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Buildkit credentials inlined to Git URLs could end up in provenance attestation

Moderate severity GitHub Reviewed Published Mar 6, 2023 in moby/buildkit • Updated Sep 20, 2023

Package

gomod github.com/moby/buildkit (Go)

Affected versions

>= 0.10.0, < 0.11.4

Patched versions

0.11.4

Description

When the user sends a build request that contains a Git URL that contains credentials and the build creates a provenance attestation describing that build, these credentials could be visible from the provenance attestation.

Git URL can be passed in two ways:

  1. Invoking build directly from a URL with credentials.
buildctl build --frontend dockerfile.v0 --context https://<credentials>@url/repo.git

Equivalent in docker buildx would be

docker buildx build https://<credentials>@url/repo.git
  1. If the client sends additional VCS info hint parameters on builds from a local source. Usually, that would mean reading the origin URL from .git/config file.

Thanks to Oscar Alberto Tovar for discovering the issue.

Impact

When a build is performed under specific conditions where credentials were passed to BuildKit they may be visible to everyone who has access to provenance attestation.

Provenance attestations and VCS info hints were added in version v0.11.0. Previous versions are not vulnerable.

In v0.10, when building directly from Git URL, the same URL could be visible in BuildInfo structure that is a predecessor of Provenance attestations. Previous versions are not vulnerable.

Note: Docker Build-push Github action builds from Git URLs by default but is not affected by this issue even when working with private repositories because the credentials are passed with build secrets and not with URLs.

Patches

Bug is fixed in v0.11.4 .

Workarounds

It is recommended to pass credentials with build secrets when building directly from Git URL as a more secure alternative than modifying the URL.

In Docker Buildx, VCS info hint can be disabled by setting BUILDX_GIT_INFO=0. buildctl does not set VCS hints based on .git directory, and values would need to be passed manually with --opt.

References

References

@tonistiigi tonistiigi published to moby/buildkit Mar 6, 2023
Published by the National Vulnerability Database Mar 6, 2023
Published to the GitHub Advisory Database Mar 7, 2023
Reviewed Mar 7, 2023
Last updated Sep 20, 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
None
User interaction
Required
Scope
Unchanged
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:N/UI:R/S:U/C:H/I:N/A:N

EPSS score

0.187%
(57th percentile)

Weaknesses

CVE ID

CVE-2023-26054

GHSA ID

GHSA-gc89-7gcr-jxqc

Source code

Credits

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