WORM_RAHACK.A

Malware type: Worm

Aliases: Worm.Win32.Rahak.a (Kaspersky), W32/RAHack (McAfee), W32.Rahack (Symantec), BDS/Agent.GO (Avira), W32/RAHack-I (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Description: 

This memory-resident worm drops the following files in the Windows system folder:

  • MSCOLSRV.EXE - copy of itself
  • SVCHSOT.EXE - copy of itself
  • SERVER.DLL
  • SYSHID.EXE

It also drops the file SYSTEM.VBS in the Windows startup folder.

This worm searches for IP addresses and attempts to access these systems using the Radmin program (Radmin is a program that enables users to control on one or more computers). It then drops and executes a copy of itself as SRVSXC.EXE in the target system.

This worm also searched for .HTM and .HTML files in a target system. It then drops copies of itself using the same file name as the .HTML and .HTM files, but with an .EXE extension.

This worm runs on Windows 95, 98, ME, NT, 2000, and XP.

For additional information about this threat, see:

Description created: Jan. 17, 2005 5:53:55 PM GMT -0800


TECHNICAL DETAILS


Size of malware: 69,565 Bytes

Initial samples received on: Jan 17, 2005

Details:

This memory-resident worm drops the following files in the Windows system folder:

  • MSCOLSRV.EXE - copy of itself
  • SVCHSOT.EXE - copy of itself
  • SERVER.DLL
  • SYSHID.EXE

It also drops the file SYSTEM.VBS in the Windows startup folder.

To ensure its automatic execution at every Windows startup, it creates the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
Sysser = <worm file name>

To run itself as service, it creates the following registry entry:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\RunServices
MSCoolServ = <worm file name>

It also creates a new service name MSCoolServ, which executes automatically, by creating the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSCoolServ

It also creates the following registry entries:

HKEY_CLASSES_ROOT\CLSID\{902F739F-9F1F-A8A2-4860-97D74B599D6A}

HKEY_LOCAL_MACHINE\Software\CLASSES\CLSID\
{902F739F-9F1F-A8A2-4860-97D74B599D6A}

HKEY_LOCAL_MACHINE\Software\Radmin

Registry Shell Spawning

This worm also modifies the following registry entry so that it executes every time files with .EXE extension are run:

HKEY_CLASSES_ROOT\exefile\shell\open\command
(default) = ""%1" %*" "syshid.exe "%1" %*""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile\shell\open\command
(default) = ""%1" %*" "syshid.exe "%1" %*""

Network Propagation

This worm searches for IP addresses and attempts to access these systems using the Radmin program (Radmin is a program that enables users to control on one or more computers).

It creates the text file LOGX.TXT in the same folder wherw this worm is executed. This file contains the gathered IP addresses. It the uses the following hardcoded list of weak passwords to gain access to target systems:

  • 123456789
  • 11111111
  • 12345678
  • password
  • qwertyui
  • 00000000
  • 12341234

It then drops and executes a copy of itself as SRVSXC.EXE in the target system.

This worm also searched for .HTM and .HTML files in a target system. It then drops copies of itself using the same file name as the .HTML and .HTM files, but with an .EXE extension.

Other Details

This FSG-compressed worm is written and compiled using Visual C%20%20.




Analysis by: Mylene Enriquez

Revision History:

First pattern file version: 5.540.03
First pattern file release date: Sep 12, 2008

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 5.541.00

Pattern release date: Sep 14, 2008


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

Restarting in Safe Mode

� On Windows 95

  1. Restart your computer.
  2. Press F8 at the Starting Windows 95 message.
  3. Choose Safe Mode from the Windows 95 Startup Menu then press Enter.

� On Windows 98 and ME

  1. Restart your computer.
  2. Press the CTRL key until the startup menu appears.
  3. Choose the Safe Mode option then press Enter.

� On Windows NT (VGA mode)

  1. Click Start>Settings>Control Panel.
  2. Double-click the System icon.
  3. Click the Startup/Shutdown tab.
  4. Set the Show List field to 10 seconds and click OK to save this change.
  5. Shut down and restart your computer.
  6. Select VGA mode from the startup menu.

� On Windows 2000

  1. Restart your computer.
  2. Press the F8 key, when you see the Starting Windows bar at the bottom of the screen.
  3. Choose the Safe Mode option from the Windows Advanced Options Menu then press Enter.

� On Windows XP

  1. Restart your computer.
  2. Press F8 after the Power-On Self Test (POST) is done. If the Windows Advanced Options Menu does not appear, try restarting and then pressing F8 several times after the POST screen.
  3. Choose the Safe Mode option from the Windows Advanced Options Menu then press Enter.

Addressing Registry Shell Spawning

This procedure prevents the malware from executing whenever a user opens files with certain extension names. It should restore the registry to its original settings.

  1. Click Start>Run.
  2. In the Open input box, type:
    command /c copy %WinDir%\regedit.exe regedit.com | regedit.com
  3. Press Enter.
  4. In the left panel, double-click the following:
    HKEY_CLASSES_ROOT>exefile>shell>open>command
  5. In the right panel, locate the registry entry:
    Default
  6. Check whether its value is the path and file name of the malware file.
  7. If the value is the malware file, right-click Default and select Modify to change its value.
  8. In the Value data input box, delete the existing value and type the default value:
    "%1"%*
  9. Repeat this procedure for the following registry key:
    HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile\shell\open\command
  10. Close Registry Editor.
  11. Click Start>Run, then type:
    command /c del regedit.com
  12. Press Enter.

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing at startup.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    Sysser = <worm file name>
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>RunServices
  5. In the right panel, locate and delete the entry:
    MSCoolServ = <worm file name>

NOTE: If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Removing Malware Entries from the Registry

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_CLASSES_ROOT>CLSID
  2. Still in the left panel, locate and delete the key:
    {902F739F-9F1F-A8A2-4860-97D74B599D6A}
  3. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Classes>CLSID
  4. Still in the left panel, locate and delete the key:
    {902F739F-9F1F-A8A2-4860-97D74B599D6A}
  5. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SYSTEM
  6. Still in the left panel, locate and delete the key:
    Radmin
  7. Close Registry Editor.

Disabling Malware Service

This stops the running malware service on systems running Windows NT, 2000, and XP.

  1. Open a command prompt window. Click Start>Run, type CMD, and then press the Enter.
  2. At the command prompt, type the following:
    NET STOP �MSCoolServ�
  3. Press Enter. A message should indicate that the service has been stopped successfully.
  4. Close the command prompt window.

Deleting Malware File

  1. Right-click Start then click Search� or Find�, depending on the version of Windows you are running.
  2. In the Named input box, type:
    logX.txt
  3. In the Look In drop-down list, select the drive that contains Windows, then press Enter.
  4. Once located, select the file then press Delete.

Additional Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected systems.

Users running other Windows versions can proceed with the succeeding procedure set(s).

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and delete all files detected as WORM_RAHACK.A. To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro�s online virus scanner.




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