New Internet worm targets e-mail, P2P software

[InfoSec News <isn () c4i org>]

http://www.nwfusion.com/news/2003/0918newinter.html

By Paul Roberts
IDG News Service
09/18/03

Anti-virus companies are warning Internet users about W32.Swen, a new
worm that spreads using e-mail messages, vulnerable network
connections, IRC (Internet Relay Chat) and peer-to-peer networks.

First detected on Thursday, Swen exploits a security hole in
Microsoft's Internet Explorer Web browser and affects all supported
versions of the Windows operating system, according to F-Secure of
Helsinki.

The worm poses as a software security update from Microsoft prompting
users with "Yes" or "No" buttons to agree to install the update and
even an installation "progress" bar if they do agree.

However, the worm code is installed regardless of what users select.  
Once on an infected system, Swen alters the configuration of the
Windows operating system so that the worm is launched whenever Windows
is started. The worm also detects and disables anti-virus software or
other Windows features that could be used to disable it, according to
F-Secure.

Like other mass mailing worms, Swen scans an infected machine's hard
drive for e-mail addresses and uses those to send out more copies of
itself, skimming SMTP server addresses and user names from Windows.

Infected e-mail messages are formatted to look like official
correspondence from Microsoft. The messages appear to come from one of
a variety of randomly generated senders like "MS Technical
Assistance," and advertise a "cumulative patch" for Internet Explorer
to patch "three newly discovered vulnerabilities," F-Secure said.

The worm also can detect the presence of IRC clients or the Kazaa P2P
file-sharing software and distribute itself on those networks. Swen
places a specialized script file that sends a virus file to every
computer on the same IRC channel as the infected computer.

For machines running Kazaa file-sharing software, Swen enables the
file-sharing feature, if it is not already enabled, and places
multiple copies of itself in the Kazaa shared files folder disguised
as Kazaa client software, pirated software or other popular
applications, F-Secure said.

F-Secure, Network Associates and Symantec all issued warnings about
Swen Thursday, indicating that the worm is spreading on the Internet.

More than one antivirus company noted the similarity between Swen and
an earlier worm, W32.Gibe, which appeared in February. Like Swen, Gibe
also attempted to spread via e-mail, as well as Kazaa and IRC networks
while posing as a piece of legitimate Microsoft software when
installed.

Customers are being advised to update their anti-virus definitions to
detect Swen.



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