Description: 

This backdoor is usually dropped by TROJ_MULDROP.Q. It drops its nonmalicious component files on an affected system and creates registry entries to enable its dropped files to run every time Windows restarts.

This backdoor logs all user keystrokes. It also opens an Internet Explorer in the background, using a random port, thus allowing a remote user to gain access to the infected system.

Details:

Arrival and Installation

This backdoor program is dropped by TROJ_MULDROP.Q.

Upon execution, it drops a copy of itself in the Windows folder as WIN32.EXE. It may also drop the following nonmalicious components:

• Win32_hook.dll a tool from madcodehook
• Win32.dll a tool from madcodehook
• Win32key.dll a dll file that hooks the keyboard presses

Autostart Technique

On Win 95, 98, and ME, this backdoor creates the following registry entry to enable its dropped file to run at every startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
Win32.exe = %Windows%\Win32.exe

(Note: %Windows% is the default Windows folder, usually C:\Windows or C:\WINNT.)

On NT-based systems, this backdoor creates the following registry keys to register itself as service:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\mchInjDrv

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\win32

Backdoor Routines

This backdoor has the ability to log all user keystrokes. It also opens an Internet Explorer in the background, using a random port, which allows a remote user to gain access to the infected system.

Other Details

This backdoor creates the following mutex to prevent multiple copies of itself running on the system:

Gpigeon5_SHARED_MUTEX

It also has rootkit functionalities, which allows it to hide its process and dropped files.

Analysis By: Dexter See To

Revision History:

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:

Note: Refer to the Clean Solution for TROJ_MULDROP.Q.

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.

On Windows Server 2003

1. Restart your computer.
2. When are prompted to select the operating system to start, press F8.
3. On the Windows Advanced Option menu, use the arrow keys to select Safe Mode, and then press Enter.

Note: After performing all the solutions for the removal of this malware, please restart your system normally, and run your Trend Micro antivirus product.

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_CURRENT_USER>Software>Microsoft>
   Windows>CurrentVersion>Run
3. In the right panel, locate and delete the entry, if it exists:
   Win32.exe = %Windows%\Win32.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 95, 98 and ME, C:\WINNT\System32 on Windows NT and 2000, and C:\Windows\System32 on Windows XP.)
4. In the left panel, double-click the following:
   HKEY_LOCAL_MACHINE>System>
   CurrentControlSet>Services>
5. Still in the left panel, right-click on the following key, if it exists, and choose Delete:
   mchInjDrv
6. In the left panel, double-click the following:
   HKEY_LOCAL_MACHINE>System>
   CurrentControlSet>Services
7. Still in the left panel, right-click on the following key, if it exists, and choose Delete:
   win32
8. Close Registry Editor.

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:
   Win32_hook.dll
   Win32.dll
   Win32key.dll
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 sets.

Scan your system with Trend Micro antivirus and delete files detected as BKDR_AWQ.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.

Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.