Analysis by: Janus Agcaoili
ALIASES:

Linux.Encoder.2 (DrWeb), HEUR:Trojan-Ransom.Linux.Cryptor.b (Kaspersky), Unix.Ransomcrypt.B (Symantec)

 PLATFORM:

Unix, 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: Dropped by other malware, Downloaded from the Internet

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: 1,391,011 bytes
File Type: ELF
Memory Resident: Yes
Initial Samples Received Date: 25 Nov 2015
Payload: Encrypts 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.

Installation

This Trojan drops the following non-malicious files:

  • ./readme.crypto - Contains data to be written in README_FOR_DECRYPT.txt
  • README_FOR_DECRYPT.txt - to all folders where files are encrypted

Other Details

This Trojan encrypts files with the following extensions:

  • .php
  • .html
  • .tar
  • .gz
  • .sql
  • .js
  • .css
  • .txt
  • .pdf
  • .tgz
  • .war
  • .jar
  • .java
  • .class
  • .ruby
  • .rar
  • .zip
  • .db
  • .7z
  • .doc
  • .xls
  • .properties
  • .xml
  • .jpg
  • .jpeg
  • .png
  • .gif
  • .mov
  • .avi
  • .wmv
  • .mp3
  • .mp4
  • .wma
  • .aac
  • .wav
  • .pub
  • .docx
  • .apk
  • .exe
  • .dll
  • .tpl
  • .psd
  • .asp
  • .phtml
  • .aspx
  • .csv

It renames encrypted files using the following names:

  • {Filename}.encrypted

It does the following:

  • It also encrypts files in folders with the following strings:
    • public_html
    • webapp
    • backup
    • .git
    • .svn
  • It initially encrypt files found in the following directories:
    • /home
    • /root
    • /var/lib/mysql
    • /var/www
    • /etc/nginx
    • /etc/apache2
    • /var/log
  • It avoids encrypting files within the following directories:
    • /

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.172.01
FIRST VSAPI PATTERN DATE: 25 Nov 2015
VSAPI OPR PATTERN File: 12.173.00
VSAPI OPR PATTERN Date: 26 Nov 2015

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPTOR.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 this Knowledge Base page for more information.


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