Analysis by: Marcus Ma. Antonio Capistrano

ALIASES:

Trojan.Win32.Agentb.ixmh (KASPERSKY), a variant of Win32/GenKryptik.BQUG trojan (NOD32),W32/GenKryptik.BQUG!tr (FORTINET)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 1,296,384 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Feb 2018

Arrival Details

This Trojan Spy 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 Trojan Spy drops a copy of itself in the following folders using different file names:

  • %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

(Note: %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 Trojan Spy modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random 8 character string} = %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

Other System Modifications

This Trojan Spy adds the following registry keys:

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
{random values} = {random values}

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
{random values} = {random values}

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
Client = {random values}

Other Details

This Trojan Spy connects to the following possibly malicious URL:

  • {BLOCKED}h.{BLOCKED}o-graph.com/favicon.ico

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.980.04
FIRST VSAPI PATTERN DATE: 21 Feb 2018
VSAPI OPR PATTERN File: 13.981.00
VSAPI OPR PATTERN Date: 22 Feb 2018

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 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.

 
  • In HKEY_CURRENT_USER\Software\AppDataLow\Software\Microsoft
    • {GUID}

Step 5

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\Microsoft\Windows\CurrentVersion\Run
    • {random 8 character string} = %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

Step 6

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.
  • %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

Step 7

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