Analysis by: Janus Agcaoili
ALIASES:

HEUR:Backdoor.PHP.WebShell.gen (Kaspersky)

 PLATFORM:

Windows, Linux

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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 may be hosted on a website and run when a user accesses the said website.

  TECHNICAL DETAILS

File Size: 10010 bytes
File Type: PHP
Memory Resident: No
Initial Samples Received Date: 15 Jul 2022
Payload: Displays message/message boxes

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.

It may be hosted on a website and run when a user accesses the said website.

Other Details

This Backdoor does the following:

  • Displays the following when successfully hosted on a victim server and accessed:
  • Allows arbitrary upload of files on the affected server using the provided UI
  • The UI provides the following actions/commands for each of the file displayed:
    • Delete
    • Edit
    • Rename
    • Chmod
  • Displays the current directory and files within the same directory where this file is hosted

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 17.694.05
FIRST VSAPI PATTERN DATE: 18 Jul 2022
VSAPI OPR PATTERN File: 17.695.00
VSAPI OPR PATTERN Date: 19 Jul 2022

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.PHP.WEBSHELL.SBJSRMTYX. 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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