| ID | Technique | Tactic |
|---|---|---|
| T1566 | Phishing | Initial Access |
Detection: Zscaler Behavior Analysis Threat Blocked
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.
Search
1`zscaler_proxy` action=blocked threatname!="None" threatclass="Behavior Analysis"
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_behavior_analysis_threat_blocked_filter`
Data Source
No data sources specified for this detection.
Macros Used
| Name | Value |
|---|---|
| security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
| zscaler_behavior_analysis_threat_blocked_filter | search * |
zscaler_behavior_analysis_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
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
KillChainPhase.DELIVERY
NistCategory.DE_AE
Cis18Value.CIS_10
Axiom
GOLD SOUTHFIELD
INC Ransom
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 |
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.
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 Adware Behavior Analysis Threat from dest -[$dest$] on $src$ for user-[$user$]. | 8 | 10 | 80 |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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: 3