Analysis

  • max time kernel
    94s
  • max time network
    129s
  • platform
    windows10-2004_x64
  • resource
    win10v2004-20250217-en
  • resource tags

    arch:x64arch:x86image:win10v2004-20250217-enlocale:en-usos:windows10-2004-x64system
  • submitted
    19/02/2025, 03:50

General

  • Target
    YashmaClients.exe
  • Size 129KB
  • Sample250219-ed3s8awnew
  • SHA256 a83e19610aa006d4789bb38e18b609538befb16a1df30e1205e0c38aeda089e4
  • MD5 SHA1 SHA512 SSDEEP

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) 64 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:3828
    • 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:1956
      • 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:2272
        • C:\Windows\system32\vssadmin.exe
          vssadmin delete shadows /all /quiet
          4⤵
          • Interacts with shadow copies
          PID:2796
        • C:\Windows\System32\Wbem\WMIC.exe
          wmic shadowcopy delete
          4⤵
          • Suspicious use of AdjustPrivilegeToken
          PID:2284
      • 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:2704
        • C:\Windows\system32\bcdedit.exe
          bcdedit /set {default} bootstatuspolicy ignoreallfailures
          4⤵
          • Modifies boot configuration data using bcdedit
          PID:4820
        • C:\Windows\system32\bcdedit.exe
          bcdedit /set {default} recoveryenabled no
          4⤵
          • Modifies boot configuration data using bcdedit
          PID:3212
      • C:\Windows\System32\cmd.exe
        "C:\Windows\System32\cmd.exe" /C wbadmin delete catalog -quiet
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:4344
        • C:\Windows\system32\wbadmin.exe
          wbadmin delete catalog -quiet
          4⤵
          • Deletes backup catalog
          PID:2128
      • 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:1932
  • C:\Windows\system32\vssvc.exe
    C:\Windows\system32\vssvc.exe
    1⤵
    • Suspicious use of AdjustPrivilegeToken
    PID:2060
  • C:\Windows\system32\wbengine.exe
    "C:\Windows\system32\wbengine.exe"
    1⤵
    • Suspicious use of AdjustPrivilegeToken
    PID:4192
  • C:\Windows\System32\vdsldr.exe
    C:\Windows\System32\vdsldr.exe -Embedding
    1⤵
      PID:2512
    • C:\Windows\System32\vds.exe
      C:\Windows\System32\vds.exe
      1⤵
      • Checks SCSI registry key(s)
      PID:4888

    Network

          MITRE ATT&CK Enterprise v15

          Replay Monitor

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          Downloads

          read_it.txt

          • Path C:\ProgramData\Adobe\Setup\{AC76BA86-7AD7-1033-7B44-AC0F074E4100}\read_it.txt
          • Size 342B
          • SHA256 02132ce5b64b9bbbf77f1e6015569583f015039abb8f2ab021c9db1ae5116383
          • MD5 SHA1 SHA512

          YashmaClients.exe.log

          • Path C:\Users\Admin\AppData\Local\Microsoft\CLR_v4.0\UsageLogs\YashmaClients.exe.log
          • Size 1KB
          • SHA256 ee954c5d8156fd8890e582c716e5758ed9b33721258f10e758bdc31ccbcb1924
          • MD5 SHA1 SHA512

          svchost.exe

          • Path C:\Users\Admin\AppData\Roaming\svchost.exe
          • Size 129KB
          • SHA256 a83e19610aa006d4789bb38e18b609538befb16a1df30e1205e0c38aeda089e4
          • MD5 SHA1 SHA512 SSDEEP

          Magnify.lnk

          • Path C:\Users\Default\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Accessibility\Magnify.lnk
          • Size 1B
          • SHA256 8a8de823d5ed3e12746a62ef169bcf372be0ca44f0a1236abc35df05d96928e1
          • MD5 SHA1 SHA512

          memory/1956-16-0x00007FF8AA760000-0x00007FF8AB221000-memory.dmp

          memory/1956-1192-0x00007FF8AA760000-0x00007FF8AB221000-memory.dmp

          memory/3828-0-0x00007FF8AA763000-0x00007FF8AA765000-memory.dmp

          memory/3828-1-0x0000000000C80000-0x0000000000CA6000-memory.dmp

          memory/3828-2-0x00007FF8AA760000-0x00007FF8AB221000-memory.dmp

          memory/3828-15-0x00007FF8AA760000-0x00007FF8AB221000-memory.dmp