Zscaler Behavior Analysis Threat Blocked

name: Zscaler Behavior Analysis Threat Blocked
id: 289ad59f-8939-4331-b805-f2bd51d36fb8
version: 9
date: '2026-04-15'
author: Rod Soto, Gowthamaraj Rajendran, Splunk
status: production
type: Anomaly
data_source: []
description: The following analytic identifies threats blocked by the Zscaler proxy based on behavior analysis. It leverages web proxy logs to detect entries where actions are blocked and threat names and classes are specified. This detection is significant as it highlights potential malicious activities that were intercepted by Zscaler's behavior analysis, providing early indicators of threats. If confirmed malicious, these blocked threats could indicate attempted breaches or malware infections, helping security teams to understand and mitigate potential risks in their environment.
search: |-
    `zscaler_proxy` action=blocked threatname!="None" threatclass="Behavior Analysis"
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY action deviceowner user
           threatname url src
           dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `zscaler_behavior_analysis_threat_blocked_filter`
how_to_implement: You must install the latest version of Zscaler Add-on from Splunkbase. You must be ingesting Zscaler events into your Splunk environment through an ingester. This analytic was written to be used with the "zscalernss-web" sourcetype leveraging the Zscaler proxy data. This enables the integration with Splunk Enterprise Security. Security teams are encouraged to adjust the detection parameters, ensuring the detection is tailored to their specific environment.
known_false_positives: False positives are limited to Zscalar configuration.
references:
    - https://help.zscaler.com/zia/nss-feed-output-format-web-logs
drilldown_searches:
    - name: View the detection results for - "$src$" and "$user$"
      search: '%original_detection_search% | search  src = "$src$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$src$" and "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$", "$user$") | 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: 7d
      latest_offset: "0"
rba:
    message: Potential Adware Behavior Analysis Threat from dest -[$dest$] on $src$ for user-[$user$].
    risk_objects:
        - field: src
          type: system
          score: 20
        - field: user
          type: user
          score: 20
    threat_objects:
        - field: url
          type: url
tags:
    analytic_story:
        - Zscaler Browser Proxy Threats
    asset_type: Web Server
    mitre_attack_id:
        - T1566
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: threat
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566/zscalar_web_proxy/zscalar_web_proxy.json
          source: zscaler
          sourcetype: zscalernss-web