Detection rules › Splunk
Zscaler Exploit Threat Blocked
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.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566 Phishing |
Rule body splunk
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
Stages and Predicates
Stage 1: search
`zscaler_proxy` action=blocked threatname=*exploit*
Stage 2: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY user threatname src
hostname fileclass filename
url dest
Stage 3: search
| `security_content_ctime(firstTime)`
Stage 4: search
| `security_content_ctime(lastTime)`
Stage 5: search
| `zscaler_exploit_threat_blocked_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
action | eq |
|
sourcetype | eq |
|
threatname | eq |
|