Randex (also known as SDBot) is a backdoor with network worm capabilities. This variant of Randex appeared on 28th of November 2003. It is functionally similar to previous versions, but has less features.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
More information on scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
The backdoor's file is a Windows PE executable 37376 bytes long. It is compressed with patched UPX file compressor.
When activated, the backdoor gets API addresses of different Windows functions and checks whether it is already installed on this computer. If not, the backdoor copies its file as 'msrundll.exe' to Windows System directory and creates a startup key for it in the Registry:
[HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "Microsoft Windows Kernel Functionalities" = "msrundll.exe" [HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices] "Microsoft Windows Kernel Functionalities" = "msrundll.exe"
After the backdoor starts, it tries to connect to an IRC server (one hardcoded name) and creates a bot in the specific channel (hardcoded name) on this server. Through this bot a hacker can control the backdoor's behaviour. A hacker can perform the following actions:
1. Log in and out of the bot (requires a password) 2. Terminate own process 3. Generate another random nickname for the bot 4. Connect, reconnect and disconnect from IRC server 5. Show bot status 6. Show bot ID 7. Show threads list 8. Show aliases list 9. Show log file 10. Start and stop sniffer functionality 11. Show network info 12. Show system information 13. Start and stop NTScan (spread to network) 14. Remove the bot 15. Delete the PAYLOAD,DAT file 16. Change bot's nickname 17. Join/part channels 18. Kill specific threads 19. Send SYN packets 20. Add aliases 21. Send private messages 22. Change channel mode 23. Join/part specific channel in a cycle 24. Update the backdoor 25. Start a specific file 26. Create clones 27. Download files 28. Show infected computer's IP address and connection type
When instructed to do a NTScan, the backdoor copies itself to Windows System folder as 'ms093upd.dat', generates random IP addresses and tries to connect to them. The backdoor tries to retrieve network user names and connect using them, but in case this fails, it will try to connect as Administrator.
The backdoor uses the following passwords to connect to remote computers:
admin root 1 111 123 1234 123456 654321 !@#$ asdf asdfgh !@#$% !@#$%^ !@#$%^& !@#$%^&* Guest Gast Administrateur server Administrator Beheerder super user password secret xp nt me love girl iloveyou tits pussy 2600 2800 hacker leet l337
Once connected the backdoor tries to access to IPC$ share on remote computer and to copy itself to the following locations as 'MSL32.exe' and 'MSL3232.exe' files:
The above locations correspond to System32 folders of NT-based operating systems.
After copying its file, the backdoor creates a scheduled network task to start the copied infected file on remote computer. When this happens, a remote computer becomes infected with the backdoor.
F-Secure Anti-Virus already detects this worm generically as 'Backdoor.SDBot.gen'.
Technical Details:Alexey Podrezov; 28th of November, 2003