W32/Mytob-DS

Please follow the instructions for removing worms.

Replace the Hosts file from a backup or edit it in Notepad to remove the changes that the worm has made.

You will also need to edit the following registry entries, if they are present. Please read the warning about editing the registry.

At the taskbar, click Start|Run. Type 'Regedit' and press Return. The registry editor opens.

Before you edit the registry, you should make a backup. On the 'Registry' menu, click 'Export Registry File'. In the 'Export range' panel, click 'All', then save your registry as Backup.

Locate the HKEY_LOCAL_MACHINE entries:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices

and remove any reference to any file you deleted.

Each user has a registry area named HKEY_USERS\[code number indicating user]\. For each user locate the entry:

HKU\[code number]\Software\Microsoft\Windows\
CurrentVersion\Run\

and remove any reference to any file you deleted.

Close the registry editor.

W32/Mytob-DS is a worm and IRC backdoor Trojan for the Windows platform.

W32/Mytob-DS spreads to other network computers by exploiting common buffer overflow vulnerabilites, including LSASS (MS04-011).

W32/Mytob-DS runs continuously in the background, providing a backdoor server which allows a remote intruder to gain access and control over the computer via IRC channels.

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

Subject line:

Error
Status
Server Report
Mail Transaction Failed
Mail Delivery System
hello
Good day
<blank>
<random characters>

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 extentions 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-DS harvests email addresses from files on the infected computer and from the Windows address book.

The following patches for the operating system vulnerability exploited by W32/Mytob-DS can be obtained from the Microsoft website:

MS04-011

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-DS (detected as W32/Mytob-Fam) since version 3.93. W32/Mytob-DS is a worm and IRC backdoor Trojan for the Windows platform.

W32/Mytob-DS spreads to other network computers by exploiting common buffer overflow vulnerabilites, including LSASS (MS04-011).

W32/Mytob-DS runs continuously in the background, providing a backdoor server which allows a remote intruder to gain access and control over the computer via IRC channels.

When first run W32/Mytob-DS copies itself to:

\funny_pic.scr
\my_photo2005.scr
\see_this!!.scr
<System>\taskgmr.exe

and creates the file \hellmsn.exe.

The file hellmsn.exe is detected as W32/Mytob-D.

The following registry entries are created to run taskgmr.exe on startup:

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

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
WINTASK
taskgmr.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
WINTASK
taskgmr.exe

Registry entries are set as follows:

HKCU\SYSTEM\CurrentControlSet\Control\Lsa
WINTASK
taskgmr.exe

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
WINTASK
taskgmr.exe

HKCU\Software\Microsoft\OLE
WINTASK
taskgmr.exe

HKLM\SOFTWARE\Microsoft\Ole
WINTASK
taskgmr.exe

W32/Mytob-DS modifies the HOSTS file, changing the URL-to-IP mappings for selected websites, therefore preventing normal access to these sites. The new HOSTS file will typically contain the following:

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-DS have the following characteristics:

Subject line:

Error
Status
Server Report
Mail Transaction Failed
Mail Delivery System
hello
Good day
<blank>
<random characters>

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 extentions 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-DS harvests email addresses from files on the infected computer and from the Windows address book.

The following patches for the operating system vulnerability exploited by W32/Mytob-DS can be obtained from the Microsoft website:

MS04-011

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-DS (detected as W32/Mytob-Fam) since version 3.93.