Zscaler Phishing Activity Threat Blocked

name: Zscaler Phishing Activity Threat Blocked
id: 68d3e2c1-e97f-4310-b080-dea180b48aa9
version: 10
creation_date: '2024-04-17'
modification_date: '2026-05-13'
author: Gowthamaraj Rajendran, Rod Soto, Splunk
status: production
type: Anomaly
description: The following analytic identifies potential phishing attempts blocked by Zscaler within a network. It leverages web proxy logs to detect actions tagged as HTML.Phish. The detection method involves analyzing critical data points such as user, threat name, URL, and hostname. This activity is significant for a SOC as it serves as an early warning system for phishing threats, enabling prompt investigation and mitigation. If confirmed malicious, this activity could indicate an attempt to deceive users into divulging sensitive information, potentially leading to data breaches or credential theft.
data_source: []
search: |-
    `zscaler_proxy` action=blocked threatname="HTML.Phish*"
      | 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_phishing_activity_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
intermediate_findings:
    entities:
        - field: src
          type: system
          score: 20
          message: Potential Phishing Activity from dest -[$dest$] on $src$ for user-[$user$].
        - field: user
          type: user
          score: 20
          message: Potential Phishing Activity from dest -[$dest$] on $src$ for user-[$user$].
threat_objects:
    - field: url
      type: url
analytic_story:
    - Zscaler Browser Proxy Threats
    - Hellcat Ransomware
asset_type: Web Server
mitre_attack_id:
    - T1566
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: web
security_domain: threat