Analysis by: Paul Steven Nadera
ALIASES:

Linux/IRCBot.AU trojan (NOD32); HEUR:Backdoor.Linux.Agent.bc (Kaspersky); Trojan:Win32/Ircbrute (Microsoft)

 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.

  TECHNICAL DETAILS

File Size: 4,746 bytes
File Type: , Script
Memory Resident: Yes
Initial Samples Received Date: 23 Aug 2017
Payload: Drops files, Connects to URLs/IPs, Scans for open ports

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 and executes the following files:

  • /opt/{random characters} -> a copy it drops if the script is not running as root

It creates the following folders:

  • /root/.ssh

Other System Modifications

This Backdoor deletes the following files:

  • /root/.bashrc
  • /home/pi/.bashrc
  • /tmp/ktx*
  • /tmp/cpuminer-multi
  • /var/tmp/kaiten

Backdoor Routine

This Backdoor connects to any of the following IRC server(s):

  • ix1.{BLOCKED}et.org
  • ix2.{BLOCKED}et.org
  • Ashburn.Va.Us.{BLOCKED}et.org
  • Bucharest.RO.EU.{BLOCKED}et.Org
  • Budapest.HU.EU.{BLOCKED}et.org
  • Chicago.IL.US.{BLOCKED}et.org

Process Termination

This Backdoor terminates the following processes if found running in the affected system's memory:

  • bins.sh
  • minerd
  • node
  • nodejs
  • ktx-armv4l
  • ktx-i586
  • ktx-m68k
  • ktx-mips
  • ktx-mipsel
  • ktx-powerpc
  • ktx-sh4
  • ktx-sparc
  • arm5
  • zmap
  • kaiten
  • perl

HOSTS File Modification

This Backdoor adds the following strings to the Windows HOSTS file:

  • {BLOCKED}.{BLOCKED}.0.1 bins.deutschland-{BLOCKED}g.eu

Other Details

This Backdoor does the following:

  • Executes the following commands to download libraries needed:
    • apt-get update -y --force-yes
    • apt-get install zmap sshpass -y --force-yes
  • Scans for networks with an open port 22 using Zmap and uses the credentials username: pi and password: raspberry or raspberryraspberry993311 to drop a copy and execute it.
  • Executes the following commands to change the password of user pi:
    • usermod -p \$6\$vGkGPKUr\$heqvOhUzvbQ66Nb0JGCijh/81sG1WACcZgzPn8A0Wn58hHXWqy5yOgTlYJEbOjhkHD0MRsAkfJgjU/ioCYDeR1 pi
  • Allowed root to log in using this ssh key:
    • {BLOCKED}SIufmqpqg54D6s4J0L7XV2kep0rNzgY1S1IdE8HDef7z1ipBVuGTygGsq+x4yVnxveGshVP48YmicQHJMCIljmn6Po0RMC48qihm/9ytoEYtkKkeiTR02c6DyIcDnX3QdlSmEqPqSNRQ/XDgM7qIB/VpYtAhK/7DoE8pqdoFNBU5+JlqeWYpsMO+qkHugKA5U22wEGs8xG2XyyDtrBcw10xz+M7U8Vpt0tEadeV973tXNNNpUgYGIFEsrDEAjbMkEsUw+iQmXg37EusEFjCVjBySGH3F+EQtwin3YmxbB9HRMzOIzNnXwCFaYU5JjTNnzylUBp/XB6B
  • Executes the following commands so that it will run upon boot:
    • sudo sh -c "echo '#!/bin/sh -e' > /etc/rc.local"
    • sudo sh -c "echo /opt/$NEWMYSELF >> /etc/rc.local"
    • sudo sh -c "echo 'exit 0' >> /etc/rc.local"

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.676.09
FIRST VSAPI PATTERN DATE: 11 Feb 2020
VSAPI OPR PATTERN File: 15.677.00
VSAPI OPR PATTERN Date: 12 Feb 2020

Step 1

Scan your computer with your Trend Micro product to clean files detected as Backdoor.SH.PIMINE.AA. 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:

Step 2

Scan your computer with your Trend Micro product to delete files detected as Backdoor.SH.PIMINE.AA. 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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