Resubmissions

19-02-2025 03:41

250219-d8y8vawnam 10

Analysis

  • max time kernel
    45s
  • max time network
    33s
  • platform
    windows10-ltsc 2021_x64
  • resource
    win10ltsc2021-20250217-en
  • resource tags

    arch:x64arch:x86image:win10ltsc2021-20250217-enlocale:en-usos:windows10-ltsc 2021-x64system
  • submitted
    21-02-2025 04:30

General

  • Target

    YashmaClients.exe

  • Size

    129KB

  • MD5

    15fba1967c6bcd09520811dfe34a159b

  • SHA1

    dec383511b8f764f3222798586ee22f0fda0331c

  • SHA256

    a83e19610aa006d4789bb38e18b609538befb16a1df30e1205e0c38aeda089e4

  • SHA512

    f2990e7c548f0bb18e84aeff62a38ce5d97046b44313dfda948d51efe4eac7c855b71437b57cb2e9f48453a27570559c3d6ab8349be1fdbaac44b2ef79f9dc59

  • SSDEEP

    768:x7zxAmU2NJ1KQxJPho9aT3e82hQfMCwRhOF15utoS:xND3x7Pq9m3ZsA/wCFLS

Malware Config

Signatures

  • Chaos

    Ransomware family first seen in June 2021.

  • Chaos Ransomware 2 IoCs
  • Chaos family
  • Deletes shadow copies 3 TTPs

    Ransomware often targets backup files to inhibit system recovery.

  • Modifies boot configuration data using bcdedit 1 TTPs 2 IoCs
  • Deletes backup catalog 3 TTPs 1 IoCs

    Uses wbadmin.exe to inhibit system recovery.

  • Disables Task Manager via registry modification
  • Checks computer location settings 2 TTPs 2 IoCs

    Looks up country code configured in the registry, likely geofence.

  • Drops startup file 2 IoCs
  • Executes dropped EXE 1 IoCs
  • Reads user/profile data of web browsers 3 TTPs

    Infostealers often target stored browser data, which can include saved credentials etc.

  • Adds Run key to start application 2 TTPs 1 IoCs
  • Drops desktop.ini file(s) 63 IoCs
  • Enumerates physical storage devices 1 TTPs

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

  • Checks SCSI registry key(s) 3 TTPs 4 IoCs

    SCSI information is often read in order to detect sandboxing environments.

  • Interacts with shadow copies 3 TTPs 1 IoCs

    Shadow copies are often targeted by ransomware to inhibit system recovery.

  • Modifies registry class 1 IoCs
  • Opens file in notepad (likely ransom note) 1 IoCs
  • Suspicious behavior: AddClipboardFormatListener 2 IoCs
  • Suspicious behavior: EnumeratesProcesses 44 IoCs
  • Suspicious use of AdjustPrivilegeToken 50 IoCs
  • Suspicious use of WriteProcessMemory 20 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.

  • Uses Volume Shadow Copy service COM API

    The Volume Shadow Copy service is used to manage backups/snapshots.

Processes

  • C:\Users\Admin\AppData\Local\Temp\YashmaClients.exe
    "C:\Users\Admin\AppData\Local\Temp\YashmaClients.exe"
    1⤵
    • Checks computer location settings
    • Suspicious behavior: AddClipboardFormatListener
    • Suspicious behavior: EnumeratesProcesses
    • Suspicious use of AdjustPrivilegeToken
    • Suspicious use of WriteProcessMemory
    PID:4760
    • C:\Users\Admin\AppData\Roaming\svchost.exe
      "C:\Users\Admin\AppData\Roaming\svchost.exe"
      2⤵
      • Checks computer location settings
      • Drops startup file
      • Executes dropped EXE
      • Adds Run key to start application
      • Drops desktop.ini file(s)
      • Modifies registry class
      • Suspicious behavior: AddClipboardFormatListener
      • Suspicious behavior: EnumeratesProcesses
      • Suspicious use of AdjustPrivilegeToken
      • Suspicious use of WriteProcessMemory
      PID:2100
      • C:\Windows\System32\cmd.exe
        "C:\Windows\System32\cmd.exe" /C vssadmin delete shadows /all /quiet & wmic shadowcopy delete
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:3732
        • C:\Windows\system32\vssadmin.exe
          vssadmin delete shadows /all /quiet
          4⤵
          • Interacts with shadow copies
          PID:3384
        • C:\Windows\System32\Wbem\WMIC.exe
          wmic shadowcopy delete
          4⤵
          • Suspicious behavior: EnumeratesProcesses
          • Suspicious use of AdjustPrivilegeToken
          PID:2652
      • C:\Windows\System32\cmd.exe
        "C:\Windows\System32\cmd.exe" /C bcdedit /set {default} bootstatuspolicy ignoreallfailures & bcdedit /set {default} recoveryenabled no
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:1992
        • C:\Windows\system32\bcdedit.exe
          bcdedit /set {default} bootstatuspolicy ignoreallfailures
          4⤵
          • Modifies boot configuration data using bcdedit
          PID:1000
        • C:\Windows\system32\bcdedit.exe
          bcdedit /set {default} recoveryenabled no
          4⤵
          • Modifies boot configuration data using bcdedit
          PID:3096
      • C:\Windows\System32\cmd.exe
        "C:\Windows\System32\cmd.exe" /C wbadmin delete catalog -quiet
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:324
        • C:\Windows\system32\wbadmin.exe
          wbadmin delete catalog -quiet
          4⤵
          • Deletes backup catalog
          PID:636
      • C:\Windows\system32\NOTEPAD.EXE
        "C:\Windows\system32\NOTEPAD.EXE" C:\Users\Admin\AppData\Roaming\read_it.txt
        3⤵
        • Opens file in notepad (likely ransom note)
        PID:1096
  • C:\Windows\system32\vssvc.exe
    C:\Windows\system32\vssvc.exe
    1⤵
    • Suspicious use of AdjustPrivilegeToken
    PID:3272
  • C:\Windows\system32\wbengine.exe
    "C:\Windows\system32\wbengine.exe"
    1⤵
    • Suspicious use of AdjustPrivilegeToken
    PID:1480
  • C:\Windows\System32\vdsldr.exe
    C:\Windows\System32\vdsldr.exe -Embedding
    1⤵
      PID:800
    • C:\Windows\System32\vds.exe
      C:\Windows\System32\vds.exe
      1⤵
      • Checks SCSI registry key(s)
      PID:240
    • C:\Windows\system32\taskmgr.exe
      "C:\Windows\system32\taskmgr.exe" /4
      1⤵
        PID:4512
      • C:\Windows\system32\taskmgr.exe
        "C:\Windows\system32\taskmgr.exe" /4
        1⤵
          PID:2916

