New version of the Sober worm masquerades as Microsoft update

[InfoSec News <isn () c4i org>]

http://www.computerworld.com/securitytopics/security/story/0,10801,90899,00.html

By Paul Roberts
MARCH 08, 2004 
IDG NEWS SERVICE

Antivirus software companies warned customers about a new variant of
the Sober e-mail worm that began spreading on the Internet today and
masquerades as a Microsoft Corp. software update.

Sober.D is the latest version of a worm that first appeared in
October. The new worm poses as a software patch that will remove the
MyDoom virus from infected Windows systems, said antivirus company
F-Secure Corp. in Helsinki, Finland.

F-Secure first detected the new worm variant in Germany early today.  
The company rated the virus a "Level 2" threat, indicating "large
infections," the company said.

Like its predecessors, Sober.D spreads by skimming e-mail addresses
from victims' computers, then mailing copies of itself to those
addresses. Sober.D also adapts its message for German-speaking
audiences, inserting a German-language version of its pitch message
into e-mail addresses belonging to German domains, such as those
ending in .de, F-Secure said.

Copies of the Sober.D worm arrive in e-mail messages with the subject
"Microsoft Alert: Please Read!" or "Microsoft Alarm: Bitte Lesen!"  
said the antivirus company. The worm file is embedded in file
attachments with the .exe or .zip file extension and names such as
"Patch," "MS-Security" and "UpDate," F-Secure said.

Once the worm file has been opened, the virus places a copy of itself
on the infected machine's hard drive and modifies the Windows
configuration so that the worm file is launched each time Windows
starts, antivirus companies said.

When run, the worm mimics a legitimate software patch, displaying a
pop-up message indicating that the "patch has been successfully
installed." For machines that are already infected, the worm displays
a message saying that the "patch does not need to be installed on this
system," F-Secure said.

It is common for worm authors to dress up their creations as software
updates from Microsoft. Recent worms, including Swen and Gruel, have
posed as official correspondence from the software company.

In response, Microsoft declared that it never distributes software
updates using e-mail and has published guidelines for identifying
legitimate e-mail from the company.

Antivirus companies posted software updates to detect the new worm and
recommended that customers update their software as soon as possible
to prevent against Sober.D infection.

 

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