Trojan.AOL.Buddy

Classification

Malware

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Trojan.AOL.Buddy, W95/PennyTools.Trojan, PennyTools, Buddy

Summary

The 'W95/PennyTools.Trojan' or 'Trojan.Aol.Buddy' is an AOL password stealing trojan. Three versions are currently known (by May 1999). One version was spread inside MS Word document advertising access to AOL for free. If a user clicks on AOL logo in the document his system becomes infected. Another version is spread in another word document that has only setup icon.

Removal

To disinfect the trojan manually a user should exit to DOS and manually remove all five trojan files from locations specified above. As trojan files and directories have hidden attribute the ATTRIB utility should be used before deleting to make files and directories 'visible'.

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.

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Submit a sample

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Technical Details

This trojan uses a tricky way of installing itself to system. It uses 5 different ways at the same time to make disinfection more difficult:

1. Through Registry by modifying RUN key to launch C:\COMMAND.EXE

 hidden file which is a trojan's body

2. Through SYSTEM.INI by adding a screensaver reference routine

 to C:\Windows\System\WINSAVER.EXE - the system will become

infected when screen saver starts.

3. Through WIN.INI - by adding to execution of C:\America Online

 4.0\BUDDYLIST.EXE hidden file to LOAD= string with more than

80 spaces in front of line to hide it

4. Again through WIN.INI - by adding to execution of

 C:\Windows\System\NortonAntiVir\REGISTRYREMINDER.EXE hidden

file to RUN= string

5. Through Windows startup directory - by placing AIM

 REMINDER.EXE file in \Windows\Start Menu\Programs\Startup\

folder.

Also a DLL is created in Windows\System folder with the name VCLCNTL.DLL but it contains some text data for the trojan, not DLL code. When Windows is started the trojan is also started (one of steps 1-5) and remains active during all Windows session. It sends user's AOL login and password as email to qware4019@hotmail.com, ha015312@hotmail.com or liighthack@yahoo.com addresses (depending on trojan version).