Analysis by: Rhena Inocencio

ALIASES:

Backdoor.Darkmoon (Symantec), BackDoor-DKI.gen.da (Mcafee), Win32/Poison.NKN trojan (ESET)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

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 does not have any propagation routine.

It opens a hidden Internet Explorer window. It executes commands from a remote malicious user, effectively compromising the affected system.

It does not drop any other file.

It does not have any downloading capability.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

Ports: TCP Port 443
File Size: 61,452 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Jul 2012
Payload: Connects to URLs/IPs, Opens Internet Explorer window

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

  • fd5gh55a5

It injects threads into the following normal process(es):

  • iexplorer.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
Microsoft netstatupdate = "{malware path and file name}"

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

This backdoor opens a hidden Internet Explorer window.

It executes the following commands from a remote malicious user:

  • Capture screen, audio, and webcam
  • Execute binary instructions
  • Log keystrokes
  • List active ports
  • Manage open windows
  • Manage passwords
  • Manage registry, processes, services, devices, and installed applications
  • Perform multiple simultaneous transfers
  • Perform remote shell
  • Relay server
  • Search files
  • Share servers
  • Update, restart, or terminate itself

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

  • {BLOCKED}0719.6600.org:443

Dropping Routine

This backdoor does not drop any other file.

Download Routine

This backdoor does not have any downloading capability.

Information Theft

This backdoor does not have any information-stealing capability.

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • go.microsoft.com/fwlink/?LinkId={number}

NOTES:

This backdoor does not have rootkit capabilities.

This backdoor does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.282.05
FIRST VSAPI PATTERN DATE: 24 Jul 2012
VSAPI OPR PATTERN File: 9.283.00
VSAPI OPR PATTERN Date: 25 Jul 2012

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

Scan your computer with your Trend Micro product and note files detected as BKDR_POISON.SMJ

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • Microsoft netstatupdate = "{malware path and file name}"

Step 5

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