W32/Mytob-AG

Please follow the instructions for removing worms.

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-AG is a mass-mailing network worm with IRC backdoor functionality.

W32/Mytob-AG connects to a preconfigured IRC server and joins a channel in which it can await further instructions.

W32/Mytob-AG attempts to spread to randomly-chosen IP addresses by exploiting the LSASS vulnerability (MS04-011). The patch for this vulnerability can be obtained from the Microsoft website:

MS04-011. W32/Mytob-AG is a mass-mailing network worm with IRC backdoor functionality.

W32/Mytob-AG copies itself to the file w32NTupdt.exe in the Windows system folder and creates the following registry entries in order to run at logon:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
A New Windows Updater
w32NTupdt.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
A New Windows Updater
w32NTupdt.exe

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
A New Windows Updater
w32NTupdt.exe

HKLM\Software\Microsoft\OLE
A New Windows Updater
w32NTupdt.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
A New Windows Updater
w32NTupdt.exe

HKCU\SYSTEM\CurrentControlSet\Control\Lsa
A New Windows Updater
w32NTupdt.exe

HKCU\Software\Microsoft\OLE
A New Windows Updater
w32NTupdt.exe

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

Subject: one of

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

Body: one of

Here are your banks documents.

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

Mail transaction failed. Partial message is available.

Attachment name: one of

document
readme
doc
text
file
data
test
message
body
<random text>

Attachment extension: one of

pif
scr
exe
cmd
bat

The attached file may have a double extension.

W32/Mytob-AG connects to a preconfigured IRC server and joins a channel in which it can await further instructions.

W32/Mytob-AG attempts to spread to randomly-chosen IP addresses by exploiting the LSASS vulnerability (MS04-011). The patch for this vulnerability can be obtained from the Microsoft website:

MS04-011.