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.
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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.
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:
where "%WinSysDir%" represents Windows System directory.
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:
The worm avoids sending emails to email addresses that contain any of the following substrings:
The subject of infected emails is selected from the following variants:
The body text of infected emails is selected from the following variants:
my pics...*sexy*. Heheh! ;)
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:
The extension of an infected file can be any of the following:
The worm fakes the sender's address. It uses the following list of names to compose the fake address:
It uses the following list of domain names to compose the fake address:
The worm kills processes if it finds any of the following substrings in their names:
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.