Analysis by: Martin Xavier Co
ALIASES:

Ransom.BTCware (Symantec); Ransom:Win32/Genasom (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • 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: 99,840 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 31 Jul 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:

  • %Application Data%\HELP.txt
  • %Desktop%\!## DECRYPT FILES ##!.txt

(Note: %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.)

Ransomware Routine

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

  • .gryphon
  • gryphon
  • !## DECRYPT FILES ##!.txt
  • BOOTMGR

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

  • $recycle.bin
  • msocache
  • ProgramData
  • programdata
  • programdata\
  • windows
  • nvidia
  • intel
  • appdata
  • inetpub
  • temp
  • program files
  • program files (x86)

It renames encrypted files using the following names:

  • {original filename}.[decr@{BLOCKED}k.li].gryphon

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

  • {folder of encrypted files}\!## DECRYPT 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: 13.566.04
FIRST VSAPI PATTERN DATE: 31 Jul 2017
VSAPI OPR PATTERN File: 13.567.00
VSAPI OPR PATTERN Date: 01 Aug 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

Scan your computer with your Trend Micro product to delete files detected as RANSOM_GRYPHON.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 4

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.  
  • %Application Data%\HELP.txt
  • %Desktop%\!## DECRYPT FILES ##!.txt

Step 5

Restore encrypted files from backup.


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