W32/Mytob.U Worm

 Virus Information - W32/Mytob.U Worm:

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

The infected mail 'From' address prefix will be any one of the following;

adam, alex, alice, andrew, anna, bill, bob, brenda, brent, brian, claudia, dan, dave, david, debby, fred, george, helen, jack, james, jane, jerry, jim, jimmy, joe, john, jose, julie, kevin, leo, linda, maria, mary, matt, michael, mike, peter, ray, robert, sam, sandra, serg, smith, stan, steve, ted, tom

the suffix after '@' character will be any one of the following domains;

hotmail.com
cia.gov
fbi.gov
yahoo.com
juno.com
msn.com
aol.com

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

Good day
hello
status
test
Mail Transaction Failed
error
Server Repoer
Mail Delivery System

The infected attachment will be any one of the following;

message
document
doc
body
data
file
test
text
readme

The extension of the infected attachment will be any one of the following;

cmd, bat, pif, scr, zip, exe, htm, tmp, doc, txt

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

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

Mail transaction failed. Partial message is available.

test

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

Here are your banks documents.

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

It also drops funny_pic.scr, my_photo2005.scr and see_this!!.scr 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

The worm attempts to locate SMTP server by appending the following prefixes to the domain names collected from the infected system. On successful SMTP server access it mails itself to the collected email addresses.

mx.
ns.
relay.
mail1.
mxs.
mx1.
smtp.
mail.
gate.