Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor may be downloaded by other malware/grayware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size: 49,152 bytes
Memory Resident: Yes
Initial Samples Received Date: 01 Sep 2011

Arrival Details

This backdoor may be downloaded by the following malware/grayware from remote sites:

  • WORM_SMALL.ECD

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This backdoor drops the following files:

  • %Windows%\{number}_Ss.dll - also detected as BKDR_VENIK.AE

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

Other System Modifications

This backdoor modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = "{default value} netsvcs_0x0"

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

It creates the following service using its DLL component:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent\Parameters
ServiceDll = "%Windows%\4_Ss.dll"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent
DisplayName = "netsvcs_0x0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent
ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\apagent
Type = "20"

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.394.15
FIRST VSAPI PATTERN DATE: 02 Sep 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove the malware/grayware file that dropped/downloaded BKDR_VENIK.AE

Step 3

Restart in Safe Mode, and then delete this registry key

[ 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.

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
    • apagent

Step 4

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = "{default value} netsvcs_0x0"
      To: netsvcs = "{default value}"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_VENIK.AE. 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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