Analysis by: Marfel Tiamzon

 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 366,143 b bytes
Memory Resident: Yes

Installation

This backdoor drops the following copies of itself into the affected system:

  • %System%\nvctrl.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

  • %Windows%\LightSaver

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
@@ = %system%\nvctrl.exe

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Control Panel\Desktop
SCRNSAVE.EXE = %system%\KimmoSE.scr

It modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
ScreenSaveTimeOut = 30

(Note: The default value data of the said registry entry is 600.)

HKEY_CURRENT_USER\Control Panel\Desktop
ScreenSaveActive = 1

(Note: The default value data of the said registry entry is 0.)

  SOLUTION

Minimum Scan Engine: 8.900

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and terminate files detected as BKDR_AGENT.EUM

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • @@=%system%\nvctrl.exe

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • SCRNSAVE.EXE=%system%\KimmoSE.scr

Step 5

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • From: ScreenSaveTimeOut=30
      To: ScreenSaveTimeOut=600


  • In HKEY_CURRENT_USER\\Control Panel\\Desktop
    • From: ScreenSaveActive=1
      To: ScreenSaveActive=0

Step 6

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.

  • %Windows%\LightSaver\KimmoSE.ini

  • %System%\KimmoSE.scr

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_AGENT.EUM. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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