Analysis by: Bren Matthew Ebriega
ALIASES:

Trojan:Win32/KryptInject (MICROSOFT); Trojan.Win32.Agent.xaaewi (KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

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

  TECHNICAL DETAILS

File Size: 548,352 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 26 Jul 2019

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:

  • %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe → Normal File
  • %User Temp%\UnI{4 Hex Characters}.bat → Deletes Malwares Original Self.
  • %User Temp%\UnI{4 Hex Characters}.bat → Deletes {AcroRd32.exe or IntelGraphicsController.exe}

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following copies of itself into the affected system:

  • %Program Files%\Intel\Intel(R) Processor Graphics\RasTls.dll

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • %System%\cmd.exe /c takeown /F C:\Program Files\Intel\Intel(R) Processor Graphics\IntelGraph
  • %System%\cmd.exe /c takeown /F C:\Program Files\Intel\Intel(R) Processor Graphics\RasTls.dll
  • %System%\cmd.exe /c icacls %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe /grant administrators:F
  • %System%\cmd.exe /c icacls %Program Files%\Intel\Intel(R) Processor Graphics\RasTls.dll /grant administrators:F
  • %System%\cmd.exe /c icacls %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe /grant users:F
  • %System%\cmd.exe /c icacls %Program Files%\Intel\Intel(R) Processor Graphics\RasTls.dll /grant users:F
  • %System%\dllhost.exe /Processid:{Generated GUID}
  • %System%\cmd.exe /c %User Temp%\UnI{4 Hex Characters}.bat
  • %System%\cmd.exe /c %User Temp%\UnI{4 Hex Characters}.bat
  • %System%\cmd.exe /c rd /s/q %All Users Profile%\Intel\Up\*

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

It injects itself into the following processes running in the affected system's memory:

  • %System%\dllhost.exe /Processid:{Generated GUID}

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %Program Files%\Intel\ → If it does not exist.
  • %Program Files%\Intel\Intel(R) Processor Graphics\

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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

  • abcdefghij1234567890

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
IntelGraphicsController = %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe /Processid:{Generated GUID}

Other System Modifications

This Backdoor deletes the following files:

  • %User Temp%\UnI{4 Hex Characters}.bat
  • %User Temp%\UnI{4 Hex Characters}.bat

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Backdoor Routine

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

  • Manage Files (Copy,Read,Delete,Write)
  • Manage Processes (List Running, Kill)
  • Manage Command Shell (Open, Open as User, Kill, Send Commands to Execute)
  • Get Drive Info (Drive Type, Disk Space)
  • Get Directory Info
  • Get List of Installed Software
  • Run Executable Files
  • Take Screenshot
  • Uninstall and Remove Self
  • Exit Self
  • Update Configuration
  • Send Configuration

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

  • {BLOCKED}.{BLOCKED}.8.255:443

Information Theft

This Backdoor gathers the following data:

  • Computer Name
  • User Name
  • OS Version
  • OS Architecture
  • Local IP Address
  • MAC Address

Other Details

This Backdoor adds the following registry keys:

HKEY_LOCAl_MACHINE\SOFTWARE\Intel\
Java
user = {Encrypted String in Base64}

It does the following:

  • It checks the process name it is running under and will exit if is not equal to the following:
    • winword.exe
    • excel.exe
    • powerpnt.exe
    • eqnedt32.exe
    • acrord32.exe

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 15.266.04
FIRST VSAPI PATTERN DATE: 30 Jul 2019
VSAPI OPR PATTERN File: 15.267.00
VSAPI OPR PATTERN Date: 31 Jul 2019

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • Troj.Win32.TRX.XXPE50FFF039

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

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 4

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • IntelGraphicsController = %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe /Processid:{Generated GUID}

Step 6

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_LOCAl_MACHINE\SOFTWARE\Intel\Java
    • user = {Encrypted String in Base64}

Step 7

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.
  • %Program Files%\Intel\Intel(R) Processor Graphics\

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.PLUGX.DUKSL. 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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