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Pomerium service account access token may grant unintended access to databroker API

High severity GitHub Reviewed Published Oct 2, 2024 in pomerium/pomerium • Updated Oct 9, 2024

Package

gomod github.com/pomerium/pomerium (Go)

Affected versions

< 0.27.1

Patched versions

0.27.1

Description

Impact

We've identified a vulnerability in the Pomerium databroker service API that may grant unintended access under specific conditions. This affects only certain Pomerium Zero and Pomerium Enterprise deployments.

Who is affected?

A Pomerium deployment is susceptible to this issue if all of the following conditions are met:

  • You have issued a service account access token using Pomerium Zero or Pomerium Enterprise.
  • The access token has an explicit expiration date in the future.
  • The core Pomerium databroker gRPC API is not otherwise secured by network access controls.

If your deployment does not meet all of these conditions, you are not affected by this vulnerability.

Details

The Pomerium databroker service is responsible for managing all persistent Pomerium application state. Requests to the databroker service API are authorized by the presence of a JSON Web Token (JWT) signed by a key known by all Pomerium services in the same deployment. However, incomplete validation of this JWT meant that some service account access tokens would incorrectly be treated as valid for the purpose of databroker API authorization.

Improper access to the databroker API could allow exfiltration of user info, spoofing of user sessions, or tampering with Pomerium routes, policies, and other settings.

Discovery

This issue was discovered during internal review. At this time we have no evidence to suggest that this vulnerability has been exploited in the wild.

Patches

We have released Pomerium v0.27.1 which includes a fix for the JWT validation logic. All affected users are strongly encouraged to upgrade to this version.

Workarounds

If you cannot upgrade immediately, consider the following mitigations:

  • Network access controls: Restrict access to the Pomerium internal gRPC API by configuring your network firewall or security groups to limit access to trusted sources only. Ensure that the port specified in the grpc_address setting is not exposed to unauthorized networks.

  • For Pomerium Zero deployments only: As of Pomerium v0.26.0, you can disable the gRPC API listener by setting grpc_address: "" in your YAML configuration file. In all-in-one mode, Pomerium does not require the internal gRPC API to be exposed beyond localhost.

For more information

If you have questions or need further assistance:

References

@kenjenkins kenjenkins published to pomerium/pomerium Oct 2, 2024
Published to the GitHub Advisory Database Oct 2, 2024
Reviewed Oct 2, 2024
Published by the National Vulnerability Database Oct 2, 2024
Last updated Oct 9, 2024

Severity

High

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 v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

0.045%
(17th percentile)

Weaknesses

CVE ID

CVE-2024-47616

GHSA ID

GHSA-r7rh-jww5-5fjr

Source code

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