Analysis by: Jemimah Mae Molina

 PLATFORM:

Linux

 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: 3,150,056 bytes
File Type: ELF
Memory Resident: Yes
Initial Samples Received Date: 19 Dec 2019
Payload: Connects to URLs/IPs

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.

Installation

This Trojan adds the following processes:

  • sleep 15s && cd /var/tmp; echo {base-64 encoded commands} | base64 --decode | bash

Other Details

This Trojan does the following:

  • It performs SSH brute force to the list of IP addresses from the [IPs/IPs Port FILE] input file and uses the credentials given by the [[USER PASS] FILE] input file.
  • It acts as a spreader by downloading and executing the main module of the malware from the following FTP sites:
    • {BLOCKED}.{BLOCKED}.148.129:22
    • {BLOCKED}.{BLOCKED}.148.125:22
  • The downloaded file is saved using the following name:
    • dota3.tar.gz → detected as Trojan.Linux.DITERTAG.USELVLA19

It accepts the following parameters:

  • Usage: scan [OPTIONS] [[USER PASS]] FILE] [IPs/IPs Port FILE]
    Options:
    • -t [NUMTHREADS] → specifies the number of threads to be used
    • -m [MODE] → indicates scan mode
    • -f [FINAL SCAN] → performs a final scan on found servers
    • -i [IP SCAN] → scans specific IP range
    • -P [PASSWORD] → changes password
    • -s [TIMEOUT] → changes timeout
    • -S [2ndTIMEOUT] → changes second timeout
    • -p [PORT] → specifies port to connect to
    • -c [REMOTE-COMMAND] → executes arbitrary commands on connect
    • -h → shows this help
    • -H 1 → shows extra help

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.568.04
FIRST VSAPI PATTERN DATE: 19 Dec 2019
VSAPI OPR PATTERN File: 15.569.00
VSAPI OPR PATTERN Date: 20 Dec 2019

Scan your computer with your Trend Micro product to delete files detected as Trojan.Linux.SSHBRUTE.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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