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RANSOM_CRYPTEAR.B

December 23, 2015
 Analysis by: Jennifer Gumban
 ALIASES:

Ransom:MSIL/Ryzerlo.A (Microsoft)

 PLATFORM:

Windows

 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.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

213,504 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Dec 2015

Payload:

Encrypts files, Connects to URLs/IPs, Steals information

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 copies of itself into the affected system and executes them:

  • %User Profile%\able.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops the following files:

  • %User Temp%\text.txt - contains machine name and encryption key
  • %Desktop%\MENSAGEM.txt - ransom note

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • http://i.imgur.com/{BLOCKED}O.jpg

It saves the files it downloads using the following names:

  • %User Profile%\ran.jpg - ransom note

Information Theft

This Trojan gathers the following information on the affected computer:

  • Machine Name
  • User Name

NOTES:

It connects to the following website to send information:

  • http://www.{BLOCKED}n.com/hidden-tear/write.php?info={MachineName}-{UserName}%20{Generated Password for decryption}

It encrypts files with the following extensions in the %User Profile% sub folders and appends .locked as the new file extension of the encrypted files:

  • .txt
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .odt
  • .jpg
  • .png
  • .csv
  • .sql
  • .mdb
  • .sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml
  • .psd

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.216.02

FIRST VSAPI PATTERN DATE:

17 Dec 2015

VSAPI OPR PATTERN File:

12.217.00

VSAPI OPR PATTERN Date:

18 Dec 2015

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.  
  • %User Profile%\ran.jpg
  • %User Temp%\text.txt
  • %Desktop%\MENSAGEM.txt

Step 3

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPTEAR.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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