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Ransom.Win32.STOP.THOABDAI

February 09, 2019
 Analysis by: John Donnie Celestre
 Modified by: Maureen Reyes
 ALIASES:

Trojan.Win32.Chapak.bugg (KASPERSKY); a variant of Win32/Kryptik.GOWQ trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • 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 attempts to access certain websites. However, the websites are inaccessible as of this writing.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

335,360 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Feb 2019

Payload:

Downloads files, Connects to URLs/IPs

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:

  • %AppDataLocal%\{ID}\{Malware Filename}.exe

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

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
SysHelper = %AppDataLocal%\{ID}\{Malware Filename}.exe --AutoStart

Download Routine

This Ransomware connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}s.ug/xxx/updatewin1.exe
  • http://{BLOCKED}s.ug/xxx/updatewin2.exe
  • http://{BLOCKED}s.ug/xxx/updatewin.exe
  • http://{BLOCKED}s.ug/xxx/3.exe
  • http://{BLOCKED}s.ug/TRytaersdasdahjsdhjasGGGHGHfsdOLD/get.php?pid=135E1384A44D7DC0444C191A75BD82E4

Other Details

This Ransomware attempts to access certain websites. However, the websites are inaccessible as of this writing.

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .adobe

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

  • {Directory}:/_openme.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.770.05

FIRST VSAPI PATTERN DATE:

24 Jan 2019

VSAPI OPR PATTERN File:

14.771.00

VSAPI OPR PATTERN Date:

25 Jan 2019

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • SysHelper = %AppDataLocal%\{ID}\{Malware Filename}.exe --AutoStart

Step 5

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.
  • {Directory}:/_openme.txt

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.STOP.THOABDAI. 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 7

Restore encrypted files from backup.


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