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RANSOM_CRYPKEYIV.A

June 15, 2016
 Analysis by: Rhena Inocencio
 ALIASES:

Trojan-Ransom.Win32.Crypren.acsa (Kaspersky), Ransomware-FNA!C0B834F87051 (McAfee)

 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

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:

19,456 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

13 Jun 2016

Payload:

Encrypts files, Displays message/message boxes

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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • MyAppMutex

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files and appends the extension .7h9r

Other Details

This Trojan encrypts files with the following extensions:

  • *.3gp
  • *.7z
  • *.apk
  • *.avi
  • *.bmp
  • *.cdr
  • *.cer
  • *.chm
  • *.conf
  • *.css
  • *.csv
  • *.dat
  • *.db
  • *.dbf
  • *.dbx
  • *.djvu
  • *.doc
  • *.docm
  • *.docx
  • *.epub
  • *.fb2
  • *.flv
  • *.gif
  • *.gz
  • *.ibooks
  • *.iso
  • *.jpeg
  • *.jpg
  • *.key
  • *.md2
  • *.mdb
  • *.mdf
  • *.mht
  • *.mhtm
  • *.mkv
  • *.mobi
  • *.mov
  • *.mp3
  • *.mp4
  • *.mpeg
  • *.mpg
  • *.pdf
  • *.pict
  • *.pkg
  • *.png
  • *.pps
  • *.ppsx
  • *.ppt
  • *.pptx
  • *.psd
  • *.rar
  • *.rtf
  • *.sav
  • *.scr
  • *.swf
  • *.tbl
  • *.tif
  • *.tiff
  • *.torrent
  • *.txt
  • *.vsd
  • *.wmv
  • *.xls
  • *.xlsx
  • *.xml
  • *.xps
  • *.zip
  • *.ckp
  • *.java
  • *.py
  • *.cpp
  • *.asm
  • *.c
  • *.js
  • *.cs
  • *.php
  • *.rb
  • *.rbw
  • *.dacpac
  • *.db3
  • *.dcx
  • *.mrg
  • *.sql
  • *.sqlite
  • *.sqlite3
  • *.sqlitedb

It drops the following file(s)/component(s):

  • {folder containing encrypted files}\README_.TXT - ransom note

It does the following:

  • It enumerates drives and encrypts files in those drives
  • It deletes itself via cmd.exe after its encryption routine:
    • "C:\Windows\System32\cmd.exe" /C choice /C Y /N /D Y /T 3 & Del "{malware path and filename}"

NOTES:

The dropped ransom note README_.TXT contains instructions how to decrypt the files:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.588.08

FIRST VSAPI PATTERN DATE:

13 Jun 2016

VSAPI OPR PATTERN File:

12.589.00

VSAPI OPR PATTERN Date:

14 Jun 2016

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Identify and terminate files detected as RANSOM_CRYPKEYIV.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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.  
  • README_.TXT

Step 5

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

Step 6

Restore encrypted files from backup.


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