Threat Description



Aliases: Backdoor:W32/SubSeven, SubSeven, Backdoor.SubSeven
Category: Malware
Type: Backdoor
Platform: W32


A remote administration utility that bypasses normal security mechanisms to secretly control a program, computer or network.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.


Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

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

Technical Details

Backdoor:W32/SubSeven is a backdoor program that allows a remote user to perform a large range of actions on the affected system.

The first samples of this backdoor were not packed, but later some packed versions appeared which were not easy to detect with contemporary anti-virus programs that had no Win32 'Aspack' file compressor unpacking support.

SubSeven backdoor was first discovered in May, 1999. The backdoor is usually distributed under different names via newsgroups and e-mails.


When run, the backdoor copies itself to the Windows directory with the original name of the file it was run from or as SERVER.EXE, KERNEL16.DL, RUNDLL16.COM, SYSTEMTRAYICON!.EXE or WINDOW.EXE (names are different in different versions of SubSeven).

Then it unpacks a single DLL file to the Windows System directory - WATCHING.DLL (some versions don't do this). After that the backdoor patches Windows Registry so that its main application will be run during every Windows bootup (Run or RunServices keys). Finally, it creates and modifies some other Registry keys. The backdoor can also install itself to the system by modifying either the WIN.INI or the SYSTEM.INI file.

The latest versions of the SubSeven backdoor drop a small starter program (usually WINDOS.EXE) and register it to be run when any EXE file is started in Windows. By doing this the backdoor ensures that its copy is always in the memory. For specific instructions of how to disinfect these versions please see the bottom of the page.

All the recent versions of SubSeven are supplied with a server configuration utility that allows it to customize server part capabilities - installation method, custom startup message, etc. This method was first introduced by the Back Orifice 2000 backdoor and it allows much more flexibility to backdoors.


If the SubSeven backdoor task is being active in the memory (and invisible in Task Manager), it looks for TCP/IP connections and if they are established it listens to TCP/IP ports for commands from a client part.

Subseven also tries to use ICQ, IRC and different e-mail accounts to notify the author that his victims are online.

SubSeven's initial version had the following 113 capabilities:

 Fun Manager   ------------------   1. Open Web Browser to specified location.   2. Restart Windows.   3. Reverse Mouse buttons.   4. Hide Mouse Pointer.   5. Move Mouse.   6. Mouse Trail Config.   7. Set Volume.   8. Record Sound file from remote mic.   9. Change Windows Colors / Restore.   10. Hung up Internet Connection.  11. Change Time.   12. Change Date.   13. Change Screen resolution.   14. Hide Desktop Icons / Show   15. Hide Start Button / Show   16. Hide taskbar / Show   17. Opne CD-ROM Drive / Close   18. Beep computer Speaker / Stop   19. Turn Monitor Off / On   20. Disable CTRL+ALT+DEL / Enable   21. Turn on Scroll Lock / Off   22. Turn on Caps Locl / Off   23. Turn on Num Lock / Off     Connection Manager   -----------------------------   1. Connect / Disconnect   2. IP Scanner   3. IP Address book   4. Get Computer Name   5. Get User Name   6. Get Windows and System Folder Names   7. Get Computer Company   8. Get Windows Version   9. Get Windows Platform   10. Get Current Resolution   11. Get DirectX Version   12. Get Current Bytes per Pixel settings   13. Get CPU Vendor   14. Get CPU Speed   15. Get Hard Drive Size   16. Get Hard Drive Free Space   17. Change Server Port   18. Set Server Password   19. Update Server   20. Close Server   21. Remove Server   22. ICQ Pager Connection Notify   23. IRC Connection Notify   24. E-Mail Connection Notify     Keyboard Manager   --------------------------   1. Enable Key Logger / Disable   2. Open Key Logger in a remote Window   3. Clear the Key Logger Windows   4. Collect Keys pressed while Offline   5. Open Chat Victim + Controller   6. Open Chat among all connected     Controllers   --------------   1. Windows Pop-up Message Manager   2. Disable Keyboard   3. Send Keys to a remote Window     Misc. Manager   --------------------   1. Full Screen Capture   2. Continues Thumbnail Capture   3. Flip Screen   4. Open FTP Server   5. Find Files   6. Capture from Computer Camera   7. List Recorded Passwords   8. List Cached Passwords   9. Clear Password List   10. Registry Editor   11. Send Text ot Printer     File Manager   ------------------   1. Show files/folders and navigate   2. List Drives   3. Execute Application   4. Enter Manual Command   5. Type path Manually   6. Download files   7. Upload files   8. Get File Size   9. Delete File   10. Play *.WAV   11. Set Wallpaper   12. Print *.TXT\*.RTF file   13. Show Image     Window Manager   ------------------------   1. List visible windows   2. List All Active Applications   3. Focus on Window   4. Close Window   5. Disable X (close) button   6. Hide a Window from view.   7. Show a Hidden Window   8. Disable Window   9. Enable Disabled Window     Options Menu   --------------------   1. Set Quality of Full Screen Capture   2. Set Quality of Thumbnail Capture   3. Set Chat font size and Colors   4. Set Client's User Name   5. Set local 'Download' Directory   6. Set Quick Help   7. Set Client Skin   8. Set Fun Manager Skin     Edit Server   --------------   1. PreSet Target Port   2. PreSet server Password   3. Attach EXE File   4. PreSet filename after installation   5. PreSet Registry Key   6. PreSet Autostart Method:   Registry: Run   Registry: RunSevices   Win.ini   Less known method   7. PreSet Fake error message   8. PreSet Connection Notify Username   9. PreSet Connection Notify ICQ#   10. PreSet Connection Notify E-Mail   11. PreSet Connection Notify IRC Chan.   12. PreSet IRC Port   13. Change Server *.exe Icon    


Suspect a file or URL was wrongly detected? Submit a sample to our Labs for analysis

Submit Now

Give And Get Advice

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

Learn More