Kubernetes Nginx Ingress RFI

name: Kubernetes Nginx Ingress RFI
id: fc5531ae-62fd-4de6-9c36-b4afdae8ca95
version: 11
creation_date: '2021-08-23'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic detects remote file inclusion (RFI) attacks targeting Kubernetes Nginx ingress controllers. It leverages Kubernetes logs from the Nginx ingress controller, parsing fields such as `remote_addr`, `request`, and `url` to identify suspicious activity. This activity is significant because RFI attacks can allow attackers to execute arbitrary code or access sensitive files on the server. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or further compromise of the Kubernetes environment.
data_source: []
search: '`kubernetes_container_controller` | rex field=_raw "^(?<remote_addr>\S+)\s+-\s+-\s+\[(?<time_local>[^\]]*)\]\s\"(?<request>[^\"]*)\"\s(?<status>\S*)\s(?<body_bytes_sent>\S*)\s\"(?<http_referer>[^\"]*)\"\s\"(?<http_user_agent>[^\"]*)\"\s(?<request_length>\S*)\s(?<request_time>\S*)\s\[(?<proxy_upstream_name>[^\]]*)\]\s\[(?<proxy_alternative_upstream_name>[^\]]*)\]\s(?<upstream_addr>\S*)\s(?<upstream_response_length>\S*)\s(?<upstream_response_time>\S*)\s(?<upstream_status>\S*)\s(?<req_id>\S*)" | rex field=request "^(?<http_method>\S+)?\s(?<url>\S+)\s" | rex field=url "(?<dest_ip>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})" | search dest_ip=* | rename remote_addr AS src_ip, upstream_status as status, proxy_upstream_name as proxy | eval phase="operate" | eval severity="medium" | stats count min(_time) as firstTime max(_time) as lastTime by src_ip, dest_ip status, url, http_method, host, http_user_agent, proxy, phase, severity | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `kubernetes_nginx_ingress_rfi_filter`'
how_to_implement: You must ingest Kubernetes logs through Splunk Connect for Kubernetes.
known_false_positives: No false positives have been identified at this time.
references:
    - https://github.com/splunk/splunk-connect-for-kubernetes
    - https://www.invicti.com/blog/web-security/remote-file-inclusion-vulnerability/
finding:
    title: Remote File Inclusion Attack detected on $host$
    entity:
        field: host
        type: system
        score: 50
threat_objects:
    - field: src_ip
      type: ip_address
analytic_story:
    - Dev Sec Ops
asset_type: Kubernetes
mitre_attack_id:
    - T1212
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: network