security_content/detections/web/http_scripting_tool_user_agent.yml at develop · jwindley/security_content · GitHub

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name: HTTP Scripting Tool User Agent
id: 04430b4e-5ca8-4e88-98b5-d6bcf54f8393
version: 1
date: '2025-10-09'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: This Splunk query analyzes web access logs to identify and categorize
  non-browser user agents, detecting various types of security tools, scripting languages,
  automation frameworks, and suspicious patterns. This activity can signify malicious actors
  attempting to interact with web endpoints in non-standard ways.
data_source:
- Nginx Access
search: '`nginx_access_logs`
  | eval http_user_agent = lower(http_user_agent)
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `drop_dm_object_name(Web)`
  | lookup scripting_tools_user_agents tool_user_agent AS http_user_agent OUTPUT tool
  | where isnotnull(tool)
  | rename dest_ip as dest
  | stats count min(firstTime) as first_seen max(lastTime) as last_seen values(tool) as tool
  by http_user_agent dest src_ip status
  | `http_scripting_tool_user_agent_filter`'
how_to_implement: This analytic necessitates the collection of web data, which can
  be achieved through Splunk Stream or by utilizing the Splunk Add-on for Apache Web
  Server. No additional configuration is required for this analytic.
known_false_positives: False positives may be present if the activity is part of diagnostics
  or testing. Filter as needed.
references:
  - https://portswigger.net/web-security/request-smuggling#what-is-http-request-smuggling
  - https://portswigger.net/research/http1-must-die
  - https://www.vaadata.com/blog/what-is-http-request-smuggling-exploitations-and-security-best-practices/
  - https://www.securityweek.com/new-http-request-smuggling-attacks-impacted-cdns-major-orgs-millions-of-websites/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/web/proxy_generic/proxy_ua_hacktool.yml
  - https://help.aikido.dev/zen-firewall/miscellaneous/bot-protection-details
drilldown_searches:
- name: View the detection results for - "$dest$"
  search: '%original_detection_search% | search  dest = "$dest$"'
  earliest_offset: $info_min_time$
  latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$dest$"
  search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$")
    starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime
    values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories)
    as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic)
    as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`'
  earliest_offset: $info_min_time$
  latest_offset: $info_max_time$
rba:
  message: Known scripting tool was used against a web request.
    The source IP is $src_ip$ and the destination is $dest$.
  risk_objects:
  - field: dest
    type: system
    score: 31
  threat_objects:
  - field: src_ip
    type: ip_address
tags:
  analytic_story:
  - HTTP Request Smuggling
  - Suspicious User Agents
  asset_type: Network
  mitre_attack_id:
  - T1071.001
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  security_domain: network
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1190/request_smuggling/nginx_scripting_tools.log
    source: nginx:plus:kv
    sourcetype: nginx:plus:kv