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Hard-Coded Key Used For Remember-me Token in Opencast

Moderate severity GitHub Reviewed Published Jan 29, 2020 in opencast/opencast • Updated Jan 9, 2023

Package

maven org.opencastproject:opencast-kernel (Maven)

Affected versions

< 7.6
>= 8.0, < 8.1

Patched versions

7.6
8.1

Description

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. 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:

<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:

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

References

For more information

If you have any questions or comments about this advisory:

Thanks

Thanks to @LukasKalbertodt for reporting the issue.

References

@lkiesow lkiesow published to opencast/opencast Jan 29, 2020
Reviewed Jan 30, 2020
Published to the GitHub Advisory Database Jan 30, 2020
Last updated Jan 9, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

EPSS score

0.104%
(44th percentile)

Weaknesses

CVE ID

CVE-2020-5222

GHSA ID

GHSA-mh8g-hprg-8363

Source code

No known source code

Credits

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