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Ransom.Win32.DABLIO.THABAOAH

February 27, 2019
 Analysis by: Jay Garcia
 ALIASES:

Ransom:Win32/Genasom(Microsoft); Trojan.Win32.Diztakun.bkto(Kaspersky)

 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:

Downloaded from the Internet, Dropped by other malware


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.

  TECHNICAL DETAILS

File Size:

12,662,402 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Dec 2018

Payload:

Connects to URLs/IPs, Displays graphics/image, Adds registry entries

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:

  • %Windows%\SoftwareDistribution\Download\windll.exe

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

It adds the following processes:

  • vssadmin Delete Shadows /All /Quiet
  • bcdedit /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit /set {default} recoveryenabled No

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
windll = %Windows%\SoftwareDistribution\Download\windll.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableCMD = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoRun = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = 1

Other Details

This Ransomware displays the following message boxes:



It does the following:

  • Displays the following webpage if the Contact Us button is clicked:

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • 3gp
  • aac
  • aiff
  • ape
  • avi
  • bmp
  • csv
  • db
  • dbf
  • doc
  • docx
  • epub
  • flac
  • flv
  • gif
  • iso
  • jpeg
  • jpg
  • json
  • m4a
  • m4v
  • md
  • mdb
  • mkv
  • mov
  • mp3
  • mp4
  • mpeg
  • mpg
  • odp
  • ods
  • odt
  • ogg
  • pdf
  • png
  • ppt
  • pptx
  • psd
  • raw
  • rtf
  • sql
  • svg
  • swf
  • tex
  • txt
  • wav
  • wma
  • wmv
  • xls
  • xlsx
  • xml
  • yaml
  • yml

It renames encrypted files using the following names:

  • (encrypted) {filename}.{file extension}

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.680.02

FIRST VSAPI PATTERN DATE:

10 Dec 2018

VSAPI OPR PATTERN File:

14.681.00

VSAPI OPR PATTERN Date:

11 Dec 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

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • windll = %Windows%\SoftwareDistribution\Download\windll.exe

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\Policies\System
    • DisableTaskMgr = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • DisableCMD = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • NoRun = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • DisableRegistryTools = 1

Step 6

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.
  • %Windows%\SoftwareDistribution\Download\windll.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.DABLIO.THABAOAH. 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 8

Restore encrypted files from backup.


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