TROJ_CAGER.A

Malware type: Trojan

Aliases: Generic BackDoor.k (McAfee), Trojan Horse (Symantec), TR/VB.ZU.1 (Avira), Mal/VB-F (Sophos),

In the wild: Yes

Destructive: No

Language: Arabic, English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Low

Distribution potential:

Low

Description: 

This memory-resident Trojan may be downloaded from the Internet, dropped by another malware, or manually installed by a user.

It adds several registry entries to enable its automatic execution at Windows startup. This autostart technique fails, however, since the said registry entries point to a non-existent file.

This Trojan displays a series of images when the Internet Explorer browser title bar contains any of the following text strings:

  • Exhibitionism
  • jeggar
  • Penis
  • Phallic
  • Phallus
  • Priapus
  • sex
  • teen

Based on the cited text strings, it appears that this Trojan aims to disrupt browsing activities related to adult or mature materials. This interference may cause annoyance to some users. The proceeding text further illustrates this Trojan's routine.

If the said strings are found, this Trojan minimizes the Internet Explorer (IE) window and displays the following image:

After a few seconds or if the Next button is clicked, this Trojan proceeds to display the following image in the center of the screen:

The said image disappears after a few seconds.

If the minimized window is restored, or another window containing the aforementioned strings is opened, this Trojan again displays two images in succession.

If another IE window containing the said strings is opened and the second cited image has been displayed six (6) times, the following image is shown together with the current time:

If the mouse cursor is moved within the shown gray area, the following image appears and "traps" the mouse cursor:

Clicking any of the buttons shown in the screen logs off the user from Windows.

Additionally if Registry Editor is opened, it is minimized by this Trojan.

For additional information about this threat, see:

Description created: Sep. 6, 2005 3:06:06 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 17,232 Bytes

Initial samples received on: Sep 6, 2005

Payload 1: Displays a series of images

Payload 2: Logs off user from Windows

Details:

Installation and Autostart

This memory-resident Trojan may be downloaded from the Internet, dropped by another malware, or manually installed by a user.

Upon execution, it adds the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
LoadService = "Virus"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
RavTimeXP = "Virus"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
System4224411 = "Virus"

This autostart technique fails, however, since the said registry entries point to a non-existent file.

Payload

Based on the cited text strings, it appears that this Trojan aims to disrupt browsing activities related to adult or mature materials. This interference may cause annoyance to some users. The proceeding text further illustrates this Trojan's routine.

If the said strings are found, this Trojan minimizes the Internet Explorer (IE) window and displays the following image:

After a few seconds or if the Next button is clicked, this Trojan proceeds to display the following image in the center of the screen:

The said image disappears after a few seconds.

If the minimized window is restored, or another window containing the aforementioned strings is opened, this Trojan again displays two images in succession.

If another IE window containing the said strings is opened and the second cited image has been displayed six (6) times, the following image is shown together with the current time:

If the mouse cursor is moved within the shown gray area, the following image appears and "traps" the mouse cursor:

Clicking any of the buttons shown in the screen logs off the user from Windows.

Additionally if Registry Editor is opened, it is minimized by this Trojan.

Other Details

This Trojan is compiled using Microsoft Visual Basic. It runs on Windows 98, ME, NT, 2000, and XP.

Analysis By: Zeus M. Laguerta


SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.822.06

Pattern release date: Sep 6, 2005


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:

Identifying the Malware Program

To remove this malware, first identify the malware program.

  1. Scan your system with your Trend Micro antivirus product.
  2. NOTE the path and file name of all files detected as TROJ_CAGER.A.

Trend Micro customers need to download the latest virus pattern file before scanning their system. Other users can use Housecall, Trend Micro's online virus scanner.

Terminating the Malware Program

This procedure terminates the running malware process. You will need the name(s) of the file(s) detected earlier.

If the process you are looking for is not in the list displayed by Task Manager, proceed to the succeeding solution set.

  1. Open Windows Task Manager.
    • On Windows 98 and ME, press
    CTRL%20ALT%20DELETE
    • On Windows NT, 2000, and XP, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. Close Task Manager.

*NOTE: On systems running Windows 98 and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions. If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Editing the Registry

This malware modifies the system's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. HOW TO: Backup, Edit, and Restore the Registry in Windows 95, Windows 98, and Windows ME
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and 2003

Removing Autostart Entries from the Registry

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

If the registry entries below are not found, the malware may not have executed as of detection. If so, proceed to the succeeding solution set.

  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 entries:
    • LoadService = "Virus"
    • RavTimeXP = "Virus"
    • System4224411 = "Virus"
  4. Close Registry Editor.

Important 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 files detected as TROJ_CAGER.A. To do this, Trend Micro customers must download the latest virus pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro's online virus scanner.




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