Ransom.Linux.ELFACRYPT.B

June 20, 2019
 Analysis by: Patrick Angelo Roderno
 ALIASES:

HEUR:Trojan-Ransom.Linux.Agent.a (KASPERSKY); Trojan:Win32/Occamy.B (MICROSOFT); Mal/Generic-S (SOPHOS)

 PLATFORM:

Linux

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It encrypts files with specific file extensions. It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

1,328,128 bytes

File Type:

ELF

Memory Resident:

No

Initial Samples Received Date:

10 Nov 2017

Arrival Details

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Other Details

This Ransomware does the following:

  • If the parameter -k is not specified, it searches for the file ./pub.key and uses it as the public key for encryption

It accepts the following parameters:

  • -k {file containing the public key to be used}
  • -d {target path for encryption}

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .7z
  • .asp
  • .aspx
  • .bak
  • .c
  • .conf
  • .cp
  • .css
  • .doc
  • .doc
  • .docx
  • .ecrypt
  • .err
  • .FRM
  • .FRM
  • .gif
  • .gz
  • .gz
  • .h
  • .html
  • .html
  • .ini
  • .jpeg
  • .jpg
  • .js
  • .jsp
  • .key
  • .mail
  • .MYD
  • .MYD
  • .MYI
  • .MYI
  • .opt
  • .php
  • .php
  • .php5
  • .png
  • .ppt
  • .pst
  • .py
  • .rar
  • .rb
  • .rb
  • .sh
  • .sh
  • .sql
  • .tar
  • .txt
  • .xls
  • .xlsx
  • .xml
  • .zip

It encrypts files found in the following folders:

  • /etc
  • /usr
  • /lib
  • /bin
  • /sbin
  • /proc
  • /boot
  • /dev
  • /selinux
  • /srv
  • /sys
  • /lib64

It appends the following extension to the file name of the encrypted files:

  • /encrypted_{date of infection}_{alternative representation of date of infection}.enc

It leaves text files that serve as ransom notes containing the following text:

  • Your file has been encrypted,please check out your email 'server@koreaidc.com' or contact exlo0poi3@outlook.com to get decrypting details

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.186.03

FIRST VSAPI PATTERN DATE:

20 Jun 2019

VSAPI OPR PATTERN File:

15.187.00

VSAPI OPR PATTERN Date:

21 Jun 2019

Scan your computer with your Trend Micro product to delete files detected as Ransom.Linux.ELFACRYPT.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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