Summary

Randex is a network worm that has backdoor features. This variant of Randex appeared on 8th of September 2003.

Additional Details

The worm's file is a Windows PE executable 73728 bytes long. The worm's file is not compressed. Some text strings in the worm are encrypted with a simple cryptoalgorithm.

When the worm's file is started it first looks for and deletes 'winnt32.dat' file in Windows System folder. Then the worm gets API addresses of different Windows functions and checks whether it is already installed on this computer. If not, the worm copies its file as 'netd32.exe' to Windows System directory and creates a startup key for it in the Registry:

 [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
 "Microsoft Network Daemon for Win32" = "netd32.exe"

 [HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices]
  "Microsoft Network Daemon for Win32" = "netd32.exe"

After the worm starts, it tries to connect to an IRC server (two hardcoded names) and creates a bot in the specific channel (hardcoded name) on this server. Through this bot a hacker can control the worm's behaviour. A hacker can perform the following actions:

 1. Log in and out of the bot
 2. Display and clear masters list
 3. Terminate own process
 4. Generate another random nickname for the bot
 5. Connect and disconnec from IRC server
 6. List active threads
 7. Show log file
 8. Get connection type
 9. Get system information
 10. Start and stop NTScan
 11. Uninstall the worm
 12. Delete the WINNT32.DAT file
 13. Terminate theads or a selected thread
 14. Join and part from a channel, change bot's nickname
 15. Open or run a specified file
 16. Get DNS info
 17. Open a specified URL
 18. Perform SYN flood
 19. Send private message from a bot
 20. Create clones
 21. Redirect traffic for specific port
 22. Download files from a specified URL
 23. Execute specified files
 24. Change channel mode
 25. Update the worm from a specified URL
 26. Destroy current bot
 27. Perform a DoS (Denial of Service) attack
 28. Steal CD keys for the following games:

 HalfLife
 Unreal Tournament 2003
 Battlefield 1942
 Battlefield 1942: Road To Rome
 Command and Conquer: Generals

When instructed to do a NTScan, the worm copies itself to Windows System folder as WINNT32.DAT, generates random IP addresses and tries to connect to them. The worm tries to retrieve network user names and connect using them, but in case this fails, the worm will try to connect as Administrator. Once connected the worm tries to access to IPC$ share on remote computer and to copy itself to the following locations as NETD32.EXE file:

 \ADMIN$\system32\netd32.exe
 \C$\WINNT\system32\netd32.exe

The above locations correspond to System32 folders of NT-based operating systems.

After copying its file, the worm creates a scheduled network task to start the copied worm's file on remote computer. When this happens, a remote computer becomes infected with the worm.

Detection

Detection of Randex.J worm was added in the following updates:

Version=2003-09-09_03

Technical Details: Alexey Podrezov; 11th of September, 2003;