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F-Secure Virus Descriptions : MyDoom.L

[Summary] | [Detailed Description] | [Detection]

THIS VIRUS IS RANKED AS LEVEL 2 ALERT UNDER
F-SECURE RADAR.

Radar Alert LEVEL 2

NAME:MyDoom.L
ALIAS:I-Worm.Mydoom.L
SIZE:21008

Summary

A new variant of the MyDoom worm was found on July 19th, 2004 It is similar to previous variants. It spreads through email and copies itself to folders used by FTP and P2P software.

Detailed Description

The executable is packed with unmodified UPX.

When executed it will copy itself to:

 %windir%\lsass.exe

Where %windir% is the main Windows folder.

And create the following registry key.

 [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]

or

 [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]

 and sets the value:

 "Traybar" = %windir%\lsass.exe

Email Spreading

The emails sent by Mydoom.L will contain one of the following subjects:

 say helo to my litl friend
 click me baby, one more time
 hello
 error
 status
 test
 report
 delivery failed
 Message could not be delivered
 Mail System Error - Returned Mail
 Delivery reports about your e-mail
 Returned mail: see transcript for details
 Returned mail: Data format error

It may also compose the subject randomly.

Message bodies are chosen from:

 The original message was included as attachment

 This Message was undeliverable due to the following reason:
 Your message was not delivered because the destination computer was
 not reachable within the allowed queue period. The amount of time
 a message is queued before it is returned depends on local configura-
 tion parameters.
 Most likely there is a network problem that prevented delivery, but
 it is also possible that the computer is turned off, or does not
 have a mail system running right now.
 Your message was not delivered within [text filled by the worm] days:
 Host $i is not responding.
 The following recipients did not receive this message:
 <[text filled by the worm]>
 Please reply to postmaster@[text filled by the worm]
 if you feel this message to be in error.

 The original message was received at [text filled by the worm]
 from [text filled by the worm]
 ----- The following addresses had permanent fatal errors -----
 <[text filled by the worm]>
 ----- Transcript of session follows -----
   while talking to [text filled by the worm].:
 >>> MAIL From:[text filled by the worm]
 <<< 501 [text filled by the worm]... Refused

 The original message was received at $w
 from [text filled by the worm]
 ----- The following addresses had permanent fatal errors -----
 <[text filled by the worm]>

The attachment filename will be composed from combining the any of the following filenames:

 readme
 transcript
 mail
 letter
 file
 text
 attachment
 document
 message

and the following extensions:

 .scr
 .exe
 .com
 .pif
 .bat
 .cmd

It can also send ZIP files containing the worm. In that case the file inside the ZIP may have a filename resembling an email address or an extension followed by a large number of whitespaces finished with an executable extension.

Other spreading techniques

The worm will look for folder with the following text strings on them:

 incoming
 ftproot
 download
 shar

If any of them are found, it will copy itself inside those folders with names composed from:

 index
 Kazaa Lite
 Harry Potter
 ICQ 4 Lite
 WinRAR.v.3.2.and.key
 Winamp 5.0 (en) Crack
 Winamp 5.0 (en)

And followed by:

 .scr
 .com
 .exe
 .ShareReactor.com


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Detection

F-Secure Anti-Virus detects Mydoom.L worm since the following update:

[FSAV_Database_Version]

Version=2004-07-19_02

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Description: Ero Carrera, July 20th, 2004;

F-Secure Corporation