Threat Description

Memas

Details

Aliases: Memas, I-Worm.Memas, W32/Memas@mm, W32.Memas@mm
Category: Malware
Type:
Platform: W32

Summary



Memas is a 2-component e-mail worm. It is also capable of infecting executable files. The worm spreads itself as an executable attachment in e-mails that are sent to all e-mail addresses from an infected computer's Address Book.



Removal



Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.



Technical Details



Memas worm usually arrives as an executable e-mail attachment. When the worm's file is run, it drops a Visual Basic script file as C:\FEMAIL.VBS and activates it.

The Visual Basic Script part is the one that does the mass mailing of the worm. It first check for the presence of a Windows registry key:

[HKCU\Software\Microsoft\Windows\CurrentVersion\MeMeMasr?]

and if it does not exist, it creates such key. Thus the worm will mass mail once per infected computer.

Next, it uses Outlook Application to get all addresses from the address book and mass mail a copy of the worm in messages that look as follows:

     Subject: "Hi Friend"
        Body: "Please See The Attachment"
        Attachment: <worm's file name>
		

The &lt;worm's file name&gt; is the name of the worm's file that depends on the name of the infected attachment that was originally run by a user.

To hide this action the Visual Basic Script deletes all sent emails.

The worm is capable of infecting executable files on an infected computer. It scans all available drives and prepends itself to all found executable files. However, the worm does not infect files in folders that have the following names:

windows
 system32
 system
 

The worm also doesn't infect files with the following names:

IEXPLORE.EXE
 ccApp.exe
 ccRegVfy.exe
 

All infected files are marked by adding the 'ShohdiEmail' line to their ends. When an infected file is run, the worm takes control, extracts the original file's contents to the same folder, but with .SEL extension and runs the extracted file.

The worm can display a mixed English-Arabic message.



Detection


Detection was published on December 8th in the following F-Secure Anti-Virus update:
Detection Type: PC
Database: 2003-12-08_01



Description Created: Alexey Podrezov and Katrin Tocheva, December 15th, 2003


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