[ISN] New Bagle, MyDoom variants roil Internet

From: InfoSec News (isn@private)
Date: Wed Jul 21 2004 - 06:49:22 PDT


By Paul Roberts
IDG News Service

New versions of the Bagle and MyDoom worms surfaced on the Internet 
Monday, and appear to be spreading.

Bagle.AI and MyDoom.N are both so-called "mass mailing" worms that use 
a built-in SMTP engine that sends e-mail messages carrying 
worm-infected file attachments from computer to computer on the 
Internet, both using faked (or "spoofed") sender addresses, anti-virus 
companies said. 

The new worm variants are just the latest in a string of virus 
releases in recent days that have anti-virus software companies 
scrambling to keep their customers protected. 

W32.Bagle.AI first appeared Monday and is rated a "medium" threat by 
McAfee's Antivirus Research Team, citing reports of the virus from 
customers. McAfee rated MyDoom.N a "low" threat, whereas Computer 
Associates noted the prevalence and destructiveness of the worm. 

Similar to earlier versions of Bagle, the AI variant spreads through 
shared file folders and in e-mail messages carrying the worm file as 
an attachment, according to advisories from Sophos PLC and McAfee. 

E-mail messages generated by the worm used forged (or "spoofed") 
sender addresses and the subject line "Re:" Worm-infected file 
attachments might be in ZIP, EXE, SCR, COM or CPL and also have 
nonspecific names like "Moreinfo," "Details" or "Readme," anti-virus 
companies said. 

Infected file attachments use one of a short list of names including 
"MP3," "Doll" and "Cat."

The worm can also send copies of itself as a password-protected 
compressed file with a ZIP extension. The password needed to unzip the 
ZIP file is contained in a second file with a TXT, INI, DOC or other 
extensions, McAfee said. 

The MyDoom.N worm uses spoofed sender addresses such as "postmaster," 
"Post Office" and "MAILER-DAEMON" that make the e-mail resemble a 
rejected message. 

MyDoom.N messages also have nondescript Subject lines such as "hello," 
"hi" and "delivery failed." Virus file attachments have names like 
"readme," "mail," "text" and "attachment." File extensions include 
CMD, BAT, COM, EXE and ZIP, McAfee said. 

Anti-virus companies issued updated virus definitions that can detect 
the new Bagle and MyDoom variants and recommended that customers 
update their anti-virus software. 

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