Analysis by: Maria Emreen Viray
ALIASES:

Trojan.Win32.Agentb.jkqp (KASPERSKY); Trojan:Win32/Aptdrop.H (MICROSOFT)

 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

Infection Channel: 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 executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 547,840 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 24 Jan 2021
Payload: Connects to URLs/IPs, Steals information

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:

  • %User Temp%\UnI{4 Hex Characters}.bat → deletes the module that ran the DLL, and deletes itself
  • %User Temp%\UnI{4 Hex Characters}.bat → deletes the malicious DLL, and then itself
  • %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe → originally dropped as %User Temp%\{Random 7 digits}.tmp

(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).. %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 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 "%Program Files%\Intel\Intel(R) Processor Graphics\RasTls.dll""
  • %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\RasTls.dll" /grant users:F"
  • %System%\cmd.exe /c "takeown /F "%Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe""
  • %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\IntelGraphicsController.exe" /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 "%ProgramData%\Windows\Intel\Up\*""

(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).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

It creates the following folders:

  • %Program Files%\Intel
  • %Program Files%\Intel\Intel(R) Processor Graphics
  • %ProgramData%\Windows\Intel
  • %ProgramData%\Windows\Intel\Up

(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).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

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

  • abcdefghij1234567890

It injects codes into the following process(es):

  • %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.)

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 adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Intel\
Java
user = {Encrypted String}

Backdoor Routine

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

  • Execute Shell Commands
  • Folder and File Manipulation (Create, Copy, Delete, Read, Write)
  • Get Drive Information
  • Get list of installed software
  • List Software Installed
  • Manage Processes (list running processes and their details; kill processes)
  • Run executable files
  • Take Screenshots
  • Terminate Self
  • Terminate connection with C&C
  • Uninstall self from machine (removes self and autostart configurations)
  • Updates configuration (stored in .cotx section and registry)

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

  • {BLOCKED}.{BLOCKED}.1.187:443
  • {BLOCKED}.{BLOCKED}.111.111:443
  • www3.{BLOCKED}lass.com:443

Information Theft

This Backdoor gathers the following data:

  • Computer Name
  • Domain
  • Local IP addresses
  • MAC Address
  • OS Version
  • Username

Other Details

This Backdoor does the following:

  • uses takeown.exe to make dropped malicious files owned by administrator
  • uses icalcs.exe to grant full access for administators and logon user to malicious files
  • uses a legitimate binary (dropped by file itself [IntelGraphicsController.exe]) to run the malicious DLL (RasTls.dll)
  • stores encrypted C&C configuration in the .cotx section of the file and HKEY_LOCAL_MACHINE\SOFTWARE\Intel\Java key

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.446.08
FIRST VSAPI PATTERN DATE: 30 Dec 2020
VSAPI OPR PATTERN File: 16.447.00
VSAPI OPR PATTERN Date: 31 Dec 2020

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.XXPE50FFF040

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}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Intel\Java
    • user = {Encrypted String}

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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Intel\Java

Step 7

Search and delete these files

[ 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.
  • %Program Files%\Intel\Intel(R) Processor Graphics\RasTls.dll
  • %Program Files%\Intel\Intel(R) Processor Graphics\IntelGraphicsController.exe
  • %User Temp%\UnI{4 Hex Characters}.bat
  • %User Temp%\UnI{4 Hex Characters}.bat

Step 8

Search and delete this folder

[ 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
  • %Program Files%\Intel\Intel(R) Processor Graphics
  • %ProgramData%\Windows\Intel
  • %ProgramData%\Windows\Intel\Up

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.COTX.SMYPAL-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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