Author: Henry Alarcon Jr.   

 

Linux/Gafgyt.a (McAfee), ELF/Gafgyt.BJ!tr (Fortinet)

 PLATFORM:

Linux

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Backdoor

  • Destructiveness:
    No

  • Encrypted:
    No

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Dropped by other malware, Downloaded from the Internet

This is an updated Bashlite malware designed to add infected internet-of-things devices to a distributed-denial-of-service (DDoS) botnet.

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: 82,145 bytes
File type: ELF
Memory resident: No
INITIAL SAMPLES RECEIVED DATE: 06 August 2019
PAYLOAD: Connects to URLs/IPs, Downloads files

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.

Backdoor Routine

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

  • UDP - UDP flood
  • STD - STD flood
  • TCP - TCP flood
  • CLOUDFLARE - HTTP Flood w/ CloudFlare protection bypass
  • HTTP - HTTP Flood
  • STOMP - STD + UDP Flood
  • RAID - STD + TCP Flood
  • UPDATE - downloaded updated binary from C&C
  • CNC - set CNC
  • STOP - Stop bot operation

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

  • {BLOCKED}.{BLOCKED}.7.231:46216

Information Theft

This Backdoor gathers the following data:

  • Linux distro - OpenSuse/REHL or Centos/Gentoo/Ubuntu or Debian/Unknown
  • files -Presence of the following files:
    • /usr/sbin/telnetd
    • /usr/bin/python
    • /usr/bin/python3
  • device - returns the string “SSH” if there is a file “/usr/sbin/telnetd”, otherwise, it will return “Unknown Device”
  • Port - returns the string “22” if the four files mentioned above is found, otherwise, it will return “Unknown Port”

Other Details

This Backdoor does the following:

  • It is capable of updating itself and download binaries by accessing the following URL:
    • {BLOCKED}.{BLOCKED}.7.231/bins.sh

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 14.918.08
First VSAPI Pattern Release Date: 04 April 2019
VSAPI OPR PATTERN-VERSION: 14.919.00
VSAPI OPR PATTERN DATE: 05 April 2019

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Linux.BASHLITE.SMJC. 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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