Analysis

  • max time kernel
    149s
  • max time network
    148s
  • platform
    windows11-21h2_x64
  • resource
    win11-20260911-en
  • resource tags

    arch:x64arch:x86image:win11-20260911-enlocale:en-usos:windows11-21h2-x64systemwindows
  • submitted
    23/09/2026, 23:38

General

  • Target
    MasonClient.exe
  • Size 48KB
  • Sample260923-3m4zmsgc95
  • SHA256 b9cdd113799ba3b6f22bc5ed593a71a61f37429b14af020a2acbed2eab6686a8
  • MD5 SHA1 SHA512 SSDEEP TLSH

Malware Config

Extracted

Family
  • neptunerat

C2
  • h2ackercypranos-49474.portmap.host:49474

Attributes
  • filename

    USB.exe

  • group

    MasonGroup

  • key

    OWKlVlNZmydAbDUL

  • rat_name

    MasonRAT

Signatures

  • Family: NeptuneRAT, MasonRAT

    NeptuneRAT aka MasonRAT is a trojan written in C#.

  • Detects NeptuneRAT stealer 2 IoCs
  • Executes dropped EXE 4 IoCs
  • Enumerates physical storage devices 1 TTPs

    Attempts to interact with connected storage/optical drive(s).

  • Scheduled Task/Job: Scheduled Task 1 TTPs 1 IoCs

    Schtasks is often used by malware for persistence or to perform post-infection execution.

  • Suspicious use of AdjustPrivilegeToken 5 IoCs
  • Suspicious use of WriteProcessMemory 1 IoCs
  • Uses Task Scheduler COM API 1 TTPs

    The Task Scheduler COM API can be used to schedule applications to run on boot or at set times.

Processes

  • C:\Users\Admin\AppData\Local\Temp\MasonClient.exe
    "C:\Users\Admin\AppData\Local\Temp\MasonClient.exe"
    1⤵
    • Suspicious use of AdjustPrivilegeToken
    • Suspicious use of WriteProcessMemory
    PID:4128
    • C:\Windows\System32\schtasks.exe
      "C:\Windows\System32\schtasks.exe" /create /f /sc minute /mo 1 /tn "MasonClient" /tr "C:\Users\Admin\AppData\Roaming\MasonClient.exe"
      2⤵
      • Scheduled Task/Job: Scheduled Task
      PID:2996
  • C:\Users\Admin\AppData\Roaming\MasonClient.exe
    C:\Users\Admin\AppData\Roaming\MasonClient.exe
    1⤵
    • Executes dropped EXE
    • Suspicious use of AdjustPrivilegeToken
    PID:4068
  • C:\Users\Admin\AppData\Roaming\MasonClient.exe
    C:\Users\Admin\AppData\Roaming\MasonClient.exe
    1⤵
    • Executes dropped EXE
    • Suspicious use of AdjustPrivilegeToken
    PID:784
  • C:\Users\Admin\AppData\Roaming\MasonClient.exe
    C:\Users\Admin\AppData\Roaming\MasonClient.exe
    1⤵
    • Executes dropped EXE
    • Suspicious use of AdjustPrivilegeToken
    PID:1704
  • C:\Users\Admin\AppData\Roaming\MasonClient.exe
    C:\Users\Admin\AppData\Roaming\MasonClient.exe
    1⤵
    • Executes dropped EXE
    • Suspicious use of AdjustPrivilegeToken
    PID:4588

Network

        MITRE ATT&CK Enterprise v16

        Replay Monitor

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        Downloads

        MasonClient.exe.log

        • Path C:\Users\Admin\AppData\Local\Microsoft\CLR_v4.0\UsageLogs\MasonClient.exe.log
        • Size 654B
        • SHA256 e31b18f21621d9983bfdf1ea3e53884a9d58b8ffd79e0e5790da6f3a81a8b9d3
        • MD5 SHA1 SHA512 TLSH

        MasonClient.exe

        • Path C:\Users\Admin\AppData\Roaming\MasonClient.exe
        • Size 48KB
        • SHA256 b9cdd113799ba3b6f22bc5ed593a71a61f37429b14af020a2acbed2eab6686a8
        • MD5 SHA1 SHA512 SSDEEP TLSH

        memory/4128-0-0x00000000002E0000-0x00000000002F2000-memory.dmp

        memory/4128-2-0x00000000023C0000-0x00000000023D0000-memory.dmp

        memory/4128-8-0x00000000023C0000-0x00000000023D0000-memory.dmp