Ransom.Win32.STOP.AC

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 drops files as ransom note.

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%\{Hash of Machine GUID}\{Executed 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.)

It adds the following processes:

• icacls "%AppDataLocal%\{Hash of Machine GUID}" /deny *S-1-1-0:(OI)(CI)(DE,DC)
• "{Executed Malware File Path}\{Executed Malware File Name}.exe" --Admin IsNotAutoStart IsNotTask
• "{Executed Malware File Path}\{Executed Malware File Name}.exe" --ForNetRes x5I74v4h003xJ0iyhUfHQ8W6o0RDSicmSfg72KVA 6se9RaIxXF9m70zWmx7nL3bVRp691w4SNY8UCir0 IsNotAutoStart IsNotTask
• "{Executed Malware File Path}\{Executed Malware File Name}.exe" --Service 1984 x5I74v4h003xJ0iyhUfHQ8W6o0RDSicmSfg72KVA 6se9RaIxXF9m70zWmx7nL3bVRp691w4SNY8UCir0
• "{Executed Malware File Path}\{Executed Malware File Name}.exe" --Service 2560 x5I74v4h003xJ0iyhUfHQ8W6o0RDSicmSfg72KVA 6se9RaIxXF9m70zWmx7nL3bVRp691w4SNY8UCir0

(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.)

It creates the following folders:

• %AppDataLocal%\{Hash of Machine GUID}

(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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• {1D6FC66E-D1F3-422C-8A53-C0BBCF3D900D}
• HFSMUTEX000000000001e86bG
• {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%\{Hash of Machine GUID}\{Malware File Name}.exe" --AutoStart

Other Details

This Ransomware does the following:

• Adds the following Scheduled Task:
  Task Name: Time Trigger Task
  Schedule: Starts at 1:20 PM on 11/1/2018 - after triggered repeat every 5 mins. Trigger expires at 5/2/2020 8:00 AM
  Task to be run: "%AppDataLocal%\{Hash of Machine GUID}\{Malware File Name}.exe"
• Connects to the URL to get the arguments needed for the "--Service" and "--ForNetRes" to perform it's routine:
  
  • http://{BLOCKED}nagets.ru/003/get.php?pid=07681C37D9C280E24A62211D2ECCD4F4
• It also closes the Windows Explorer.
• It accepts the following arguments to perform its routine:
  
  • --Admin: run the malware as admin
  • --AutoStart: Creates an Auto Start mechanism using registry keys to execute the malware.
  • --ForNetRes {Argumet from the URL} {Argument From the URL}
  • --Service {PID of the Parent Malware Running} {Argumet from the URL} {Argument From the URL}
  • IsAutoStart
  • IsNotAutoStart
  • IsTask
  • IsNotTask

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

• %Application Data%
• %AppDataLocal%
• %Desktop%
• %Windows%
• %Public%
• %ProgramData%\Microsoft\
• %ProgramData%\Package Cache\
• C:\PerfLogs\
• C:\$Recycle.Bin\
• C:\$WINDOWS.~BT\
• C:\dell\
• C:\Intel\
• C:\MSOCache\
• %Program Files% ; (for both 32 and 64 bit OS)
• C:\Games\
• C:\Windows.old\
• {Logical Drive Letter}\Users\%username%\AppData\Roaming\
• {Logical Drive Letter}\Users\%username%\AppData\Local\
• {Logical Drive Letter}\Windows\
• {Logical Drive Letter}\PerfLogs\
• {Logical Drive Letter}\ProgramData\Desktop\
• {Logical Drive Letter}\ProgramData\Microsoft\
• {Logical Drive Letter}\ProgramData\Package Cache\
• {Logical Drive Letter}\Users\Public\
• {Logical Drive Letter}\$Recycle.Bin\
• {Logical Drive Letter}\$WINDOWS.~BT\
• {Logical Drive Letter}\dell\
• {Logical Drive Letter}\Intel\
• {Logical Drive Letter}\MSOCache\
• {Logical Drive Letter}\Program Files\
• {Logical Drive Letter}\Program Files (x86)\
• {Logical Drive Letter}\Games\

(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.. %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.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista, 7, and 8.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.. %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 in Windows Vista, 7, and 8.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

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

• {File Name}.{File Extension}.INFOWAIT

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

• {Encrypted Directory}\!readme.txt