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CometBFT Vote Extensions: Panic when receiving a Pre-commit with an invalid data

High severity GitHub Reviewed Published Nov 6, 2024 in cometbft/cometbft • Updated Nov 20, 2024

Package

gomod github.com/cometbft/cometbft (Go)

Affected versions

>= 0.38.0, < 0.38.15

Patched versions

0.38.15

Description

Name: ASA-2024-011: Vote Extensions: Panic when receiving a Pre-commit with an invalid data
Component: CometBFT
Criticality: High (Considerable Impact, and Possible Likelihood per ACMv1.2)
Affected versions: >= 0.38.x, unreleased v1.x and main development branches
Affected users: Chain Builders + Maintainers, Validators

Impact

A CometBFT node running in a network with vote extensions enabled could produce an invalid Vote message and send it to its peers. The invalid field of the Vote message is the ValidatorIndex, which identifies the sender in the ValidatorSet running that height of consensus. This field is ordinarily verified in the processing of Vote messages, but it turns out that in the case of a Vote message of type Precommit and for a non-nil BlockID, a logic was introduced before this ordinary verification to handle the attached vote extension. This introduced logic (not present in releases prior to 0.38.x) does not double-check the validity of the ValidatorIndex field. The result is a panic in the execution of the node receiving and processing such message.

Impact Qualification

This condition requires the introduction of malicious code in the full node sending this Vote message to its peers. Namely, nodes running upstream code cannot produce invalid Vote messages, with non-existing ValidatorIndex. Moreover, networks utilizing default behavior, where vote extensions are not enabled, are not affected by this issue.

Patches

The new CometBFT release v0.38.15 fixes this issue.

Unreleased code in the main and v1.x branches, and experimental code in the v0.38-experimental and v1.x-experimental branches are patched as well.

Workarounds

When the consensus code panics after receiving an invalid Vote message, the operator can identify the peer from which that message was received. This may require increasing the logging level of the consensus module. This peer can then be subsequently banned at the p2p layer as a temporary mitigation.

References

Timeline

  • October 21, 2024, 3:26pm PST: Issue reported to the Cosmos Bug Bounty program
  • October 21, 2024, 3:41pm PST: Issue triaged by Amulet on-call, and distributed to Core team
  • October 29, 2024, 11:35pm PST: Core team completes validation of issue
  • October 30, 2024, 3:33am PST: Core team completes patch for issue
  • October 30, 2024, 5:09am PST: Amulet creates coordination plan; schedule for distribution
  • November 4, 2024, 8:00pm GMT: Pre-notification delivered
  • November 6, 2024, 8:00am GMT: Patch made available

This issue was reported by corverroos to the Cosmos Bug Bounty Program on HackerOne on October 21, 2024. If you believe you have found a bug in the Interchain Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos.

If you have questions about Interchain security efforts, please reach out to our official communication channel at [email protected]. For more information about the Interchain Foundation’s engagement with Amulet, and to sign up for security notification emails, please see https://github.com/interchainio/security.

A Github Security Advisory for this issue is available in the CometBFT repository. For more information about CometBFT, see https://docs.cometbft.com/.

References

@cason cason published to cometbft/cometbft Nov 6, 2024
Published to the GitHub Advisory Database Nov 6, 2024
Reviewed Nov 6, 2024
Last updated Nov 20, 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 High
Attack Requirements Present
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity High
Availability High
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:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

Weaknesses

CVE ID

No known CVE

GHSA ID

GHSA-p7mv-53f2-4cwj

Source code

Credits

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