Zscaler Exploit Threat Blocked

Description

The following analytic identifies potential exploit attempts involving command and script interpreters blocked by Zscaler. It leverages web proxy logs to detect incidents where actions are blocked due to exploit references. The detection compiles statistics by user, threat name, URL, hostname, file class, and filename. This activity is significant as it helps identify and mitigate exploit attempts, which are critical for maintaining security. If confirmed malicious, such activity could lead to unauthorized code execution, privilege escalation, or persistent access within the environment, posing a severe threat to organizational security.

Query · spl

`zscaler_proxy` action=blocked threatname=*exploit*
  | stats count min(_time) as firstTime max(_time) as lastTime
    BY user threatname src
       hostname fileclass filename
       url dest
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `zscaler_exploit_threat_blocked_filter`

Implementation guide

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.

Analyst notes

Known false positives: False positives are limited to Zscaler configuration.

Raw source Zscaler Exploit Threat Blocked · SPL
Esc
Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Zscaler Exploit Threat Blocked
id: 94665d8c-b841-4ff4-acb4-34d613e2cbfe
version: 10
creation_date: '2024-04-17'
modification_date: '2026-05-13'
author: Rod Soto, Gowthamaraj Rajendran, Splunk
status: production
type: TTP
description: The following analytic identifies potential exploit attempts involving command and script interpreters blocked by Zscaler. It leverages web proxy logs to detect incidents where actions are blocked due to exploit references. The detection compiles statistics by user, threat name, URL, hostname, file class, and filename. This activity is significant as it helps identify and mitigate exploit attempts, which are critical for maintaining security. If confirmed malicious, such activity could lead to unauthorized code execution, privilege escalation, or persistent access within the environment, posing a severe threat to organizational security.
data_source: []
search: |-
    `zscaler_proxy` action=blocked threatname=*exploit*
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY user threatname src
           hostname fileclass filename
           url dest
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `zscaler_exploit_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
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"
finding:
    title: Potential Exploit Threat from dest -[$dest$] on $src$ for user-[$user$].
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: src
          type: system
          score: 50
          message: Potential Exploit 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
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
      test_type: unit

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