Root escalation via symlink exchange race
Published Dec 22, 2023 · Updated Aug 27, 2024
Local privilege escalation in Buildkite Elastic CI Stack for AWS 6.7.0 and 5.22.4 allows local users to execute commands as root. The privileged fix-buildkite-agent-builds-permissions script validates PIPELINE_PATH with realpath, then recursively changes ownership by path, allowing renameat2 to replace the checked directory with a symlink before chown. A user able to run build commands as buildkite-agent can take ownership of the script, modify it, and execute it through passwordless sudo on a subsequent build.
Summary
What happened
Local privilege escalation in Buildkite Elastic CI Stack for AWS 6.7.0 and 5.22.4 allows local users to execute commands as root. The privileged fix-buildkite-agent-builds-permissions script validates PIPELINE_PATH with realpath, then recursively changes ownership by path, allowing renameat2 to replace the checked directory with a symlink before chown. A user able to run build commands as buildkite-agent can take ownership of the script, modify it, and execute it through passwordless sudo on a subsequent build.
The record
- CVE
- CVE-2023-43741
- Published
- Dec 22, 2023
- Updated
- Aug 27, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-367, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 22, 2023CVE publishedPublication date reported by the CVE source.
- Aug 27, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Buildkite symlink-exchange proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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