Email-Worm:W32/MyDoom.K

Classification

Malware

Email-Worm

W32

MyDoom.K, I-Worm.Mydoom.j, W32/MyDoom.K@MM

Summary

MyDoom.K worm variant appeared on May 21st, 2004. It is functionally similar to MyDoom.E variant, but does not spread to Kazaa file sharing network and does not perform a DoS (Denial of Service) attack. The worm drops a backdoor component that listens on port 3127.

Removal

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

Suspect a file is incorrectly detected (a False Positive)?

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note You need administrative rights to change the settings.

Find out more

Knowledge Base

Find the latest advice in our Community Knowledge Base.

User Guide

See the user guide for your product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details

MyDoom.K worm's file is a PE executable 50176 bytes long compressed with a modified UPX file compressor. The backdoor DLL is a 4608 bytes long, also compressed with a modified UPX file compressor.

Installation to system

When the worm's file is run, it creates a separate thread that generates garbage data file and then opens it with Notepad. Then this thread terminates.

After that the worm drops SHIMGAPI.DLL file into Windows System folder. This file is a backdoor (hacker's remote access) component. It is started as a thread of Explorer from the following Registry key:

  • [HKCR\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InprocServer32]

Finally the worm installs itself to system. It copies itself as RUNDLL6.EXE file to Windows System directory and creates a startup key for this file in the Registry:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "rundll" = "%winsysdir%\rundll6.exe"

where %winsysdir% represents Windows System directory name.

Additionally the worm deletes the following Registry keys:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "SVHOST" "TaskMon"

Spreading in emails

The worm spreads itself in email messages. To locate email addresses to spread to, the worm reads Address Book file name from the Registry:

  • [HKCU\Software\Microsoft\WAB\WAB4\Wab File Name]

Then it browses through the Address Book file and collects email addresses from there. Additionally the worm looks for email addresses in files with the following extensions:

  • wab
  • pl
  • adb
  • tbb
  • dbx
  • asp
  • php
  • sht
  • htm

The worm avoids using email addresses that contain the following substrings:

  • avp
  • syma
  • icrosof
  • msn.
  • hotmail
  • panda
  • drweb
  • dials
  • sopho
  • borlan
  • inpris
  • example
  • mydomai
  • nodomai
  • ruslis
  • microsoft
  • .gov
  • gov.
  • .mil
  • foo.
  • berkeley
  • unix
  • math
  • bsd
  • mit.e
  • gnu
  • fsf.
  • ibm.com
  • google
  • kernel
  • linux
  • fido
  • usenet
  • iana
  • ietf
  • rfc-ed
  • sendmail
  • arin.
  • ripe.
  • isi.e
  • isc.o
  • secur
  • acketst
  • pgp
  • tanford.e
  • utgers.ed
  • mozilla
  • root
  • info
  • samples
  • postmaster
  • webmaster
  • noone
  • nobody
  • nothing
  • anyone
  • someone
  • your
  • you
  • me
  • bugs
  • rating
  • site
  • contact
  • soft
  • no
  • somebody
  • privacy
  • service
  • help
  • not
  • submit
  • feste
  • ca
  • gold-certs
  • the.bat
  • page
  • admin
  • icrosoft
  • support
  • ntivi
  • unix
  • bsd
  • linux
  • listserv
  • certific
  • google
  • accoun
  • www
  • spam
  • smp
  • abuse

The worm can fake the sender's email address. It composes email addresses from 2 parts: user name and domain name. Here is the list of user names that the worm uses:

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

Here is the list of domain names that the worm uses:

  • aol.com
  • msn.com
  • yahoo.com
  • hotmail.com

The subject for the infected message is selected from the following variants:

  • game
  • Ok
  • thank
  • Mail Delivery System
  • Mail Transaction Failed
  • Server Report
  • Circus
  • Error

The body of the infected message can contain one of the following:

  • test
  • The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.
  • The message contains Unicode characters and has been sent as a binary attachment.
  • Mail transaction failed. Partial message is available.

The attachment name can be one of the following:

  • document
  • readme
  • doc
  • text
  • file
  • data
  • test
  • message
  • body

The attachment can have 2 extensions. In such case the first extension can be:

  • doc
  • htm
  • txt

And the second or the only extension can be:

  • pif
  • scr
  • exe
  • cmd
  • bat

The worm can also send itseld inside a ZIP archive.

Payload

The worm drops a backdoor component that starts as a thread of Explorer and listens to port 3127 for commands from remote hackers.

Additionally the worm tries to connect to 'sipper112.netfirms.com' website. At the moment of creation of this description the site was not accessible because it exceeded its its daily bandwidth limit.