Sophos

W32/MyDoom-AJ

Category
Type
What to do
Prevalence low high

Summary

 
How it spreads
  • Email attachments
Affected operating systems Windows
Characteristics
  • Installs itself in the registry
Included in our products from June 2005 (3.94)
Protection available since 9 April 2005 15:39:12 (GMT)
Detected by All Sophos products

Action

Please follow the instructions for removing worms.

If you are running Sophos Anti-Virus for Windows, version 6.0, you should follow our instructions for removing worms.

If you use any of our other products for Windows NT/2000/XP/2003 and Windows 95/98/Me please read the instructions for removing W32/MyDoom-AJ.

More Information

W32/MyDoom-AJ is a mass-mailing worm with IRC backdoor functionality which can also infect computers vulnerable to the LSASS (MS04-011) exploit.

Emails sent by W32/MyDoom-AJ have the following characteristics:

Subject line chosen from one of the following, possibly in all uppper case or all in lower case:

Good day
Hello
Server Report
Status
<blank>

Message text chosen from:

Mail transaction failed. Partial message is available.
The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.
The message contains Unicode characters and has been sent as a binary attachment.
The original message was included as an attachment.
<junk>

Attached filename chosen from the following with an extension chosen from (bat cmd exe scr pif zip):

body
data
doc
document
file
message
readme
text

Sophos's anti-virus products include Genotype ™ detection technology, which can proactively protect against new threats without requiring an update. Sophos customers have been protected against W32/MyDoom-AJ (detected as W32/MyDoom-Gen) since version 3.92 Sophos's anti-virus products include Genotype ™ detection technology, which can proactively protect against new threats without requiring an update. Sophos customers have been protected against W32/MyDoom-AJ (detected as W32/MyDoom-Gen) since version 3.92

W32/MyDoom-AJ is a mass-mailing worm with IRC backdoor functionality which can also infect computers vulnerable to the LSASS (MS04-011) exploit.

When first run the worm copies itself to the Windows system folder as mathchk.exe and creates the following registry entries so as to auto-start:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
RealPlayer Ath Check=
mathchk.exe

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices
RealPlayer Ath Check=
mathchk.exe

HKLM\Software\Microsoft\OLE
RealPlayer Ath Check=
mathchk.exe

HKLM\System\CurrentControlSet\Control\Lsa\
RealPlayer Ath Check=
mathchk.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
RealPlayer Ath Check=
mathchk.exe

HKCU\Software\Microsoft\OLE
RealPlayer Ath Check=
mathchk.exe

HKCU\System\CurrentControlSet\Control\Lsa
RealPlayer Ath Check=
mathchk.exe

The worm will attempt to harvest email addresses from files on the local hard disk.

Emails sent by W32/MyDoom-AJ have the following characteristics:

Subject line chosen from one of the following, possibly in all uppper case or all in lower case:

Good day
Hello
Server Report
Status
<blank>

Message text chosen from:

Mail transaction failed. Partial message is available.
The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.
The message contains Unicode characters and has been sent as a binary attachment.
The original message was included as an attachment.
<junk>

Attached filename chosen from the following with an extension chosen from (bat cmd exe scr pif zip):

body
data
doc
document
file
message
readme
text

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