Detectionmediumtest

Indirect Command Execution From Script File Via Bash.EXE

Detects execution of Microsoft bash launcher without any flags to execute the content of a bash script directly. This can be used to potentially bypass defenses and execute Linux or Windows-based binaries directly via bash.

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Launch
Nasreddine Bencherchali (Nextron Systems)Created Tue Aug 152d22a514-e024-4428-9dba-41505bd63a5bwindows
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic
Detection Logic5 selectors
detection:
    selection:
        - Image|endswith:
              - ':\Windows\System32\bash.exe'
              - ':\Windows\SysWOW64\bash.exe'
        - OriginalFileName: 'Bash.exe'
    filter_main_cli_flag:
        CommandLine|contains:
            # Note: we're not interested in flags being passed first
            - 'bash.exe -'
            - 'bash -'
    filter_main_no_cli:
        CommandLine: null
    filter_main_empty:
        CommandLine: ''
    filter_main_no_flag:
        CommandLine:
            - 'bash.exe'
            - 'bash'
    condition: selection and not 1 of filter_main_*
False Positives
Unknown

False positive likelihood has not been assessed. Additional context may be needed during triage.