W32/Mytob-Z

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 please read the instructions for removing W32/Mytob-Z.

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/Mytob-Z (detected as W32/MyDoom-Gen) since version 3.92.

W32/Mytob-Z is a mass-mailing worm and Trojan with an IRC backdoor.

W32/Mytob-Z is capable of spreading through operating system vulnerabilities such as LSASS (MS04-011).

W32/Mytob-Z harvests email addresses from files on the infected computer and from the Windows address book. 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/Mytob-Z (detected as W32/MyDoom-Gen) since version 3.92.

W32/Mytob-Z is a mass-mailing worm and Trojan with an IRC backdoor.

W32/Mytob-Z is capable of spreading through operating system vulnerabilities such as LSASS (MS04-011).

When first run, W32/Mytob-Z copies itself to the Windows system folder as msmgrxp.exe and creates the following registry entries:

HKCU\Software\Microsoft\OLE
WINTASK
msmgrxp.exe

HKCU\System\CurrentControlSet\Control\Lsa
WINTASK
msmgrxp.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
WINTASK
msmgrxp.exe

HKLM\Software\Microsoft\OLE
WINTASK
msmgrxp.exe

HKLM\System\CurrentControlSet\Control\Lsa
WINTASK
msmgrxp.exe

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
WINTASK
msmgrxp.exe

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices
WINTASK
msmgrxp.exe

W32/Mytob-Z copies itself to the root folder as:

my_photo2005.scr
see_this!!.scr
funny_pic.scr

The worm also drops a helper component to C:\hellmsn.exe which is detected by Sophos as W32/Mytob-D.

W32/Mytob-Z also appends the following to the HOSTS file to deny access to security-related websites:

127.0.0.1 www.symantec.com
127.0.0.1 securityresponse.symantec.com
127.0.0.1 symantec.com
127.0.0.1 www.sophos.com
127.0.0.1 sophos.com
127.0.0.1 www.mcafee.com
127.0.0.1 mcafee.com
127.0.0.1 liveupdate.symantecliveupdate.com
127.0.0.1 www.viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 f-secure.com
127.0.0.1 www.f-secure.com
127.0.0.1 kaspersky.com
127.0.0.1 www.avp.com
127.0.0.1 www.kaspersky.com
127.0.0.1 avp.com
127.0.0.1 www.networkassociates.com
127.0.0.1 networkassociates.com
127.0.0.1 www.ca.com
127.0.0.1 ca.com
127.0.0.1 mast.mcafee.com
127.0.0.1 my-etrust.com
127.0.0.1 www.my-etrust.com
127.0.0.1 download.mcafee.com
127.0.0.1 dispatch.mcafee.com
127.0.0.1 secure.nai.com
127.0.0.1 nai.com
127.0.0.1 www.nai.com
127.0.0.1 update.symantec.com
127.0.0.1 updates.symantec.com
127.0.0.1 us.mcafee.com
127.0.0.1 liveupdate.symantec.com
127.0.0.1 customer.symantec.com
127.0.0.1 rads.mcafee.com
127.0.0.1 trendmicro.com
127.0.0.1 www.microsoft.com
127.0.0.1 www.trendmicro.com

Emails sent by W32/Mytob-Z have the following characteristics:

Subject line:

Error
Status
Server Report
Mail Transaction Failed
Mail Delivery System
hello
Good day

Message text:

Here are your banks documents.

The original message was included as an attachment.

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.

Mail transaction failed. Partial message is available.

The attached file consists of a base name followed by the extensions BAT, CMD, PIF, SCR, EXE or ZIP. The worm may optionally create double extensions where the first extension is DOC, TXT or HTM and the final extension is PIF, SCR, EXE or ZIP.

W32/Mytob-Z harvests email addresses from files on the infected computer and from the Windows address book.