Analysis by: Rheniel Rhay Ramos

ALIASES:

Ransom.Rapid (Malwarebytes); W32/Injector.DVHR!tr (Fortinet); Trojan-Banker.Win32.Jimmy.aap (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This ransomware is downloaded from Greenflash-Sundown exploit kit's use of CVE-2018-4878.

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 the initially executed copy of itself.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 231,424 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 10 Mar 2018
Payload: Encrypts files, Displays message/message boxes

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 and executes them:

  • %User Temp%\svchosta.exe (Windows Vista or above)
  • %Application Data%\svchosta.exe (Windows XP or below)

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It drops the following files:

  • %System Root%\Users\Public\PUBLIC (Windows Vista or above)
  • %System Root%\Documents and Settings\Default User\PUBLIC (Windows XP or below)
  • %System Root%\Users\Public\UNIQUE_ID_DO_NOT_REMOVE (Windows Vista or above)
  • %System Root%\Documents and Settings\Default User\UNIQUE_ID_DO_NOT_REMOVE (Windows XP or below)

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

It drops and executes the following files:

  • %User Temp%\svchostaaexe.bat (Windows Vista or above) -> used to delete initial copy and itself
  • %Application Data%\svchostaaexe.bat (Windows XP or below) -> used to delete initial copy and itself

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Autostart Technique

This Ransomware enables its automatic execution at every system startup by dropping the following copies of itself into the Windows Common Startup folder:

  • %User Startup%\start.bat -> used to execute dropped copy

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Ransomware displays a pop-up window with the following message:


It does the following:

  • It encrypts files on all drives except for the following:
    • CD-ROM drive

It deletes the initially executed copy of itself

Ransomware Routine

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

  • DECRYPT_INFORMATION.html
  • UNIQUE_ID_DO_NOT_REMOVE
  • *exe
  • *dll
  • *lnk
  • *ini
  • *hrmlog

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

  • Windows
  • AhnLab
  • Microsoft
  • Chrome
  • Mozilla
  • $Recycle.Bin
  • WINDOWS

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

  • {Folder Containing Encrypted Files}\DECRYPT_INFORMATION.html

NOTES:

The Ransom note displays the following:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.124.05
FIRST VSAPI PATTERN DATE: 12 Mar 2018
VSAPI OPR PATTERN File: 14.125.00
VSAPI OPR PATTERN Date: 13 Mar 2018

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_LOCKY.TIAOKAI

[ 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

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 Temp%\svchostaaexe.bat (Windows Vista or above)
  • %System Root%\Users\Public\PUBLIC (Windows Vista or above)
  • %System Root%\Users\Public\UNIQUE_ID_DO_NOT_REMOVE (Windows Vista or above)
  • %Application Data%\svchostaaexe.bat (Windows XP or below)
  • %System Root%\Documents and Settings\Default User\PUBLIC (Windows XP or below)
  • %System Root%\Documents and Settings\Default User\UNIQUE_ID_DO_NOT_REMOVE (Windows XP or below)
  • {Folder Containing Encrypted Files}\DECRYPT_INFORMATION.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_LOCKY.TIAOKAI. 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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