Analysis by: Rheniel Rhay Ramos
ALIASES:

Trojan-Ransom.Win32.Crypren.adys (Kaspersky); Ransom.Jigsaw (Malwarebytes); Ransom.HiddenTear!g1 (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

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 connects to certain websites to send and receive information.

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

  TECHNICAL DETAILS

File Size: 197,120 bytes
Memory Resident: No
Initial Samples Received Date: 13 Nov 2017
Payload: Connects to URLs/IPs, Displays message/message boxes, Displays windows, Encrypts files

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.

Installation

This Ransomware drops the following copies of itself depending on the platform/operating system of the affected computer:

  • %User Temp%\{Malware Name}.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Random} = "%User Temp%\{Malware Name}.exe"
Wherein {Random} could be any of the following:

  • Validator
  • Adobe
  • Validation
  • DefinatelyNotMalware
  • Default
  • WindowsLogon
  • Microsoft
  • Microsoft Word

Other Details

This Ransomware connects to the following website to send and receive information:

  • http://{BLOCKED}i.com/sc/gettime.php
  • http://{BLOCKED}i.com/sc/register.php?

It displays a pop-up window with the following message:


It does the following:

  • It will open the following websites if you click on the Article links on the pop-up window:
    • http://www.bleepingcomputer.com/news/security/jigsaw-ransomware-decrypted-will-delete-your-files-until-you-pay-the-ransom/
    • https://security.googleblog.com/2010/09/stay-safe-while-browsing.html
  • It displays a window which connects to the following website if you agreed to install the .NET framework:
    • https://www.microsoft.com/en-us/download/search.aspx?q=.net%20framework

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .txt

It encrypts files found in the following folders:

  • %User Profile%

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

  • .encrypted

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.808.04
FIRST VSAPI PATTERN DATE: 13 Nov 2017
VSAPI OPR PATTERN File: 13.809.00
VSAPI OPR PATTERN Date: 14 Nov 2017

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

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Random} = "%User Temp%\{Malware Name}.exe"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_JIGSAW.WG. 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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