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Published Jul 20, 2004 | Updated Sep 15, 2017

Worm:Win32/Randex.H

Detected by Microsoft Defender Antivirus

Aliases: W32.Randex.D (Symantec) W32/Slanper-A (Sophos) WORM_RANDEX.D (Trend Micro) W32/Slanper.worm.gen (McAfee) Win32.Lioten.AH (CA)

Summary

Win32/Randex.H is a network worm that targets computers running certain versions of Microsoft Windows. The worm attempts to spread by randomly scanning IP addresses for computers that do not have Microsoft Security Bulletin MS03-026 installed or for writeable network shares with weak passwords. The worm also drops a backdoor proxy Trojan that acts as an HTTP proxy that allows attackers to access the infected computer.
To manually recover from infection by Win32/Randex.H, perform the following steps:
  1. Disconnect from the Internet.
  2. Restart the computer in safe mode. 
  3. End the worm processes.
  4. Delete the worm files from the computer.
  5. Delete the worm registry entries.
  6. Restart the computer.
  7. Scan network shares with an antivirus program. 
  8. Take steps to prevent re-infection.

Disconnect from the Internet

To help ensure that your computer is not actively infecting other computers, disconnect it from the Internet before proceeding. Print this Web page or save a copy on your computer; then unplug your network cable and disable your wireless connection. You can reconnect to the Internet after completing these steps.

Restart the computer in safe mode

To start your computer in safe mode
  1. Remove all floppy disks and CDs from your computer, and then restart your computer.
  2. When prompted, press F8. If Windows starts without displaying the Please select the operating system to start menu, restart your computer. Press F8 after the firmware POST process completes, but before Windows displays graphical output.
  3. From the Windows Advanced Options menu, select a safe mode option.

End the worm processes

Ending the worm process will help stop your computer from infecting other computers as well as resolve the crashing, rebooting, and performance degradation issues that the worm causes.
To end the worm process
  1. Press CTRL+ALT+DEL once and click Task Manager.
  2. Click Processes and click Image Name to sort the running processes by name.
  3. Select the process msmsgri32.exe if it exists, and then click End Process.
  4. Select the process msnetsys32.exe if it exists, and then click End Process.
  5. Select the process payload.dat if it exists, and then click End Process. 

Delete the worm files from the computer

To delete the worm files from the computer
  1. Click Start, and then click Run.
  2. In the Open field, type %Windir%\system32
  3. Press Enter.
  4. Click Name to sort files by name.
  5. If file msmsgri32.exe is in the list, delete it.
  6. If file msnetsys32.exe is in the list, delete it.
  7. If file payload.dat is in the list, delete it.
If deleting files fails, use the following steps to verify that payload.dat, msmsgri32.exe, and msnetsys32.exe are not running:
  1. Press CTRL+ALT+DEL once.
  2. Click Task Manager.
  3. Click the Processes tab.
  4. Confirm that payload.dat, msmsgri32.exe, and msnetsys32.exe are not in the list.

Delete the worm registry entries

To delete the worm registry entries
  1. On the Start menu, click Run.
  2. Type regedit and click OK.
  3. In the left pane, navigate to the key:
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, right-click the following values if they exist:
    Mssyslanhelper = <full_worm_path>
    System Initialization = <system folder>\payload.dat
  5. Select Delete and click Yes to delete the values.
  6. Close the Registry Editor.

Restart the computer

To restart the computer
  1. On the Start menu, click Shut Down.
  2. Select Restart from the drop-down list and click OK.

Scan network shares with an antivirus program

  1. On the Start menu, click Run.
  2. Type cmd and click OK.
  3. Type net share
  4. Run an antivirus program to scan the resource locations of listed shares.

Take steps to prevent re-infection

Do not reconnect your computer to the Internet until the computer is protected from re-infection. See the "Preventing Infection" section for more information.
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