Backdoor.Linux.XORDDOS.B

 Analysis by: Arvin Roi Macaraeg

 ALIASES:

DoS:Linux/Xorddos.A(MICROSOFT); Linux.Xorddos(NORTON); HEUR:Trojan-DDoS.Linux.Xarcen.d(KASPERSKY)

 PLATFORM:

Linux

 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:

Dropped by other malware, Downloaded from the Internet


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.

  TECHNICAL DETAILS

File Size:

562,240 bytes

File Type:

ELF

Memory Resident:

Yes

Initial Samples Received Date:

06 Jan 2020

Payload:

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 copies of itself into the affected system:

  • /bin/{random character}

Autostart Technique

This Backdoor drops the following files:

  • /etc/cron.hourly/{random character}.sh (Cron is a time-based job scheduler in Unix-like computer operating systems)

Backdoor Routine

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

  • Execute files
  • Download files
  • Update Malware
  • Delete Files
  • Terminate Process
  • Remove Services
  • Remove Self
  • Perform DDoS attack
  • Hide Files
  • Create Services
  • Create Directory
  • Hide Port
  • Copy Files

It posts the following information to its command and control (C&C) server:

  • {BLOCKED}.{BLOCKED}.111.129:80
  • {BLOCKED}.{BLOCKED}.111.130:80
  • {BLOCKED}.{BLOCKED}.111.131:80
  • {BLOCKED}.{BLOCKED}.126.236:80
  • {BLOCKED}.{BLOCKED}.126.237:80
  • {BLOCKED}.{BLOCKED}.126.238:80
  • {BLOCKED}.{BLOCKED}.126.239:80
  • kill{BLOCKED}fly.com
  • p6.s{BLOCKED}.net
  • p6.f{BLOCKED}9.com

Information Theft

This Backdoor gathers the following data:

  • Memory Information
  • CPU Information
  • Network Speed
  • PID of Running Process
  • MD5 of Running Process

Other Details

This Backdoor does the following:

  • Drops a shell script in /etc/init.d/{random characters} folder which setups the auto-start mechanism of the malware.
  • Creates symbolic links which points to the script in /etc/init.d/{random characters}:
    • /etc/rc{1-5}.d/S90{random numbers}
    • /etc/rc.d/rc{1-5}.d/S90{random numbers}
  • Read the following from its configuration file:
    • md5 - checksum of file
    • denyip - open communication with an IP
    • filename - list of filename
    • rmfile - files to remove
  • Uses the following User Agents:
    • POST %s HTTP/1.1
      Accept:
      Accept-Language: zh-cn
      User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; TencentTraveler ; .NET CLR 1.1.4322)
      Host:
      Content-Type: application/x-www-form-urlencoded
      Content-Length:
      Connection: Keep-Alive
    • GET %s HTTP/1.1
      Accept: */*
      Accept-Language: zh-cn
      User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; TencentTraveler ; .NET CLR 1.1.4322)
      Host:
      Connection: Keep-Alive
    • GET %s HTTP/1.1
      Accept: */*
      Accept-Language: en
      User-Agent:Wget/1.12 (linux-gnu)
      Host:
      Connection: Keep-Alive

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

15.604.06

FIRST VSAPI PATTERN DATE:

06 Jan 2020

VSAPI OPR PATTERN File:

15.605.00

VSAPI OPR PATTERN Date:

07 Jan 2020

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Linux.XORDDOS.B. 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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