Summary
The Feedel trojan is downloaded onto a system by a separate downloader program, which will then proceed to execute Feedel. We detected the downloader as Trojan-Downloader:W32/Agent.
Removal
In most reported cases, the payload stored in the final encrypted section of the Feedel trojan's code is a LinkOptimizer.A tool for removing the LinkOptimizer is available from:
- LinkOptimizerRemovalTool.zip (Not signed by F-Secure)
To protect themselves from deletion, LinkOptimizer variants modify their file security permissions and registry key. Additional steps are required to successfully remove them from the system.
- Finding the Sample
- Launch the Registry Editor
- Navigate to the following:[HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe]
- Check to whic file the "Debugger" value points
Example Registry key:
- [HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe] Debugger="c:\windows\system32\jardrlmn.log"
Manual disinfection instructions
- Start cmd.exe
- Kill the explorer.exe process from Task Manager
- Kill all processes that do not have SYSTEM or NETWORK SERVICE in the User Name column, EXCEPT the cmd.exe process
- Using cmd.exe, go to the folder where the malware sample is located, for example: cd windows\system32
- Add the necessary permission to the malware sample(Example: "cacls [filename] /G Everyone:F")
- Remove the read-only and other attributes of the malware sample(Example: "attrib -r -s -h")
- Delete the malware sample using cmd.exe(Example: "del [filename]")
- Launch the Registry Editor
- Navigate to[HKLM\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe]
- Add necessary permissions to the key by right-clicking on it, then selecting Permissions and selecting the Full Control checkbox
- Delete the key from the Registry
- Start explorer.exe
- Restart the system and check the Registry again. If the registry key is not present, the infection has been successfully removed
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 updatesFirst, check if your F-Secure security program is using the latest updates, then try scanning the file again.
- Submit a sampleAfter 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 scanningIf 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.
Technical Details
- https://[...]/pix/[filename].gif
Execution
- C:\%temp%\10874359.exeC:\Windows\Temp\10874359.exe
Protect your devices from malware with F‑Secure Total
Protecting your devices from malicious software is essential for maintaining online security. F‑Secure Total makes this easy, helping you to secure your devices in a brilliantly simple way.
- Award‑winning antivirus and malware protection
- Online browsing, banking, and shopping protection
- 24/7 online identity and data breach monitoring
- Unlimited VPN service to safeguard your privacy
- Password manager with private data protection
Choose how many devices you want to protect to get started.
- Free customer support
- Cancel anytime
- The trial does not obligate you to buy the product
After 30 days your subscription will renew automatically for one year at €69.99.
)
)
More Support
Community
Ask questions in our Community.
User guides
Check the user guide for instructions.
Contact Support
Chat with with or call an agent.
Submit a Sample
Submit a file or URL for analysis.