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 action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.



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:  		  

The <worm's file name> 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 Details: Alexey Podrezov and Katrin Tocheva, December 15th, 2003


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