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RANSOM_SNAKELOCK.A

February 14, 2018
 Analysis by: Christian Noel Olalia
 ALIASES:

Trojan-Ransom.Win32.Gen.esp (KASPERSKY); Trojan.Gen.2 (NORTON); Trojan.GenericKD.12108461 (BITDEFENDER)

 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 encrypts files with specific file extensions. It encrypts files found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

5,468,348 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

24 Jul 2017

Payload:

Drops files, Encrypts files, Displays graphics/image

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 component file(s):

  • %User Temp%\_MEI{random numbers}\Crypto.Cipher._AES.pyd
  • %User Temp%\_MEI{random numbers}\Microsoft.VC90.CRT.manifest
  • %User Temp%\_MEI{random numbers}\SnakeLocker.exe.manifest
  • %User Temp%\_MEI{random numbers}\_ctypes.pyd
  • %User Temp%\_MEI{random numbers}\_hashlib.pyd
  • %User Temp%\_MEI{random numbers}\_multiprocessing.pyd
  • %User Temp%\_MEI{random numbers}\_socket.pyd
  • %User Temp%\_MEI{random numbers}\_ssl.pyd
  • %User Temp%\_MEI{random numbers}\bz2.pyd
  • %User Temp%\_MEI{random numbers}\msvcm90.dll
  • %User Temp%\_MEI{random numbers}\msvcp90.dll
  • %User Temp%\_MEI{random numbers}\msvcr90.dll
  • %User Temp%\_MEI{random numbers}\pyexpat.pyd
  • %User Temp%\_MEI{random numbers}\python27.dll
  • %User Temp%\_MEI{random numbers}\pywintypes27.dll
  • %User Temp%\_MEI{random numbers}\select.pyd
  • %User Temp%\_MEI{random numbers}\unicodedata.pyd
  • %User Temp%\_MEI{random numbers}\win32api.pyd
  • %User Temp%\_MEI{random numbers}\win32console.pyd
  • %User Temp%\_MEI{random numbers}\win32event.pyd
  • %User Temp%\_MEI{random numbers}\win32gui.pyd
  • %User Temp%\_MEI{random numbers}\Include\pyconfig.h

(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.)

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\IExplore\
WWW_OpenURLNewWindow
ProcessName = iexplore.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\DDECache\IExplore\
WWW_OpenURLNewWindow
WindowClassName = DDEMLMom

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .asp
  • .bak
  • .bat
  • .bmp
  • .cmd
  • .cpp
  • .dbf
  • .doc
  • .docx
  • .dot
  • .gif
  • .hta
  • .htm
  • .html
  • .jpeg
  • .jpg
  • .js
  • .key
  • .mdb
  • .mdf
  • .ods
  • .odt
  • .pdf
  • .php
  • .png
  • .pot
  • .ppt
  • .pptx
  • .rar
  • .rtf
  • .txt
  • .wmdb
  • .vbs
  • .xbap
  • .xls
  • .xlsx
  • .xlt
  • .xlw
  • .xml
  • .xps
  • .zip

It encrypts files found in the following folders:

  • %AppDataLocal%\
  • %Application Data%\
  • %Desktop%\
  • %User Profile%\Documents\

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in 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.. %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:

  • .snake

It drops the following file(s) as ransom note:

  • %Desktop%\INSTRUCTIONS-README.html

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.552.08

FIRST VSAPI PATTERN DATE:

24 Jul 2017

VSAPI OPR PATTERN File:

13.553.00

VSAPI OPR PATTERN Date:

25 Jul 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

Identify and terminate files detected as RANSOM_SNAKELOCK.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

Restart in Safe Mode

[ Learn More ]

Step 5

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\Explorer\FileExts\DDECache\IExplore\WWW_OpenURLNewWindow
    • ProcessName = iexplore.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\DDECache\IExplore\WWW_OpenURLNewWindow
    • WindowClassName = DDEMLMom

Step 6

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.
  • %Desktop%\INSTRUCTIONS-README.html
  • %User Temp%\_MEI{random numbers}\Crypto.Cipher._AES.pyd
  • %User Temp%\_MEI{random numbers}\Microsoft.VC90.CRT.manifest
  • %User Temp%\_MEI{random numbers}\SnakeLocker.exe.manifest
  • %User Temp%\_MEI{random numbers}\_ctypes.pyd
  • %User Temp%\_MEI{random numbers}\_hashlib.pyd
  • %User Temp%\_MEI{random numbers}\_multiprocessing.pyd
  • %User Temp%\_MEI{random numbers}\_socket.pyd
  • %User Temp%\_MEI{random numbers}\_ssl.pyd
  • %User Temp%\_MEI{random numbers}\bz2.pyd
  • %User Temp%\_MEI{random numbers}\msvcm90.dll
  • %User Temp%\_MEI{random numbers}\msvcp90.dll
  • %User Temp%\_MEI{random numbers}\msvcr90.dll
  • %User Temp%\_MEI{random numbers}\pyexpat.pyd
  • %User Temp%\_MEI{random numbers}\python27.dll
  • %User Temp%\_MEI{random numbers}\pywintypes27.dll
  • %User Temp%\_MEI{random numbers}\select.pyd
  • %User Temp%\_MEI{random numbers}\unicodedata.pyd
  • %User Temp%\_MEI{random numbers}\win32api.pyd
  • %User Temp%\_MEI{random numbers}\win32console.pyd
  • %User Temp%\_MEI{random numbers}\win32event.pyd
  • %User Temp%\_MEI{random numbers}\win32gui.pyd
  • %User Temp%\_MEI{random numbers}\Include\pyconfig.h

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_SNAKELOCK.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 8

Restore encrypted files from backup.


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