BKDR64_WINNTI.A

 Analysis by: Nikko Tamana

 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. It may be dropped by other malware.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

01 Mar 2013

Payload:

Compromises system security, Connects to URLs/IPs, Collects system information, Drops files

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.

It may be dropped by the following malware:

  • BKDR_WINNTI.A

Installation

This backdoor s DLL component is injected to the following process(es):

  • explorer.exe
  • winlogon.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {2B03B1EF-D379-40C7-9B06-EE1EEA2F151E}

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Enumerate processes and process modules
  • Get system information
    • processor
    • RAM
    • product ID
    • organization
    • host name
    • current user
    • uptime
    • system directory
    • number of processors
    • current display resolution and refresh rate
    • drive information
  • Copy file time from one file to another
  • List users
  • Add user
  • Delete user
  • Change user password
  • Start a process
  • Start a process with a standard input/output redirected to the C&C server
  • Connect to another C&C server
  • Start WinVNC server
  • Enumerate stored user credentials in the LSASS process

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

  • {BLOCKED}t.{BLOCKED}iang.info:53
  • {BLOCKED}t.{BLOCKED}i.info:53
  • {BLOCKED}t.{BLOCKED}g.info:53
  • {BLOCKED}t.{BLOCKED}lk.me:53
  • {BLOCKED}x.{BLOCKED}8.com:53

NOTES:

It injects itself to explorer.exe and winlogon.exe if it is running in rundll32.exe.

  SOLUTION

Minimum Scan Engine:

9.300

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

Remove malware/grayware files that dropped/downloaded BKDR64_WINNTI.A

    • BKDR_WINNTI.A

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR64_WINNTI.A. 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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