F-Secure Virus Descriptions : Randex.Q

[Summary] | [Detailed Description] | [Detection]

NAME:	Randex.Q
ALIAS:	W32.Randex.Q, W32/Randex.Q, Worm.Randex.Q, Backdoor.SDBot.gen

Summary

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.

Detailed Description

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:

 \Admin$\system32\MSL32.exe
 \c$\winnt\system32\MSL3232.exe

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.

Back to the Top

Detection

F-Secure Anti-Virus already detects this worm generically as 'Backdoor.SDBot.gen'.

Back to the Top

Technical Details: Alexey Podrezov; 28th of November, 2003;

F-Secure Corporation