Detection rules › Splunk

Zscaler Legal Liability Threat Blocked

Status
production
Severity
low
Group by
action, dest, deviceowner, src, url, urlcategory, user
Author
Rod Soto, Gowthamaraj Rajendran, Splunk
Source
github.com/splunk/security_content

The following analytic identifies significant legal liability threats blocked by the Zscaler web proxy. It uses web proxy logs to track destinations, device owners, users, URL categories, and actions associated with legal liability. By leveraging statistics on unique fields, it ensures a precise focus on these threats. This activity is significant for SOC as it helps enforce legal compliance and risk management. If confirmed malicious, it could indicate attempts to access legally sensitive or restricted content, potentially leading to legal repercussions and compliance violations.

Known false positives

  • False positives are limited to Zscaler configuration.

MITRE ATT&CK coverage

TacticTechniques
Initial Access

Rule body

name: Zscaler Legal Liability Threat Blocked
id: bbf55ebf-c416-4f62-94d9-4064f2a28014
version: 9
creation_date: '2024-04-17'
modification_date: '2026-05-13'
author: Rod Soto, Gowthamaraj Rajendran, Splunk
status: production
type: Anomaly
description: The following analytic identifies significant legal liability threats blocked by the Zscaler web proxy. It uses web proxy logs to track destinations, device owners, users, URL categories, and actions associated with legal liability. By leveraging statistics on unique fields, it ensures a precise focus on these threats. This activity is significant for SOC as it helps enforce legal compliance and risk management. If confirmed malicious, it could indicate attempts to access legally sensitive or restricted content, potentially leading to legal repercussions and compliance violations.
data_source: []
search: |-
    `zscaler_proxy` urlclass="Legal Liability"
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY action deviceowner user
           urlcategory url src
           dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | dedup urlcategory
      | `zscaler_legal_liability_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 Zscaler configuration.
references:
    - https://help.zscaler.com/zia/nss-feed-output-format-web-logs
intermediate_findings:
    entities:
        - field: src
          type: system
          score: 20
          message: Potential Legal Liability Threat from dest -[$dest$] on $src$ for user-[$user$].
        - field: user
          type: user
          score: 20
          message: Potential Legal Liability Threat from dest -[$dest$] on $src$ for user-[$user$].
threat_objects:
    - field: url
      type: url
analytic_story:
    - Zscaler Browser Proxy Threats
asset_type: Web Server
mitre_attack_id:
    - T1566
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: web
security_domain: threat

Stages and Predicates

Stage 1: search

`zscaler_proxy` urlclass="Legal Liability"

Stage 2: stats

| stats count min(_time) as firstTime max(_time) as lastTime
    BY action deviceowner user
       urlcategory url src
       dest

Stage 3: search

| `security_content_ctime(firstTime)`

Stage 4: search

| `security_content_ctime(lastTime)`

Stage 5: dedup

| dedup urlcategory

Stage 6: search

| `zscaler_legal_liability_threat_blocked_filter`

Indicators

These rows show field, operator, and value matches.