to the Windows folder on networked computers with open shared drives. It then modifies the win.ini file on the remote machine to ensure the copied file will be run on system start. The worm searches local IP addresses for open C: shares (using ports 137 and 139) and attempts to copy itself to the Windows folder of the share.

Opaserv also attempts to connect to a Web site that is currently unavailable, probably in an attempt by its author's to create a way to update the code used by the worm.

The worm illustrates the perils of running computers with open file shares. Users are advised to block this avenue of infection and to update their AV tools to detect the worm.

Updating AV protection is also a good idea in combating the spread of BugBear, which is spreading rapidly. Managed services firm MessageLabs has intercepted
more than 300,000 copies of the worm since its first appearance last week, eclipsing the perfidious Klez worm as the most common email-borne nasty. ®

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