CAS Vulnerability Disclosure


Overview

This is the public version of an Apereo CAS project vulnerability disclosure, describing an issue in CAS where an adversary may be able to bypass the second factor (token) although MFA is requested during the login process.

This issue applies to all MFA providers except the Duo provider (which is therefore NOT vulnerable).

Affected Deployments

The attack vector applies to all deployments of the CAS server for the versions:

  • 5.3.0, 5.3.1 and 5.3.2
  • lower or equal to 5.2.6.

If you have deployed the version 5.3.0, 5.3.1 or 5.3.2, you MUST upgrade to the version 5.3.3.

If you have deployed a version lower or equal to version 5.2.6, you MUST upgrade to the version 5.2.7.

Severity

This is a serious issue where successfully exercising this vulnerability allows the adversary to bypass the second factor (token) required by the MFA policy. This makes any MFA configuration to re-inforce security completely useless.

Patching

Patch releases are available to address CAS vulnerable deployments. Upgrades to the next patch version for each release should be a drop-in replacement. The patch simply ensures that the MFA factor (token) is effectively required when MFA is requested.

Timeline

The issue was originally reported to the CAS application security team on August, 2018 and upon confirmation, CAS was patched.

Procedure

Modify your CAS overlay to point to the version 5.2.7 or 5.3.3. A snippet of a pom.xml for a CAS overlay follows:

<dependencies>
    <dependency>
        <groupId>org.apereo.cas</groupId>
        <artifactId>cas-server-webapp</artifactId>
        <version>${cas.version}</version>
        <type>war</type>
        <scope>runtime</scope>
    </dependency>
</dependencies>

<properties>
    <cas.version>5.3.3</cas.version>
</properties>

Support

If you have questions on the details of this vulnerability and how it might be reproduced, please contact security@apereo.org or cas-appsec-public@apereo.org.

Resources

Jérôme LELEU

Related Posts

Apereo CAS is now on Develocity

An overview of how Apereo CAS is using Gradle and Develocity to improve its build and test execution cycle.

CAS OAuth/OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the Apereo CAS software acting as an OAuth/OpenID Connect provider.

CAS Groovy Vulnerability Disclosure

Disclosure of a security issue with the Apereo CAS software when using Groovy.

CAS OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the Apereo CAS software acting as an OpenID Connect Provider.

CAS X.509 Vulnerability Disclosure

Disclosure of a security issue with the CAS software and its X.509 features.

CAS OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the CAS software acting as an OpenID Connect Provider.

CAS OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the CAS software acting as an OpenID Connect Provider.

CAS OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the CAS software acting as an OpenID Connect Provider.

CAS Spring Framework RCE Vulnerability Disclosure

Disclosure of the Spring framework RCE security issue with the Apereo CAS software.

CAS OpenID Connect Vulnerability Disclosure

Disclosure of a security issue with the CAS software acting as an OpenID Connect Provider.