Elastic medium stable eql

Script Interpreter Connection to Non-Standard Port

Detects the execution of a script interpreter followed by an outbound network connection to a raw IP address on a non-standard port. Many initial access scripts and malware implants connect directly to C2 or payload servers using non-standard ports to avoid detection.

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Detection Logic

sequence by process.entity_id with maxspan=1m
  [process where host.os.type == "macos" and event.type == "start" and event.action == "exec" and 
    (process.name like~ "python*" or process.name in ("node", "ruby")) and 
    process.args_count == 2]
  [network where host.os.type == "macos" and event.type == "start" and 
    (process.name like~ "python*" or process.name in ("node", "ruby")) and 
    destination.domain == null and 
    not destination.port in (443, 80, 53, 22, 25, 587, 465, 8080, 8089, 8200, 9200) and 
    destination.port < 49152 and
    not cidrmatch(destination.ip, "240.0.0.0/4", "233.252.0.0/24", "224.0.0.0/4", "198.19.0.0/16", 
                  "192.18.0.0/15", "192.0.0.0/24", "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", 
                  "172.16.0.0/12", "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", 
                  "192.168.0.0/16", "192.88.99.0/24", "100.64.0.0/10", "192.175.48.0/24", 
                  "198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "::1", "FE80::/10", "FF00::/8")]

Field Validations

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