Feebs

Classification

Malware

Trojan

W32

Feebs, W32/Kmax, W32.Feebs, Worm.Win32.Feebs.gen

Summary

Feebs is a family of worms that spread using email or P2P networks. Feebs usually comes as HTML application file (HTA) that installs the worm on infected system. Feebs hides itself using rootkit techniques.

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

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.

For more Support

Knowledge Base

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User Guide

See the user guide for your 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

System installation

When the HTML application file (HTA) is opened, it drops the worm main executable file in 'C:\Command.exe' and executes it. The EXE file drops a file with single letter 'a'-'z' on C-drive and activates it. That file is the worm main DLL component. When active, it creates the following files:

  • %System%\ms[random]32.dll %System%\ms[random]32.exe

The main DLL component also creates the following registry values for making sure the worm is activated on system startup:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad] "%System%\ms[random]32.dll" = "{[random CLSID]}"
  • [HKML\CLSID\{[random CLSID]}\InprocServer32] "(default)" = "%System%\ms[random]32.dll"

Spreading

Feebs can spread sending email attachments containing the HTA dropper. The highly polymorphic HTA file is generated each time when the worm sends it. Feebs can also copy itself on shared folders used by some P2P applications.

Payload

Feebs starts HTTP server listening on port 80 for serving infected HTA files. The worm also starts server on random port which allows the attacker to control infected system. The random port is reported back to attacker using ICQ and HTTP. Feebs also tries to disable several security-related applications.

Rootkit functionality

Feebs can hide its files, registry keys and network connections by utilizing rootkit techniques. The worm main DLL component is injected to all running processes and used for hooking the system library functions.