W32/Mytob.J 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;

(Blank Subject)
Good day
hello
status
test
Mail Transaction Failed
error
SERVER REPORT
Mail Delivery System
(Variable String)

The infected attachment will be any one of the following;

message
document
doc
body
data
file
test
text
readme
(Varible String)

The extension of the infected attachment will be single or double, the first extension can be any one of these;

doc, txt, htm, html.

The second extension can be any one of these;

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

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.

(Variable String)

Upon execution of the infected attachment, the worm copies itself as sys32.exe in the Windows System folder.

It also drops hellmsn.exe in Windows Installed folder. The worm copies itself as funny_pic.scr, my_photo2005.scr and see_this!!.scr in the 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.

This worm first appeared on 24th March, 2005.

 Other names of W32/Mytob.J Worm:

This Worm is also known as W32.Mytob.K@mm , W32/Mytob-F, Mytob.I, Net-Worm.Win32.Mytob.j.