W32/Mytob.S Worm

 Virus Information - W32/Mytob.S Worm:

W32/Mytob.S is a mass mailing worm. This worm is a variant of W32/Mytob.A. The worm will infect Windows systems. The worm spreads through email.

The infected email carries a spoofed 'From' address picked up randomly from the infected system.

The subject of the infected mail will be any one of the following;

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

The infected attachment will be any one of the following;

message
document
doc
body
data
file
text
test
readme

with any one of these extensions;

pif, scr, zip, bat, cmd, exe.

The body of the infected mail will be any one of the following;

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.

Here are your banks documents.

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

The original message was included as an attachments.

Upon execution of the infected attachment, the worm copies itself as stagmr.exe in the Windows System folder.

It also drops funny_pic.scr, my_photo2005.scr, see_this!!.scr files in the root of Windows installed folder.

The worm modifies registry at the following location to load itself during each startup.

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

To propagate itself, the worm scans the files having the following extensions and collects all the available email addresses from the infected system.

adb, asp, dbx, htm, php, pl, sht, tbb, wab.

It also collects email addresses from the Temporary Internet Files folder.

The worm mails itself to these addresses using its own SMTP engine.

The worm tries to block access to some of the security related websites.