Analysis by: Paul Steven Nadera
ALIASES:

a variant of Win32/Kryptik.HCLZ trojan (NOD32); Trojan:Win32/Mokes.PVD!MTB (Microsoft); RDN/Ransom (NAI)

 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.

As of this writing, the said sites are inaccessible.

However, as of this writing, the said sites are inaccessible.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 712,192 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Apr 2020
Payload: Connects to URLs/IPs, Collects system information, 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} -> where downloaded files and copies of itself are located
  • %SystemRoot%\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).)

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:

  • %SystemRoot%\SystemID\PersonalID.txt -> contains a unique identifier for the infected machine
  • %AppDataLocal%\bowsakkdestx.txt -> contains response from the CnC server

(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:

  • icacls "%AppDataLocal%\{GUID}" /deny *S-1-1-0:(OI)(CI)(DE,DC) -> changes access controls of the malware file
  • "{Malware Path}\{Malware Filename}.exe" --Admin IsNotAutoStart IsNotTask -> malware process 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}
  • {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 = "%AppLocalData%\{GUID}\{Malware Filename}.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}f.top/files/penelop/updatewin.exe
  • http://{BLOCKED}f.top/files/penelop/updatewin1.exe
  • http://{BLOCKED}f.top/files/penelop/updatewin2.exe
  • http://{BLOCKED}f.top/files/penelop/3.exe
  • http://{BLOCKED}f.top/files/penelop/4.exe
  • http://{BLOCKED}f.top/files/penelop/5.exe

As of this writing, the said sites are inaccessible.

Information Theft

This Ransomware gathers the following data:

  • Computer Name
  • User Name
  • MAC Address

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 does the following:

  • Connects to the URL to get the arguments needed for "--Service" and "--ForNetRes" to perform its routine:
    • http://{BLOCKED}f.top/ydtftysdtyftysdfsdpen3/get.php?pid={MD5 hash of MAC address of the machine}&first={True/False}

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

It adds the following scheduled tasks:

  • Task Name: Time Trigger Task
    • Trigger: Every 5 minutes
    • Task to be run: %AppDataLocal%\{GUID}\{Malware Filename}.exe --Task

(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).)

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
  • .sys
  • .ini
  • .DLL
  • .dll
  • .blf
  • .bat
  • .lnk
  • .regtrans-ms

It avoids encrypting files found in the following folders:

  • C:\SystemID\
  • C:\Users\Default User\
  • C:\Users\Public\
  • C:\Users\All Users\
  • C:\Users\Default\
  • C:\Documents and Settings\
  • C:\ProgramData\
  • C:\Recovery\
  • C:\System Volume Information\
  • C:\Users\%username%\AppData\Roaming\
  • C:\Users\%username%\AppData\Local\
  • C:\Windows\
  • C:\PerfLogs\
  • C:\ProgramData\Microsoft\
  • C:\ProgramData\Package Cache\
  • C:\Users\Public\
  • C:\$Recycle.Bin\
  • C:\$WINDOWS.~BT\
  • C:\dell\
  • C:\Intel\
  • C:\MSOCache\
  • C:\Program Files\
  • C:\Program Files (x86)\
  • C:\Games\
  • C:\Windows.old\
  • D:\Users\%username%\AppData\Roaming\
  • D:\Users\%username%\AppData\Local\
  • D:\Windows\
  • D:\PerfLogs\
  • D:\ProgramData\Desktop\
  • D:\ProgramData\Microsoft\
  • D:\ProgramData\Package Cache\
  • D:\Users\Public\
  • D:\$Recycle.Bin\
  • D:\$WINDOWS.~BT\
  • D:\dell\
  • D:\Intel\
  • D:\MSOCache\
  • D:\Program Files\
  • D:\Program Files (x86)\
  • D:\Games\
  • E:\Users\%username%\AppData\Roaming\
  • E:\Users\%username%\AppData\Local\
  • E:\Windows\
  • E:\PerfLogs\
  • E:\ProgramData\Desktop\
  • E:\ProgramData\Microsoft\
  • E:\ProgramData\Package Cache\
  • E:\Users\Public\
  • E:\$Recycle.Bin\
  • E:\$WINDOWS.~BT\
  • E:\dell\
  • E:\Intel\
  • E:\MSOCache\
  • E:\Program Files\
  • E:\Program Files (x86)\
  • E:\Games\
  • F:\Users\%username%\AppData\Roaming\
  • F:\Users\%username%\AppData\Local\
  • F:\Windows\
  • F:\PerfLogs\
  • F:\ProgramData\Desktop\
  • F:\ProgramData\Microsoft\
  • F:\Users\Public\
  • F:\$Recycle.Bin\
  • F:\$WINDOWS.~BT\
  • F:\dell\
  • F:\Intel\

It appends the following extension to the file name of the encrypted files:

  • .mado

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

  • {Encrypted Directory}\_readme.txt

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.810.04
FIRST VSAPI PATTERN DATE: 17 Apr 2020
VSAPI OPR PATTERN File: 15.811.00
VSAPI OPR PATTERN Date: 18 Apr 2020

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.XXPE50FFF034

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

[ Learn More ]

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
    • SysHelper = "%AppLocalData%\{GUID}\{Malware Filename}.exe --AutoStart"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
    • SysHelper = 1

Step 6

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Time Trigger Task - %AppLocalData%\{GUID}\{Malware Filename}.exe --Task

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. 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:

  1. 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.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 7

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.  
  • %AppDataLocal%\{GUID}\{Malware Filename}.exe
  • %AppDataLocal%\bowsakkdestx.txt
  • %SystemRoot%\SystemID\PersonalID.txt
  • {Encrypted Directory}\_readme.txt

Step 8

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.
  • %AppDataLocal%\{GUID}
  • %SystemRoot%\SystemID

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.STOP.CM. 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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