Analysis by: Alvin Bacani
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 114,744 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Jun 2013
Payload: Compromises system security

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following files:

  • %WINDOWS%\Microsoft.db\res.db - (if Current User is "system")
  • %Windows\ntshrui.dll - detected as BKDR_INJECT.PRM (if Current User is not "system").
  • %\WINDOWS%\system32\mecmshare.dat - detected as BKDR_INJECT.PRM
  • %WINDOWS%\Microsoft.db\dbServer.exe - detected as BKDR_INJECT.PRM (if Current User is "system")

It creates the following folders:

  • %WINDOWS%\Microsoft.db - (if the current user is "system")

It injects codes into the following process(es):

  • explorer.exe
  • userinit.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
MicrosoftDb = "%WINDOWS%"\Microsoft.db\dbServer.exe - (if the Current User is "system")

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}g.{BLOCKED}6.info via port 8080

As of this writing, the said servers are currently inaccessible.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.102.03
FIRST VSAPI PATTERN DATE: 19 Jun 2013
VSAPI OPR PATTERN File: 10.103.00
VSAPI OPR PATTERN Date: 19 Jun 2013

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

Restart in Safe Mode

[ Learn More ]

Step 3

Search and delete this file

[ 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%\ntshrui.dll
  • %System%\memshare.dat
  • %Windows\Microsoft.db\dbserver.exe
  • %Windows\Microsoft.db\res.db

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • MicrosoftDb = "%WINDOWS%"\Microsoft.db\dbServer.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_INJECT.PRM. 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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