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Trojan.SH.MIRAI.BOI

July 23, 2020
 Analysis by: Jemimah Mae Molina
 ALIASES:

BV:Downloader-JS [Drp] (AVAST); Linux/Downloader.p(NAI)

 PLATFORM:

Unix

 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.

  TECHNICAL DETAILS

File Size:

2,700 bytes

File Type:

Script

Memory Resident:

No

Initial Samples Received Date:

22 Jul 2020

Payload:

Connects to URLs/IPs, Downloads files

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.

Download Routine

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

  • http://{BLOCKED}.{BLOCKED}.8.24/bins/sora.{architecture}
    where {architecture} are the following:
    • x86
    • mips
    • mpsl
    • arm4
    • arm5
    • arm6
    • arm7
    • ppc
    • m68k
    • sh4

It saves the files it downloads using the following names:

  • {directory}/sysctl
    where {directory} can be any of the following:
    • /tmp
    • /var/run
    • /mnt
    • /root
    • /etc/init.d
    • / (root directory)

Other Details

This Trojan does the following:

  • It switches to root user to have root privileges.
  • It clears the following objects:
    • /etc/cron.d/start
    • /etc/cron.daily/dkpp
  • It creates the following cron job to enable automatic execution of $PATH:/var/run/sysctl:
    • Paths:
      • /etc/cron.d/start
      • /etc/cron.daily/dkpp
      Schedule: At 00:00
      Command: 00 00 * * * root PATH="$PATH:/var/run/sysctl"
  • It resets the IP policy table.
  • It blocks incoming TCP connections on the following ports:
    • 22
    • 23
    • 80
    • 443
    • 8080
    • 9000
    • 8089
    • 7070
    • 8081
    • 9090
    • 161

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

16.118.05

FIRST VSAPI PATTERN DATE:

22 Jul 2020

VSAPI OPR PATTERN File:

16.119.00

VSAPI OPR PATTERN Date:

23 Jul 2020

Scan your computer with your Trend Micro product to delete files detected as Trojan.SH.MIRAI.BOI. 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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