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MyDoom.AC

Classification

Category: Malware

Type: Email-Worm

Aliases: MyDoom.AC, .Mydoom.w, W32/Mydoom.AC@mm

Summary


A new variant of MyDoom worm - Mydoom.AC, was found in the middle of September 2004. This worm variant can spread in emails as a fake FlashEcard virtual postcard.

Removal


Automatic action

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Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

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Submit a sample

Submit a file or URL for further analysis.

Technical Details


The worm is a PE executable file 23040 bytes long packed with PECompact and PECBundle file compressors and modified by PE_Patch. The unpacked file's size is over 61 kilobytes.

Installation to system

When run, the worm starts Internet Explorer and goes to 'www.microsucks.com' website as a disguise.

Then the worm creates a mutex 'holla_back_bitches', copies itself as SYSHOSTS.EXE to Windows System Directory and creates a startup key for that file in System Registry:

  • [HKCU\Software\Microsoft\Windows\CurrentVersion\Run] "MS Updates" = "%WinSysDir%\syshosts.exe"

where "%WinSysDir%" represents Windows System directory.

Spreading in emails

The worm spreads by sending its infected attachment to all email addresses found on an infected computer. The worm looks for email addresses in Windows Address Book and in the files with the following extensions:

  • txt
  • htm
  • html
  • sht
  • php
  • eml
  • msg
  • asp
  • dbx
  • tbb
  • adb
  • pl
  • wab

The worm avoids sending emails to email addresses that contain any of the following substrings:

  • icrosof
  • syma
  • msn
  • hotmail
  • anda
  • opho
  • borlan
  • npris
  • xample
  • mydom
  • @domai
  • ruslis
  • .gov
  • .gov
  • .mil
  • @foo
  • berkeley
  • unix
  • math
  • bsd
  • mit.e
  • gnu
  • fsf.
  • ibm
  • oogle
  • kernel
  • linux
  • fido
  • senet
  • @ian
  • ripe
  • isi.e
  • arin.
  • rfc-ed
  • isc.o
  • ecur
  • acketst
  • pgp
  • tanford.e
  • utgers.ed
  • ample
  • info
  • root@
  • ostmaster@
  • ebmaster@
  • you
  • ugs@
  • ating@
  • ontact@
  • soft
  • rivacy
  • ervice
  • help
  • ubmit@
  • feste
  • cert
  • page
  • upport
  • ntivi
  • istser
  • ertific
  • ccoun
  • spm
  • Spam
  • SPAM
  • spam
  • abuse
  • cafee
  • @messagelab
  • @avp
  • kasp
  • winzip
  • winrar
  • pdate
  • irus
  • ahoo
  • buse@
  • sale

The subject of infected emails is selected from the following variants:

  • album
  • You've got a Virtual Postcard!

The body text of infected emails is selected from the following variants:

my pics...*sexy*. Heheh! ;)

or

You have just received a new postcard from Flashecard.com!

From:

To pick up your postcard follow this web address
http://www.flashecard.com.viewcard.main.ecard.php?2342
or click the attached link.
We hope you enjoy your postcard, and if you do, please
take a moment to send a few yourself!

(Your message will be available for 30 days.)

Please visit our site for more information.
http://www.flashecard.com

The worm can send itself as an executable attachment or in a ZIP archive with one of the following names:

  • photos_album
  • www.flashecard.com?postcard=viewcard?download

The extension of an infected file can be any of the following:

  • .scr
  • .html.scr

The worm fakes the sender's address. It uses the following list of names to compose the fake address:

  • Jennifer
  • Barbara
  • Linda
  • Susan
  • Eric
  • Kevin
  • Mary
  • Robert
  • John
  • Maria
  • Alex
  • Pamela
  • Anna
  • Andrew
  • Fred
  • Jack
  • James
  • Julie
  • Debby
  • Claudia
  • Matt
  • Brent

It uses the following list of domain names to compose the fake address:

  • @aol.com
  • @hotmail.com
  • @yahoo.com
  • @msn.com
  • @excite.com
  • @mail.com
Killing processes

The worm kills processes if it finds any of the following substrings in their names:

  • regedit
  • task
  • msconfig
  • AV
  • MC
  • Av
  • Mc
  • av
  • mc
  • IEFrame
  • nti
  • iru
  • ire
  • cc
  • ecu
  • can
  • scn
  • KV
  • fr
Payload

After December 1st, 2004, 01:01:01 the worm shuts down Windows on an infected computer after its file is started. As a result a user can not log in any more.