Opencast before 7.6 and 8.1 enables a remember-me cookie based on a hash created from the username, password, and an additional system key. This means that an attacker getting access to a remember-me token for one server can get access to all servers which allow log-in using the same credentials without ever needing the credentials. This problem is fixed in Opencast 7.6 and Opencast 8.1

Affected: Maven: org.opencastproject:opencast-kernel

### Impact

The security configuration in `etc/security/mh_default_org.xml` enables a remember-me cookie based on a hash created from the [username, password, and an additional system key](https://docs.spring.io/spring-security/site/docs/3.0.x/reference/remember-me.html). Opencast has hard-coded this system key in the large XML file and never mentions to change this, basically ensuring that all systems use the same key:

```xml <sec:remember-me key="opencast" user-service-ref="userDetailsService" /> ```

This means that an attacker getting access to a remember-me token for one server can get access to all servers which allow log-in using the same credentials without ever needing the credentials. For example, a remember-me token obtained from develop.opencast.org can be used on stable.opencast.org without actually knowing the log-in credentials.

Such an attack will usually not work on different installations – assuming that safe, unique passwords are used – but it is basically guaranteed to work to get access to all machines of one cluster if a token from one machine is compromised.

### Patches

This problem is fixed in Opencast 7.6 and Opencast 8.1

### Workarounds

We strongly recommend updating to the patched version. Still, as a workaround for older versions, in `etc/security/mh_default_org.xml`, set a custom key for each server:

```xml <sec:remember-me key="CUSTOM_RANDOM_KEY" user-service-ref="userDetailsService" /> ```

### References

- [Relevant lines in the securi…