ID | Technique | Tactic |
---|---|---|
T1566 | Phishing | Initial Access |
Detection: Zscaler Phishing Activity Threat Blocked
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.
Search
1`zscaler_proxy` action=blocked threatname="HTML.Phish*"
2| stats count min(_time) as firstTime max(_time) as lastTime by action deviceowner user threatname url src dest
3| `security_content_ctime(firstTime)`
4| `security_content_ctime(lastTime)`
5| `zscaler_phishing_activity_threat_blocked_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
N/A | N/A | N/A | N/A | N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
zscaler_phishing_activity_threat_blocked_filter | search * |
zscaler_phishing_activity_threat_blocked_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Potential Phishing Activity from dest -[$dest$] on $src$ for user-[$user$]. | 16 | 20 | 80 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | zscaler |
zscalernss-web |
Integration | ✅ Passing | Dataset | zscaler |
zscalernss-web |
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: GitHub | Version: 2