Ransom.Win32.STOP.DO
Trojan:Win32/SodinokibiCrypt.AC!MTB (MICROSOFT); HEUR:Exploit.Win32.Shellcode.gen (KASPERSKY)
Windows

Threat Type: Ransomware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
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.
However, as of this writing, the said sites are inaccessible.
It drops files as ransom note. It avoids encrypting files with the following file extensions.
TECHNICAL DETAILS
803,328 bytes
EXE
Yes
31 Mar 2021
Connects to URLs/IPs, Displays message/message boxes, Encrypts files, Steals information
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 folders:
- %AppDataLocal%\{GUID}
- %System Root%\{System ID}
(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local 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 drops the following copies of itself into the affected system:
- %AppDataLocal%\{GUID}\{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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It drops the following files:
- %System Root%\{System ID}\PersonalID.txt -> contains a unique identifier for the infected machine
- %AppDataLocal%\bowsakkdestx.txt -> contains response from CnC server
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It adds the following processes:
- icacls "%AppDataLocal%\{GUID}" /deny *S-1-1-0:(OI)(CI)(DE,DC) -> changes access control of the malware file
- "{Malware Path}\{Malware Filename}.exe" --Admin IsNotAutoStart IsNotTask -> if executed with admin privileges
(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- {1D6FC66E-D1F3-422C-8A53-C0BBCF3D900D}
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%\{GUID}\{Malware Filename}{Malware Filename}.exe" --AutoStart
Other System Modifications
This Ransomware adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
SysHelper = 1
Process Termination
This Ransomware terminates the following services if found on the affected system:
- Services with the string "MYSQL"
Download Routine
This Ransomware connects to the following website(s) to download and execute a malicious file:
- http://{BLOCKED}s.top/files/iner/3.exe
- http://{BLOCKED}s.top/files/iner/4.exe
- http://{BLOCKED}s.top/files/iner/5.exe
- http://{BLOCKED}s.top/files/iner/updatewin.exe
- http://{BLOCKED}s.top/files/iner/updatewin1.exe
- http://{BLOCKED}s.top/files/iner/updatewin2.exe
Information Theft
This Ransomware gathers the following data:
- Computer Name
- MAC Address
- IP Address
- User Name
Other Details
This Ransomware connects to the following URL(s) to get the affected system's IP address:
- https://api.{BLOCKED}p.ua/geo.json
- It terminates and deletes itself on the affected system if the return of the IP address location is any of the following:
- RU (Russia)
- BY (Belarus)
- UA (Ukraine)
- AZ (Azerbaijan)
- AM (Armenia)
- TJ (Tajikistan)
- KZ (Kazakhstan)
- KG (Kyrgyzstan)
- UZ (Uzbekistan)
- SY (Syrian Arab Republic)
- It terminates and deletes itself on the affected system if the return of the IP address location is any of the following:
It does the following:
- It connects to the following URL to get the arguments needed for "--Service" and "--ForNetRes" to perform their routine:
- http://{BLOCKED}s.top/raud/get.php?pid={MD5 hash of the machine's MAC Address}&first=true
However, as of this writing, the said sites are inaccessible.
It accepts the following parameters:
- --Admin -> runs the malware as admin
- --AutoStart -> executes using autorun registry keys.
- --ForNetRes -> {argument/s from URL}
- --Service {PID of parent malware} -> {argument/s from URL}
- IsAutoStart/IsNotAutoStart -> executes malware as an autostart or not
- IsTask/IsNotTask -> executes malware as a task or not
Ransomware Routine
This Ransomware avoids encrypting files with the following strings in their file name:
- ntuser.dat
- ntuser.dat.LOG1
- ntuser.dat.LOG2
- ntuser.pol
It avoids encrypting files found in the following folders:
- {Drive}:\SystemID\
- {Drive}:\Users\Default User\
- {Drive}:\Users\Public\
- {Drive}:\Users\All Users\
- {Drive}:\Users\Default\
- {Drive}:\Documents and Settings\
- {Drive}:\ProgramData\
- {Drive}:\Recovery\
- {Drive}:\System Volume Information\
- {Drive}:\Users\%username%\AppData\Roaming\
- {Drive}:\Users\%username%\AppData\Local\
- {Drive}:\Windows\
- {Drive}:\PerfLogs\
- {Drive}:\ProgramData\Microsoft\
- {Drive}:\ProgramData\Package Cache\
- {Drive}:\Users\Public\
- {Drive}:\$Recycle.Bin\
- {Drive}:\$WINDOWS.~BT\
- {Drive}:\dell\
- {Drive}:\Intel\
- {Drive}:\MSOCache\
- {Drive}:\Program Files\
- {Drive}:\Program Files (x86)\
- {Drive}:\Games\
- {Drive}:\Windows.old\
It appends the following extension to the file name of the encrypted files:
- {Original Filename}.{Original Extension}.ekvf
It drops the following file(s) as ransom note:
- {System Root}\_readme.txt
It avoids encrypting files with the following file extensions:
- .sys
- .ini
- .DLL
- .dll
- .blf
- .bat
- .lnk
- .regtrans-ms
SOLUTION
9.800
16.658.03
15 Apr 2021
16.659.00
16 Apr 2021
Step 1
Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:
- Troj.Win32.TRX.XXPE50FFF043
Step 2
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 3
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 4
Restart in Safe Mode
Step 5
Delete this registry value
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%\{GUID}\{Malware Filename}{Malware Filename}.exe" --AutoStart
- SysHelper = "%AppDataLocal%\{GUID}\{Malware Filename}{Malware Filename}.exe" --AutoStart
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
- SysHelper = 1
- SysHelper = 1
Step 6
Search and delete this file
- %AppDataLocal%\{GUID}\{Malware Filename}.exe
- %System Root%\{System ID}\PersonalID.txt
- %AppDataLocal%\bowsakkdestx.txt
- {System Root}\_readme.txt
- {Encrypted Directory}\_readme.txt
Step 7
Search and delete this folder
- %AppDataLocal%\{GUID}
- %System Root%\{System ID}
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.STOP.DO. 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.
Step 10
Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.STOP.DO. 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:
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