Analysis

  • max time kernel
    124s
  • max time network
    147s
  • platform
    windows10_x64
  • resource
    win10v200430
  • submitted
    08/07/2020, 15:39

General

  • Target
    DocumentPreview.exe
  • Size 146KB
  • Sample200708-vb9b17td3a
  • SHA256 e212e5bc428a0bca4615205f07c10d4e57dc881a2f32a9b8aeec040169435aa1
  • MD5 SHA1 SHA512
Score
10/10

Malware Config

Extracted

Family
  • buer

C2
  • https://162.244.81.87/

  • http://162.244.81.87:8080/

Signatures

  • Buer

    Buer is a new modular loader first seen in August 2019.

  • Modifies WinLogon for persistence 2 TTPs 1 IoCs
  • Buer Loader 1 IoCs

    Detects Buer loader in memory or disk.

  • Executes dropped EXE 1 IoCs
  • Deletes itself 1 IoCs
  • Enumerates connected drives 3 TTPs 24 IoCs

    Attempts to read the root path of hard drives other than the default C: drive.

  • Enumerates physical storage devices 1 TTPs

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

  • Program crash 1 IoCs
  • Suspicious behavior: EnumeratesProcesses 15 IoCs
  • Suspicious use of AdjustPrivilegeToken 3 IoCs
  • Suspicious use of WriteProcessMemory 16 IoCs

Processes

  • C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe
    "C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe"
    1⤵
    • Suspicious use of WriteProcessMemory
    PID:3908
    • C:\ProgramData\489b1a91ca40d281ca53\gennt.exe
      C:\ProgramData\489b1a91ca40d281ca53\gennt.exe "C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe" ensgJJ
      2⤵
      • Modifies WinLogon for persistence
      • Executes dropped EXE
      • Deletes itself
      • Enumerates connected drives
      • Suspicious behavior: EnumeratesProcesses
      • Suspicious use of WriteProcessMemory
      PID:2200
      • C:\Windows\SysWOW64\secinit.exe
        C:\ProgramData\489b1a91ca40d281ca53\gennt.exe
        3⤵
          PID:2864
          • C:\Windows\SysWOW64\WerFault.exe
            C:\Windows\SysWOW64\WerFault.exe -u -p 2864 -s 356
            4⤵
            • Program crash
            • Suspicious behavior: EnumeratesProcesses
            • Suspicious use of AdjustPrivilegeToken
            PID:3916
        • C:\Windows\SysWOW64\cmd.exe
          "C:\Windows\System32\cmd.exe" powershell.exe -Command "& {Add-MpPreference -ExclusionPath C:\ProgramData\489b1a91ca40d281ca53}"
          3⤵
            PID:3992

      Network

            MITRE ATT&CK Enterprise v6

            Replay Monitor

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            Downloads

            memory/3908-0-0x00000000001E0000-0x00000000001EC000-memory.dmp

            memory/3916-6-0x00000000043D0000-0x00000000043D1000-memory.dmp

            memory/3916-7-0x00000000043D0000-0x00000000043D1000-memory.dmp

            memory/3916-14-0x0000000004A20000-0x0000000004A21000-memory.dmp