CVE-2020-5206: Authentication Bypass For Endpoints With Anonymous Access in Opencast

Impact

Using a remember-me cookie with an arbitrary username can cause Opencast to assume proper authentication for that user even if the remember-me cookie was incorrect given that the attacked endpoint also allows anonymous access.

This way, an attacker can, for example, fake a remember-me token, assume the identity of the global system administrator and request non-public content from the search service without ever providing any proper authentication.

Patches

This problem is fixed in Opencast 7.6 and Opencast 8.1

Workarounds

As a workaround for older, unpatched versions, disabling remember-me cookies in etc/security/mh_default_org.xml will mitigate the problem but will obviously also disable this feature without obvious indication. To deactivate this, remove the following line from the security configuration:

<sec:remember-me … />

References

• Remember-me cookie in the security configuration file

For more information

If you have any questions or comments about this advisory:

• Open an issue in opencast/opencast
• For security-relevant information, email us at security@opencast.org