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Category: Malware

Type: Trojan-Downloader

Aliases: Trojan-Downloader:W32/Renos.Gen


Trojan-Downloader:W32/Renos.GEN is a generic detection for variants in the Trojan-Downloader:W32/Renos family.

Generic detections are broad patterns of code or behavior that are used by security software to identify programs or files. If you suspect the detected file was incorrectly identified, go to: Removal: Resolve a False Positive.


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.

Resolve a False Positive

Security programs will sometimes unintentionally identify a clean program or file as malicious if its code or behavior is similar to a known harmful program or file. This is known as a False Positive. In most cases, a False Positive is fixed in a subsequent database release. If you suspect the detected file is a False Positive, you can:

Knowledge Base

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About the product

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

Contact Support

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

Renos variants are trojan-downloaders that download rogueware onto the system. The trojan may arrive on the system as part of another malware's payload, from a user-initiated download, or through other means. The downloaded programs attempt to persuade the user to buy a particular rogue antispyware application by pretending that the system is infected with spyware.


On installation, the trojan drops the file

  • %WINDOWS%/system32/brastk.exe

and then creates a launchpoint for it. The brastk.exe file then attempts to download another file from a remote server.


On execution, this trojan will modify registry keys in order to bypass the Windows firewall, then download a rogue antispyware application from a remote server and save it onto the system, most commonly at:

  • %windir%\system32\winil104552502.exe

The actual save location may vary depending on the variant.

The malware subsequently creates a system tray icon that periodically displays the following message:

"Your computer is infected!

Windows has detected spyware infection!
 It is recommended to use special antispyware tools to prevent data loss.

Windows will now download and install the most up-to-date antispyware for you.
 Click here to protect your computer from spyware!"

Clicking on the message will launch the downloaded rogue antispyware application.