Analysis by: Jeffrey Francis Bonaobra
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 1,353 bytes
File Type: PS1
Memory Resident: No
Initial Samples Received Date: 02 Jan 2023
Payload: Modifies system registry, Bypasses AMSI

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 adds the following processes:

  • powershell -nop -w hidden -encodedcommand {Base64 encoded command}
  • PowerShell.exe -WindowStyle hidden -encodedCommand {Base64 encoded command}

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}.{BLOCKED}.61.182/load/uac

As of this writing, the said sites are inaccessible.

Other Details

This Trojan does the following:

  • It bypasses Antimalware Scan Interface (AMSI).

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.170.05
FIRST VSAPI PATTERN DATE: 02 Jan 2023
VSAPI OPR PATTERN File: 18.171.00
VSAPI OPR PATTERN Date: 03 Jan 2023

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

Scan your computer with your Trend Micro product to delete files detected as Trojan.PS1.KILLAV.AL. 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:


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