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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.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-17
  • Author: Rod Soto, Gowthamaraj Rajendran, Splunk
  • ID: 289ad59f-8939-4331-b805-f2bd51d36fb8

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`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`

Macros

The SPL above uses the following Macros:

:information_source: zscaler_behavior_analysis_threat_blocked_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • action
  • threatname
  • deviceowner
  • user
  • urlcategory
  • url
  • dest
  • dest_ip
  • action

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
8.0 10 80 Potential Adware Behavior Analysis Threat from dest -[$dest$] on $src$ for user-[$user$].

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 2