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.

Risk Calculation

One or more risk calculators may be enabled to allow an analysis of authentication requests.

A high-level explanation of the risk calculation strategy follows:

If there is no recorded event at all present for the principal, consider the request suspicious.
If the number of recorded events for the principal based on the active criteria matches the total number of events, consider the request safe.

IP Address

This calculator looks into past authentication events that match the client ip address. It is applicable if you wish to consider authentication requests from unknown ip addresses suspicious for the user. The story here is:

Find all past authentication events that match the current client ip address and calculate an averaged score.

Browser User Agent

This calculator looks into past authentication events that match the client’s user-agent string. It is applicable if you wish to consider authentication requests from unknown browsers suspicious for the user. The story here is:

Find all past authentication events that match the current client browser and calculate an averaged score.

Geolocation

This calculator looks into past authentication events that contain geolocation data, and compares those with the current geolocation. If current geolocation data is unavailable, it will attempt to geocode the location based on the current client ip address. This feature mostly depends on whether or not geodata is made available to CAS via the client browser and requires geotracking of authentication requests.

The story here is:

Find all past authentication events that match the current client location and calculate an average score.

Date/Time

This calculator looks into past authentication events that fit within the defined time-window. It is applicable if you wish to consider authentication requests outside that window suspicious for the user. The story here is:

Find all past authentication events that are established X hours before/after now and calculate an averaged score.

Risk Mitigation

Once an authentication attempt is deemed risky, a contingency plan may be enabled to mitigate risk. If configured and allowed, CAS may notify both the principal and deployer via both email and sms.

Block Authentication

Prevent the authentication flow to proceed and disallow the establishment of the SSO session.

Multifactor Authentication

Force the authentication event into a multifactor flow of choice, identified by the provider id.

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"
}

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.}

_{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. You should only include this field in your
configuration if you need to modify the default value.}

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.

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.

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. The validation process is on by default and can be skipped on startup using a special system property SKIP_CONFIG_VALIDATION that should be set to true. 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.

Messaging & Notifications