Analysis by: Ryan Paolo Maglaque

 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 drops files as ransom note.

  TECHNICAL DETAILS

File Size: 455,680 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 24 Apr 2017
Payload: Encrypts files, Drops 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 files:

  • %Desktop%\DECODE_ALL_FILES.bat
  • {Malware Directory}\image.jpg

(Note: %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.)

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
SystemCrp = {Malware File}

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = {Malware Directory}\image.jpg

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

It sets the system's desktop wallpaper to the following image:

Other Details

This Ransomware does the following:

  • Display the following window:

  • Updates the configuration file after encryption

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file path:

  • tmp
  • winnt
  • Application Data
  • AppData
  • Program Files (x86)
  • Program Files
  • temp
  • $Recycle.bin
  • System Volume Information
  • Boot
  • bootmgr
  • Windows
  • How_return_files.txt
  • DECODE_ALL_FILES.BAT
  • thumbs.db

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

  • .helppme@india.com.ID{8 Random Numbers}

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

  • {Encrypted Files Directory}\How_return_files.txt
  • {Malware Directory}\How_return_files.txt

It leaves text files that serve as ransom notes containing the following text:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.376.02
FIRST VSAPI PATTERN DATE: 02 May 2017
VSAPI OPR PATTERN File: 13.377.00
VSAPI OPR PATTERN Date: 03 May 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
    • SystemCrp = {Malware File}

Step 5

Search and delete this file

[ 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%\DECODE_ALL_FILES.bat
  • {Malware Directory}\image.jpg
  • {Malware Directory}\How_return_files.txt
  • {Encrypted Files Directory}\How_return_files.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_DONTSLIP.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 7

Reset your Desktop properties

[ Learn More ]

Step 8

Restore encrypted files from backup.


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