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Ratpack's default client side session signing key is highly predictable

Moderate severity GitHub Reviewed Published Jun 29, 2021 in ratpack/ratpack • Updated Jan 29, 2023

Package

maven io.ratpack:ratpack-session (Maven)

Affected versions

< 1.9.0

Patched versions

1.9.0

Description

Impact

The client side session module uses the application startup time as the signing key by default. This means that if an attacker can determine this time, and if encryption is not also used (which is recommended, but is not on by default), the session data could be tampered with by someone with the ability to write cookies.

The default configuration is unsuitable for production use as an application restart renders all sessions invalid and is not multi-host compatible, but its use is not actively prevented.

Vulnerability Location

https://github.com/ratpack/ratpack/blob/29434f7ac6fd4b36a4495429b70f4c8163100332/ratpack-session/src/main/java/ratpack/session/clientside/ClientSideSessionConfig.java#L29

Patches

As of Ratpack 1.9.0 the default value is a securely randomly generated value, generated at application startup time.

Workarounds

Supply an alternative signing key, as per the documentation's recommendation.

References

@ldaley ldaley published to ratpack/ratpack Jun 29, 2021
Published by the National Vulnerability Database Jun 29, 2021
Reviewed Jun 30, 2021
Published to the GitHub Advisory Database Jul 1, 2021
Last updated Jan 29, 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
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
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:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS score

0.050%
(21st percentile)

CVE ID

CVE-2021-29480

GHSA ID

GHSA-2cc5-23r7-vc4v

Source code

Credits

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