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Backdoor.MSIL.WEBSHELL.SMRAH

February 07, 2023
 Analysis by: Jeffrey Francis Bonaobra
 ALIASES:

Trj/GdSda.A (PANDA)

 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

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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 takes advantage of certain vulnerabilities. It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  TECHNICAL DETAILS

File Size:

8,704 bytes

File Type:

DLL

Memory Resident:

No

Initial Samples Received Date:

01 Feb 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.

Backdoor Routine

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

  • Execute arbitrary commands via cmd.exe

Other Details

This Backdoor does the following:

  • It can send commands to a pipe named:
    • splsvc
  • It requires a powershell script to register itself with IIS.

It takes advantage of the following vulnerabilities:

It requires being hosted on a web server in order to proceed with its intended routine.

It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.104.08

FIRST VSAPI PATTERN DATE:

01 Oct 2021

VSAPI OPR PATTERN File:

17.105.00

VSAPI OPR PATTERN Date:

02 Oct 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

Scan your computer with your Trend Micro product to delete files detected as Backdoor.MSIL.WEBSHELL.SMRAH. 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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