Trojan.PS1.FUPORPLEX.AB

June 29, 2021
 Analysis by: Clive Fuentebella
 ALIASES:

Trojan:PowerShell/Splitfuse.C (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.

It requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size:

11,921 bytes

File Type:

PS1

Memory Resident:

Yes

Payload:

Connects to URLs/IPs

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.exe -nop -exec bypass -EncodedCommand {Base64-encoded command}

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

  • Global\bF5UPnqxCnbr

Download Routine

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

  • http://{BLOCKED}f.me/in.php?id=2 (If the sample is not executed in a 64-bit machine)
  • http://{BLOCKED}f.me/in.php?id=3

Other Details

This Trojan requires its main component to successfully perform its intended routine.

It does the following:

  • It connects to the mentioned URL to download the exploits only once the sample is not executed in administrative mode.
  • It uses reflective loading on the downloaded exploits.
  • It uses the vulnerabilities to execute a file passed through a parent sample in an elevated privilege.
  • It uses Tater for privilege escalation.

It takes advantage of the following exploit(s):

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.810.02

FIRST VSAPI PATTERN DATE:

29 Jun 2021

VSAPI OPR PATTERN File:

16.811.00

VSAPI OPR PATTERN Date:

30 Jun 2021

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.FUPORPLEX.AB. 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:

Step 4

Download and apply these security patches Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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