        Network

        MITRE ATT&CK Enterprise v15

        Replay Monitor

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        Downloads

        • C:\Users\Admin\AppData\Local\Microsoft\CLR_v4.0\UsageLogs\YashmaClients.exe.log

          Filesize

          1KB

          MD5

          b08c36ce99a5ed11891ef6fc6d8647e9

          SHA1

          db95af417857221948eb1882e60f98ab2914bf1d

          SHA256

          cc9248a177495f45ec70b86c34fc5746c56730af36ace98ac7eb365dbafda674

          SHA512

          07e62581eace395b0a9699d727761648103180c21155d84ea09140f9e1c9690705c419118545aa67a564334bbde32710225fe3aa92b0b4b4210cb91f0058b1ea

        • C:\Users\Admin\AppData\Local\read_it.txt

          Filesize

          342B

          MD5

          ee3b113d32ed8c4ee76443d3b81a72d3

          SHA1

          4042e1a579366b7c62ea5e75b7eff031b408d7bd

          SHA256

          02132ce5b64b9bbbf77f1e6015569583f015039abb8f2ab021c9db1ae5116383

          SHA512

          a2c00d94871d6842853ac42eb7c84c533dac1f7b875b4f4911e1298363cf703a85f64fb398bd760b51c819094f7db0047000660f0fd54ec61359a998ba5fd74b

        • C:\Users\Admin\AppData\Roaming\svchost.exe

          Filesize

          129KB

          MD5

          15fba1967c6bcd09520811dfe34a159b

          SHA1

          dec383511b8f764f3222798586ee22f0fda0331c

          SHA256

          a83e19610aa006d4789bb38e18b609538befb16a1df30e1205e0c38aeda089e4

          SHA512

          f2990e7c548f0bb18e84aeff62a38ce5d97046b44313dfda948d51efe4eac7c855b71437b57cb2e9f48453a27570559c3d6ab8349be1fdbaac44b2ef79f9dc59

        • C:\Users\Admin\Desktop\ClearSend.mht

          Filesize

          1B

          MD5

          d1457b72c3fb323a2671125aef3eab5d

          SHA1

          5bab61eb53176449e25c2c82f172b82cb13ffb9d

          SHA256

          8a8de823d5ed3e12746a62ef169bcf372be0ca44f0a1236abc35df05d96928e1

          SHA512

          ca63c07ad35d8c9fb0c92d6146759b122d4ec5d3f67ebe2f30ddb69f9e6c9fd3bf31a5e408b08f1d4d9cd68120cced9e57f010bef3cde97653fed5470da7d1a0

        • memory/2100-19-0x00007FFEF7190000-0x00007FFEF7C52000-memory.dmp

          Filesize

          10.8MB

        • memory/2100-1050-0x00007FFEF7190000-0x00007FFEF7C52000-memory.dmp

          Filesize

          10.8MB

        • memory/4760-0-0x00007FFEF7193000-0x00007FFEF7195000-memory.dmp

          Filesize

          8KB

        • memory/4760-1-0x0000000000F60000-0x0000000000F86000-memory.dmp

          Filesize

          152KB

        • memory/4760-2-0x00007FFEF7190000-0x00007FFEF7C52000-memory.dmp

          Filesize

          10.8MB

        • memory/4760-18-0x00007FFEF7190000-0x00007FFEF7C52000-memory.dmp

          Filesize

          10.8MB