Analysis by: Paolo Ronniel Labrador
ALIASES:

Backdoor:PowerShell/Obfuse!MSR (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

This Trojan 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: 16,282 bytes
File Type: PS1
Memory Resident: No
Initial Samples Received Date: 19 Oct 2022
Payload: Connects to URLs/IPs, Drops files

Arrival Details

This Trojan 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 drops the following files:

  • %AppDataLocal%\Microsoft\Windows\Update\ID.txt (contains information from CNC Server)
  • %AppDataLocal%\Microsoft\Windows\Update\c.txt (contains information decryptor block)
  • {path indicated by CNC Server}\{file name indicated by the CNC Server}

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

Other Details

This Trojan does the following:

  • It downloads string content from:
    • http://{BLOCKED}.{BLOCKED}.{BLOCKED}.189/get
      • And saves the string to the following file:
        • %AppDataLocal%\Microsoft\Windows\Update\ID.txt
  • It uploads information encryptor block to:
    • http://{BLOCKED}.{BLOCKED}.{BLOCKED}.189/get
  • It will try execute the following file:
    • %AppDataLocal%\Microsoft\Windows\Update\temp.ps1 (possible downloaded file)

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.514.02
FIRST VSAPI PATTERN DATE: 07 Aug 2024
VSAPI OPR PATTERN File: 19.515.00
VSAPI OPR PATTERN Date: 08 Aug 2024

Step 1

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 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

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.  
  • %AppDataLocal%\Microsoft\Windows\Update\ID.txt
  • %AppDataLocal%\Microsoft\Windows\Update\c.txt
  • {path indicated by CNC Server}\{file name indicated by the CNC Server}
  • %AppDataLocal%\Microsoft\Windows\Update\temp.ps1

Step 4

Scan your computer with your Trend Micro product to delete files detected as Trojan.PS1.DLOADR.B. 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 the following Trend Micro Support pages for more information:


Did this description help? Tell us how we did.