Backdoor.PS1.SYSTEMBC.A

August 10, 2023
 Analysis by: Arianne Grace Dela Cruz
 ALIASES:

PowerShell/Agent.HP trojan (NOD32); PS1.Loader.45734 (QUICKHEAL)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • 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.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

8,669 bytes

File Type:

PS1

Memory Resident:

No

Initial Samples Received Date:

09 Aug 2023

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.

Autostart Technique

This Backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
socks = Powershell.exe -windowstyle hidden -ExecutionPolicy Bypass -File {Malware File Name}

Backdoor Routine

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

  • Execute arbitrary command

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

  • 5.{BLOCKED}.37:4001

Information Theft

This Backdoor gathers the following information on the affected computer:

  • OS Version

Other Details

This Backdoor does the following:

  • It uninstalls the autorun registry created before terminating itself.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.624.03

FIRST VSAPI PATTERN DATE:

09 Aug 2023

VSAPI OPR PATTERN File:

18.625.00

VSAPI OPR PATTERN Date:

10 Aug 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

Identify and terminate files detected as Backdoor.PS1.SYSTEMBC.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • socks = Powershell.exe -windowstyle hidden -ExecutionPolicy Bypass -File {Malware File Name}

Step 5

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


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