Analysis by: Johnlery Triunfante

ALIASES:

RiskTool.Win32.Crypter.byl (KASPERSKY); Gen:Variant.MSILPerseus.100164 (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.

  TECHNICAL DETAILS

File Size: 5,108,224 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 18 May 2017
Payload: Displays message/message boxes, 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 files:

  • %User Profile%\license.bat - Calls runtime.exe for encryption. Also contains the AES encryption key.
  • %User Profile%\runtime.exe - Encryptor/decryptor file.
  • %Desktop%\decrypt.bat - Calls runtime.exe for decryption. Also contains the AES encryption key.
  • %Desktop%\runtime.exe - Encryptor/decryptor file.

(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.. %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.)

Other Details

This Ransomware does the following:

  • This ransomware does not display its ransom note if there is a command prompt open.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .rbxl
  • .rbxm
  • .rbxmx
  • .lua

It encrypts files found in the following folders:

  • %User Profile%\
  • %User Profile%\{Subfolders}

(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:

  • .aes

NOTES:

This ransomware displays the following window as its ransom note, which has a password of "PooPoo".

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.430.08
FIRST VSAPI PATTERN DATE: 26 May 2017
VSAPI OPR PATTERN File: 13.431.00
VSAPI OPR PATTERN Date: 27 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

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%\license.bat
  • %User Profile%\runtime.exe
  • %Desktop%\decrypt.bat
  • %Desktop%\runtime.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_ROBLOCKER.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 5

Restore encrypted files from backup.


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