W32/Mytob-Y

Please follow the instructions for removing worms.

Please read the instructions for removing W32/Mytob-Y.

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

W32/Mytob-Y is a mass-mailing worm and backdoor Trojan that targets users of Internet Relay Chat programs.

The worm is capable of spreading itself using the LSASS (MS04-011) exploit vulnerability.

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

HKCU\Software\Microsoft\Ole
Windows Service XP
XpFirewall.exe

HKLM\SOFTWARE\Microsoft\Ole
Windows Service XP
XpFirewall.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Windows Service XP
XpFirewall.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Windows Service XP
XpFirewall.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
Windows Service XP
XpFirewall.exe

HKCU\SYSTEM\CurrentControlSet\Control\Lsa
Windows Service XP
XpFirewall.exe

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
Windows Service XP
XpFirewall.exe

W32/Mytob-Y copies itself to the drive C root folder as:

funny_pic.scr
my_photo2005.scr
see_this!!.scr

The worm also appends the following mappings to the %SYSTEM%\DRIVERS\ETC\HOSTS file to deny access to anti-virus and 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-Y have the following characteristics:

Subject line:

Error
Status
Server Report
Mail Transaction Failed
Mail Delivery System
hello
<random>

Message text:

Here are your banks documents.

Mail transaction failed. Partial message is available.

The message contains Unicode characters and has been sent as a binary attachment.

The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.

The original message was included as an attachment.

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

The worm also attempts to set up an FTP server as well as act as an Internet proxy via GET HTTP commands.

W32/Mytob-Y also drops a file C:\hellmsn.exe. This file is being detected by Sophos as W32/Mytob-D.