Trojan:W32/Agent.AF

Threat description

Details

CATEGORYMalware
TYPETrojan

Summary

Trojan:W32/Agent.AF.A "locks" the machine and displays a message directing the user to send an SMS to a specified number in order to receive the password key to unlock the computer.



Removal

Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

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

Contact Support

F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Agent.AF may be considered ransomware as it hijacks the computer system and demands the user perform a specified action in order to regain control of the machine. Agent.AF may be dropped on a computer by Trojan-Dropper:W32/Blocker.A..

Execution

Agent.AF installs to the Windows temp folder. All samples analyzed so far show that the file uses the filename:

  • donX.tmp

where X is a number.The trojan then modifies the UserInit registry by adding a file path to the said registry so that it executes automatically.

  • ¢HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon Userinit = %systemfolder%\userinet.exe,

Note: The default value of this key is Userinit = %systemfolder%\userinet.exe

Activity

To take control of the computer, Agent.AF drop a batch file that forces the machine to reboot. During reboot, the batch file "locks" the computer screen. At the same time, it disables several Windows shortcut key combinations to prevent the user from regaining control over the machine, including CTRL+ALT+DEL, Alt+F4 and others.The trojan then displays the following message in a small window in the center:

The message directs the user to send an SMS containing a number key (generated by the malware) to the number 3649.

Submit a Sample

Suspect a file or URL was wrongly detected?
Send it to our Labs for further analysis

Submit a Sample

Give And Get Advice

Give advice. Get advice. Share the knowledge on our free discussion forum.

More Info