ALIASES:

Worm:Win32/Drolnux.B (Microsoft); Generic-FAHD!ECE5CB682EF6 (McAfee); Trojan Horse (Symantec); Trojan-Ransom.Win32.Blocker.mgn (Kaspersky); W32/Gamarue-DA (Sophos); Trojan-Ransom.Win32.Blocker.mgn (v) (Sunbelt)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 70,594 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 31 Oct 2019

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 adds the following processes:

  • \.\%User Temp%\Rar$EX7.sr77\ashcv.exe
  • \.\%User Temp%\Rar$EX7.sr77\COM7.EXE
  • %User Temp%\Rar$EX7.sr77\vmcis.exe /stext "%User Temp%\Rar$EX7.sr77\vmcis.txt"
  • "%System%\reg.exe" ADD HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run /f /t REG_SZ /v COM_LOADER /d "\.\%System Root%\Program Files\PDF_Reader\bin\COM7.EXE"
  • REG ADD HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run /f /t REG_SZ /v COM_LOADER /d "\.\%System Root%\Program Files\PDF_Reader\bin\COM7.EXE"
  • %User Temp%\Rar$EX7.sr77\TsiWeHSA.exe

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It creates the following folders:

  • \.\%System Root%\Program Files\PDF_Reader\bin
  • \.
  • \.\%System Root%
  • \.\%System Root%\Program Files\PDF_Reader
  • %User Temp%\Rar$EX7.sr77

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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
COM_LOADER = "\.\%System Root%\Program Files\PDF_Reader\bin\COM7.EXE"

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\PDF Reader Launcher.exe

(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 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
winsvc

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
winsvc
winsvc = "1562171754"

Dropping Routine

This Ransomware drops the following files:

  • %System Root%\Program Files\PDF_Reader\PDF_Reader.exe
  • %User Temp%\Rar$EX7.sr77\COM7.EXE
  • %User Temp%\Rar$EX7.sr77\ashcv.exe
  • %System Root%\Program Files\PDF_Reader\bin\COM7.EXE

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Ransomware connects to the following possibly malicious URL:

  • http://www.{BLOCKED}e.eb2a.com/code.php?{random characters}

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.850

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Identify and terminate files detected as Ransom_Blocker.R002C0CJU19

[ 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

Delete this registry key

[ 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
    • winsvc

Step 5

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
    • COM_LOADER = "\.\%System Root%\Program Files\PDF_Reader\bin\COM7.EXE"
  • In HKEY_CURRENT_USER\Software\Microsoft\winsvc
    • winsvc = "1562171754"

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %System Root%\Program Files\PDF_Reader\PDF_Reader.exe
  • %User Temp%\Rar$EX7.sr77\COM7.EXE
  • %User Temp%\Rar$EX7.sr77\ashcv.exe
  • %System Root%\Program Files\PDF_Reader\bin\COM7.EXE

Step 7

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • \.\%System Root%\Program Files\PDF_Reader\bin
  • \.
  • \.\%System Root%
  • \.\%System Root%\Program Files\PDF_Reader
  • %User Temp%\Rar$EX7.sr77

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom_Blocker.R002C0CJU19. 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 9

Restore encrypted files from backup.


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