Analysis by: Pearl Charlaine Espejo
ALIASES:

Backdoor.LuminosityLink (Malwarebytes)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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: 825,408 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 Sep 2016

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 copies of itself into the affected system:

  • %ProgramData%\Client\client.exe
  • %All Users Profile%\Client\client.exe
  • %Application Data%\clientmonitor.exe

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %ProgramData%\Client
  • %ProgramData%\Client Monitor
  • %All Users Profile%\Client
  • %All Users Profile%\Client Monitor
  • %Application Data%\Monitor
  • %Application Data%\Monitor\Files
  • %Application Data%\Monitor\Guard
  • %Application Data%\Monitor\Logs

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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
Client Monitor = ""%ProgramData%\Client\client.exe" -a /a"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
shell = "explorer.exe,"%Application Data%\clientmonitor.exe""

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software
MTX = "d9bfef661f31a23d3b8f744ce120f39c6c94bace898534a6ae66d5e0c31710e0"

HKEY_CURRENT_USER\Software
PRC = "{Malware Process ID}"

HKEY_CURRENT_USER\Software
PTH = "%ProgramData%\Client\client.exe"

HKEY_CURRENT_USER\Software
SOKZW3n5SX+kzfC7kBs1bw== = "uBmpERdWPP/j7tEX8BhybEKGvW7rOmBq0L3Rn40d4+E="

HKEY_CURRENT_USER\Software
3qPZtpJLHC2OYYxIFgLQIw== = "HTNgKsjZdTpVanJFoLUISz5TBrZPq9tkqMZUy9kBL2Y="

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.131.191:6705

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.310.04
FIRST VSAPI PATTERN DATE: 31 Mar 2017
VSAPI OPR PATTERN File: 13.311.00
VSAPI OPR PATTERN Date: 01 Apr 2017

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

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_CURRENT_USER\Software
    • 3qPZtpJLHC2OYYxIFgLQIw = = = "HTNgKsjZdTpVanJFoLUISz5TBrZPq9tkqMZUy9kBL2Y="
  • In HKEY_CURRENT_USER\Software
    • SOKZW3n5SX+kzfC7kBs1bw = = = "uBmpERdWPP/j7tEX8BhybEKGvW7rOmBq0L3Rn40d4+E="
  • In HKEY_CURRENT_USER\Software
    • PTH = "%ProgramData%\Client\client.exe"
  • In HKEY_CURRENT_USER\Software
    • MTX = "d9bfef661f31a23d3b8f744ce120f39c6c94bace898534a6ae66d5e0c31710e0"
  • In HKEY_CURRENT_USER\Software
    • PRC = "{Malware Process ID}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • Client Monitor = ""%ProgramData%\Client\client.exe" -a /a"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • shell = "explorer.exe,"%Application Data%\clientmonitor.exe""

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %ProgramData%\Client
  • %ProgramData%\Client Monitor
  • %All Users Profile%\Client
  • %All Users Profile%\Client Monitor
  • %Application Data%\Monitor

Step 6

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