Home > Threat descriptions >



Category: Malware

Type: Worm

Aliases: Glieder.I, Trojan.Win32.Glieder.i, W32/Glieder.I, TrojanDropper.Win32.Small.kv, TrojanDownloader.Win32.Agent.cj


Yet another Glieder variant has been spammed. The origin is an email message sent to many people. The message contains an attachment named FOTOS.ZIP. Inside the ZIP archive there is an HTML portion that uses a common exploit to launch an EXE file named CALC.EXE, which is also located inside the archive.


Automatic action

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

Knowledge Base

Find the latest advice in our Community Knowledge Base.

About the product

See the manual for your F-Secure product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details

Once the CALC.EXE file is launched it copies itself to the Windows System32 directory under the name DORIOT.EXE and adds Registry keys under:


to ensure the trojan is stared upon reboot. A file named GDQFW.EXE is then dropped onto the Windows System32 directory. This file is then injected into Explorer.exe process space through process memory manipulation. The dropper terminates at this stage.

The injected code from GDQFW.EXE is active while Explorer.exe is active. It performs various tasks which include monitoring various security related update programs and terminating them; checking predefined list of URLs for a particular file and if present - downloading and executing it. It also manipulates with cached URLs on the user's machine.