Analysis by: Marcus Ma. Antonio Capistrano
ALIASES:

Trojan-Ransom.Win32.Crypmod.ytx (KASPERSKY), Ransom:Win32/Ergop.D (MICROSOFT), Win32/Filecoder.FV trojan(NOD32)

 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 deletes itself after execution. It is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 238,080 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 28 Dec 2017
Payload: Drops files, Terminates processes, 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 into the affected system:

  • %Application Data%\{running malware filename}

(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.)

It drops the following files:

  • %System Root%\Users\Public\AE09C984DF6E74640B3271EADB5DD7C65FDE806235B2CDA478E0EFA9129C09E7

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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\RunOnce
BrowserUpdateCheck = %Application Data%\{running malware filename}

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • sql
  • outlook
  • ssms
  • postgre
  • 1c
  • excel
  • word

Other Details

This Ransomware does the following:

  • It deletes all shadow copies by executing the following command:
    • vssadmin.exe Delete Shadows /All /Quiet
  • The malware clears the remote desktop protocol connection history using the commands:
    • reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default" /va /f
    • reg delete "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers" /f
    • reg add "HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers"
    • cd %userprofile%\documents\
    • attrib Default.rdp -s -h
    • del Default.rdp
  • The malware deletes all Event Viewer log files using the commands:
    • for /F "tokens=*" %1 in ('wevtutil.exe el') DO wevtutil.exe cl "%1"

It deletes itself after execution.

It is capable of encrypting files in the affected system.

Ransomware Routine

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

  • ..doc
  • Read___ME.html
  • AE09C984DF6E74640B3271EADB5DD7C65FDE806235B2CDA478E0EFA9129C09E7
  • {Running malware file name}

It avoids encrypting files found in the following folders:

  • Windows
  • Microsoft
  • Microsoft Help
  • Windows App Certification Kit
  • Windows Defender
  • ESET
  • COMODO
  • Windows NT
  • Windows Kits
  • Windows Mail
  • Windows Media Player
  • Windows Multimedia Platform
  • Windows Phone Kits
  • Windows Phone Silverlight Kits
  • Windows Photo Viewer
  • Windows Portable Devices
  • Windows Sidebar
  • WindowsPowerShell
  • NVIDIA Corporation
  • Microsoft.NET
  • Internet Explorer
  • Kaspersky Lab
  • McAfee
  • Avira
  • spytech software
  • sysconfig
  • Avast
  • Dr.Web
  • Symantec
  • Symantec_Client_Security
  • system volume information
  • AVG
  • Microsoft Shared
  • Common Files
  • Outlook Express
  • Movie Maker
  • Chrome
  • Mozilla Firefox
  • Opera
  • YandexBrowser
  • ntldr
  • Wsus
  • ProgramData

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

  • ..doc

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

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.872.09
FIRST VSAPI PATTERN DATE: 29 Dec 2017
VSAPI OPR PATTERN File: 13.873.00
VSAPI OPR PATTERN Date: 30 Dec 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

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\RunOnce
    • BrowserUpdateCheck = %Application Data%\{running malware filename}

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%\{running malware filename}
  • %System Root%\Users\Public\AE09C984DF6E74640B3271EADB5DD7C65FDE806235B2CDA478E0EFA9129C09E7
  • {path of encrypted files}\Read___ME.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPMOD.R002C0RLT17. 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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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