Ransom.Win32.STOP.GG
Trojan.Win32.Crypt (IKARUS)
Windows
Threat Type: Ransomware
Destructiveness: No
Encrypted: No
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.
It retrieves specific information from the affected system.
It drops files as ransom note.
TECHNICAL DETAILS
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 files:
- %System Root%\SystemID\PersonalID.txt
- %AppDataLocal%\bowsakkdestx.txt → contains the public key, deleted afterwards
- %AppDataLocal%\{GUID 2}\build2.exe
- %AppDataLocal%\{GUID 2}\build3.exe
- %Application Data%\Microsoft\Network\mstsca.exe
- %User Temp%\delself.bat → deletes the malware file
- %ProgramData%\vcruntime140.dll
- %ProgramData%\softokn3.dll
- %ProgramData%\nss3.dll
- %ProgramData%\msvcp140.dll
- %ProgramData%\mozglue.dll
- %ProgramData%\freebl3.dll
(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).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)
It drops the following copies of itself into the affected system:
- %AppDataLocal%\{GUID 1}\{Malware File Name}.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 adds the following processes:
- {Malware Path}\{Malware Filename}.exe
- {Malware Path}\{Malware Filename}.exe --Admin IsNotAutoStart IsNotTask
- icacls "%AppDataLocal%\{GUID 1}" /deny *S-1-1-0:(OI)(CI)(DE,DC)
- %AppDataLocal%\{GUID 2}\build2.exe
- %AppDataLocal%\{GUID 2}\build3.exe
- %System%\schtasks.exe /C /create /F /sc minute /mo 1 /tn "Azure-Update-Task" /tr "%Application Data%\Microsoft\Network\mstsca.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).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It creates the following folders:
- %AppDataLocal%\{GUID 1}
- %AppDataLocal%\{GUID 2}
- %System Root%\SystemID
(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 adds the following mutexes to ensure that only one of its copies runs at any one time:
- {1D6FC66E-D1F3-422C-8A53-C0BBCF3D900D}
- {FBB4BCC6-05C7-4ADD-B67B-A98A697323C1}
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 1}\{Malware File Name}.exe" --AutoStart
Other System Modifications
This Ransomware adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
SysHelper = 1
Download Routine
This Ransomware connects to the following website(s) to download and execute a malicious file:
- http://{BLOCKED}y.top/dl/build2.exe
- http://{BLOCKED}q.com/files/1/build3.exe
- http://{BLOCKED}.{BLOCKED}.46.32/install.zip
It connects to the following URL(s) to download its component file(s):
- http://{BLOCKED}q.com/test2/get.php?pid={hash}&first=true
Information Theft
This Ransomware retrieves the following information from the affected system:
- IP Address
- MAC Address
- Computer Name
- Username
Other Details
This Ransomware connects to the following URL(s) to get the affected system's IP address:
- https://{BLOCKED}i.{BLOCKED}p.ua/geo.json
It connects to the following possibly malicious URL:
- https://{BLOCKED}.me/tg_duckworld
- https://{BLOCKED}ommunity.com/profiles/76561199497218285
It does the following:
- 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 accepts the following parameters:
- --Admin → runs the malware as admin
- --AutoStart → executes using autorun registry keys
- IsAutoStart/IsNotAutoStart → executes malware as an autostart or not
- IsTask/IsNotTask → executes malware as a task or not
- --ForNetRes {argument/s from URL}
- --Service {PID of parent malware} {argument/s from URL}
It adds the following scheduled tasks:
- Task Name: Azure-Update-Task
Task Action: %Application Data%\Microsoft\Network\mstsca.exe - Task Name: Time Trigger Task
Task Action: %AppDataLocal%\{GUID 1}\{Malware Filename}.exe --Task
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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).)
Ransomware Routine
This Ransomware appends the following extension to the file name of the encrypted files:
- .kifr
It drops the following file(s) as ransom note:
- {Encrypted Directory}\_readme.txt
SOLUTION
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:
-
Ransom.Win32.TRX.XXPE50FFF067
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
Deleting Scheduled Tasks
The following {Task Name} - {Task to be run} listed should be used in the steps identified below:
- Azure-Update-Task - %Application Data%\Microsoft\Network\mstsca.exe
- Time Trigger Task - %AppDataLocal%\{GUID}\{Malware Filename}.exe --Task
For Windows 2000, Windows XP, and Windows Server 2003:
- Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
System Tools>Scheduled Tasks. - Locate each {Task Name} values listed above in the Name column.
- Right-click on the said file(s) with the aforementioned value.
- Click on Properties. In the Run field, check for the listed {Task to be run}.
- If the strings match the list above, delete the task.
For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:
- Open the Windows Task Scheduler. To do this:
• On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
• On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter. - In the left panel, click Task Scheduler Library.
- In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
- In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
- If the said string is found, delete the task.
Step 6
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
- SysHelper = 1
- SysHelper = 1
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- SysHelper = %AppDataLocal%\{GUID}\{Malware File Name}.exe --AutoStart
- SysHelper = %AppDataLocal%\{GUID}\{Malware File Name}.exe --AutoStart
Step 7
Search and delete this file
- %AppDataLocal%\{GUID}\{Malware File Name}.exe
- %System Root%\SystemID\PersonalID.txt
- %AppDataLocal%\bowsakkdestx.txt
- %AppDataLocal%\{GUID 2}\build2.exe
- %AppDataLocal%\{GUID 2}\build3.exe
- %Application Data%\Microsoft\Network\mstsca.exe
- %User Temp%\delself.bat
- %ProgramData%\vcruntime140.dll
- %ProgramData%\softokn3.dll
- %ProgramData%\nss3.dll
- %ProgramData%\msvcp140.dll
- %ProgramData%\mozglue.dll
- %ProgramData%\freebl3.dll
- {Encrypted Directory}\_readme.txt
Step 8
Search and delete these folders
- %AppDataLocal%\{GUID 1}
- %AppDataLocal%\{GUID 2}
- %System Root%\SystemID
Step 9
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.STOP.GG. 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 10
Restore encrypted files from backup.
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