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Backdoor.Linux.WINNTI.F

October 25, 2022
 Analysis by: Jeffrey Francis Bonaobra
 ALIASES:

Backdoor:Linux/Winnti.A!dha (MICROSOFT)

 PLATFORM:

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 executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

416,888 bytes

File Type:

ELF

Memory Resident:

No

Initial Samples Received Date:

05 Aug 2022

Payload:

Connects to URLs/IPs, Steals information

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.

Installation

This Backdoor drops the following files:

  • if 0 is passed as an argument:
    • /var/run/libudev.pid
  • if 1 is passed as an argument:
    • /var/run/libudev.pid
    • /var/run/libudev1.pid

It adds the following processes:

  • HIDE_THIS_SHELL=x /lib/libxselinux 0 &
  • /lib/libxselinux 0
  • /usr/sbin/dmidecode | grep -i 'UUID' |cut -d' ' -f2 2>/dev/null

Backdoor Routine

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

  • Execute arbitrary commands

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

  • {BLOCKED}.{BLOCKED}.124.53:53
  • https://{BLOCKED}.{BLOCKED}.124.53

However, as of this writing, the said sites are inaccessible.

Information Theft

This Backdoor gathers the following data:

  • UUID

Other Details

This Backdoor requires the existence of the following files to properly run:

  • /lib/libxselinux.so

It does the following:

  • It requires being executed in the following directory:
    • /lib

It accepts the following parameters:

  • 0
  • 1

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.894.04

FIRST VSAPI PATTERN DATE:

24 Oct 2022

VSAPI OPR PATTERN File:

17.895.00

VSAPI OPR PATTERN Date:

25 Oct 2022

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.ELF.TRX.XXELFC1DFF020

Step 2

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Linux.WINNTI.F. 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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