Detectionmediumtest

Suspicious Curl File Upload - Linux

Detects a suspicious curl process start the adds a file to a web request

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Nasreddine Bencherchali (Nextron Systems), Cedric MAURUGEONCreated Thu Sep 15Updated Tue May 0200b90cc1-17ec-402c-96ad-3a8117d7a582linux

Log Source

LinuxProcess Creation

ProductLinux← raw: linux

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:
    selection_img:
        Image|endswith: '/curl'
    selection_cli:
        - CommandLine|contains:
              - ' --form' # Also covers the "--form-string"
              - ' --upload-file '
              - ' --data '
              - ' --data-' # For flags like: "--data-ascii", "--data-binary", "--data-raw", "--data-urlencode"
        - CommandLine|re: '\s-[FTd]\s' # We use regex to ensure a case sensitive argument detection
    filter_optional_localhost:
        CommandLine|contains:
            - '://localhost'
            - '://127.0.0.1'
    condition: all of selection_* and not 1 of filter_optional_*