Risk-based Authentication

Risk-based authentication allows CAS to detect suspicious and seemingly-fraudulent authentication requests based on past user behavior and collected authentication events, statistics, etc. Once and after primary authentication where the principal is identified, the authentication transaction is analyzed via a number of configurable criteria and fences to determine how risky the attempt may be. The result of the evaluation step is a cumulative risk score that is then weighed against a risk threshold set by the CAS operator. In the event that the authentication attempt is considered risky well beyond the risk threshold, CAS may be allowed to take action and mitigate that risk.

In summary, the story told is:

If an authentication request is at least [X%] risky, take action to mitigate that risk.

The functionality of this feature is ENTIRELY dependent upon collected statistics and authentication events in the past. Without data, there is nothing to analyze and no risk to detect.

Note that evaluation of attempts and mitigation of risks are all recorded in the audit log.

Adaptive Authentication

If you need to preemptively evaluate authentication attempts based on various characteristics of the request, you may be interested in this guide instead.

A few notes to remember:

You MUST allow and configure CAS to track and record authentication events.
You MUST allow and configure CAS to geolocate authentication requests.
If the selected contingency plan is to force the user into a multifactor authentication flow, you then MUST configure CAS for multifactor authentication and the relevant provider.

Configuration

Support is enabled by including the following dependency in the overlay:

<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-support-electrofence</artifactId>
    <version>${cas.version}</version>
</dependency>

implementation "org.apereo.cas:cas-server-support-electrofence:${project.'cas.version'}"

dependencyManagement {
    imports {
        mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
    }
}

dependencies {
    implementation "org.apereo.cas:cas-server-support-electrofence"
}

dependencies {
    /*
        The following platform references should be included automatically and are listed here for reference only.

        implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
        implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
        
    */
    implementation "org.apereo.cas:cas-server-support-electrofence"
}

The following settings and properties are available from the CAS configuration catalog:

_{The configuration settings listed below are tagged as Required in the CAS configuration metadata. This flag indicates that the presence of the setting may be needed to activate or affect the behavior of the CAS feature and generally should be reviewed, possibly owned and adjusted. If the setting is assigned a default value, you do not need to strictly put the setting in your copy of the configuration, but should review it nonetheless to make sure it matches your deployment expectations.}

cas.authn.adaptive.risk.core.threshold=0.6

The risk threshold factor beyond which the authentication event may be considered risky.

org.apereo.cas.configuration.model.core.authentication.risk.RiskBasedAuthenticationCoreProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value. The only possible exception to this rule is when naming actuator endpoints; The name of the actuator endpoints (i.e. ssoSessions) MUST remain in camelCase mode.

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.authn.adaptive.risk.core.threshold=0.6

This is the most common form of property configuration that is recognized by CAS, regardless of the actual property source, which might in fact be managed separately outside the CAS environment, by another system or cloud framework.

CAS properties can be specified using the YAML syntax:

cas: 
  authn: 
    adaptive: 
      risk: 
        core: 
          threshold: "0.6"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.authn.adaptive.risk.core.threshold="0.6" -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory. Note the placement of the system property which must be specified before the CAS web application is launched.

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_AUTHN_ADAPTIVE_RISK_CORE_THRESHOLD="0.6"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.authn.adaptive.risk.core.threshold="0.6"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

_{The configuration settings listed below are tagged as Optional in the CAS configuration metadata. This
flag indicates that the presence of the setting
is not immediately necessary in the end-user CAS configuration, because a default value is assigned or
the activation of the feature is not conditionally controlled by the setting value. In other words, you should only include this field in your
configuration if you need to modify the default value or if you need to turn on the feature controlled by the setting.}

cas.authn.adaptive.risk.core.days-in-recent-history=30

Indicates how far back the search in authentication history must go in order to locate authentication events.

org.apereo.cas.configuration.model.core.authentication.risk.RiskBasedAuthenticationCoreProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.authn.adaptive.risk.core.days-in-recent-history=30

CAS properties can be specified using the YAML syntax:

cas: 
  authn: 
    adaptive: 
      risk: 
        core: 
          days-in-recent-history: "30"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.authn.adaptive.risk.core.days-in-recent-history="30" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_AUTHN_ADAPTIVE_RISK_CORE_DAYS_IN_RECENT_HISTORY="30"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.authn.adaptive.risk.core.days-in-recent-history="30"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

Configuration Metadata

The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.

Be Selective

This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.

YAGNI

Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.

Naming Convention

Property names can be specified in very relaxed terms. For instance cas.someProperty, cas.some-property, cas.some_property are all valid names. While all forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those that might be presented to the system via an external library or framework such as Spring Boot, etc.

Note

Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas. All other settings are controlled and provided to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the way you intend.

Validation

Configuration properties are automatically validated on CAS startup to report issues with configuration binding, specially if defined CAS settings cannot be recognized or validated by the configuration schema. Additional validation processes are also handled via Configuration Metadata and property migrations applied automatically on startup by Spring Boot and family.

Indexed Settings

CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value. The index [0] is meant to be incremented by the adopter to allow for distinct multiple configuration blocks.

Risk Calculation

You need to configure CAS to allow it to detect suspicious and seemingly-fraudulent authentication requests based on past user behavior and collected authentication events, statistics, etc.

See this guide for more info.

Risk Mitigation

Once an authentication attempt is deemed risky, you need to configure CAS to decide how to handle and respond to the authentication attempt.

See this guide for more info.