port_proxy_forwarding_T1090_cisa_report

rule port_proxy_forwarding_T1090_cisa_report {

  meta:
    author = "Google Cloud Security"
    description = "Detects port forwarding being enabled using netsh command and registry settings created or modified in support of portproxy v4tov4"
    rule_id = "mr_4c6f2d66-ed6f-4dda-bd2f-7c545898468b"
    rule_name = "MITRE ATT&CK T1090 Port Proxy Forwarding CISA Report"
    type = "hunt"
    platform = "Windows"
    data_source = "microsoft sysmon, windows event log"
    tactic = "TA0011"
    technique = "T1090"
    reference = "https://media.defense.gov/2023/May/24/2003229517/-1/-1/0/CSA_Living_off_the_Land.PDF"
    severity = "Low"
    priority = "Low"

  events:
    (
        $process.metadata.event_type = "PROCESS_LAUNCH" and

        // cisa report referenced cmd /c in their report throughout, can filter this in/out for tuning as needed
        re.regex($process.target.process.command_line, `(|cmd.*/c).*netsh.*interface.*portproxy.*add.*v4tov4`) nocase
        // For greater precision to align with the report, comment out the above line and uncomment the below line to incorporate exact ports referenced
        //re.regex($process.target.process.command_line, `(|cmd.*/c).*netsh.*interface.*portproxy.*add.*v4tov4.*port\=(9999|50100).*port\=(8443|1433)`) nocase
    )
    or
    (
        // Looks for the actual registry creation or modification that would accompany portproxy command executing
        (
        $process.metadata.event_type = "REGISTRY_CREATION" or
        $process.metadata.event_type = "REGISTRY_MODIFICATION"
        ) and
        $process.target.registry.registry_key = "HKLM\\System\\CurrentControlSet\\Services\\PortProxy\\v4tov4"
    )

    $process.principal.hostname = $hostname

  match:
    $hostname over 5m

  outcome:
    $risk_score = 35
    $event_count = count_distinct($process.metadata.id)
    // added to populate alert graph with additional context
    // Commented out principal.hostname because it is already represented in graph as match variable. If match changes, can uncomment to add to results
    //$principal_hostname = array_distinct($process.principal.hostname)
    $principal_process_pid = array_distinct($process.principal.process.pid)
    $principal_process_command_line = array_distinct($process.principal.process.command_line)
    $principal_process_file_sha256 = array_distinct($process.principal.process.file.sha256)
    $principal_process_file_full_path = array_distinct($process.principal.process.file.full_path)
    $principal_process_product_specific_process_id = array_distinct($process.principal.process.product_specific_process_id)
    $principal_process_parent_process_product_specific_process_id = array_distinct($process.principal.process.parent_process.product_specific_process_id)
    $target_process_pid = array_distinct($process.target.process.pid)
    $target_process_command_line = array_distinct($process.target.process.command_line)
    $target_process_file_sha256 = array_distinct($process.target.process.file.sha256)
    $target_process_file_full_path = array_distinct($process.target.process.file.full_path)
    $target_process_product_specific_process_id = array_distinct($process.target.process.product_specific_process_id)
    $principal_user_userid = array_distinct($process.principal.user.userid)

  condition:
    $process
}