Description

Cosign provides container signing, verification, and storage in an OCI registry for the sigstore project. Prior to version 1.5.2, Cosign can be manipulated to claim that an entry for a signature exists in the Rekor transparency log even if it doesn't. This requires the attacker to have pull and push permissions for the signature in OCI. This can happen with both standard signing with a keypair and "keyless signing" with Fulcio. If an attacker has access to the signature in OCI, they can manipulate cosign into believing the entry was stored in Rekor even though it wasn't. The vulnerability has been patched in v1.5.2 of Cosign. The `signature` in the `signedEntryTimestamp` provided by Rekor is now compared to the `signature` that is being verified. If these don't match, then an error is returned. If a valid bundle is copied to a different signature, verification should fail. Cosign output now only informs the user that certificates were verified if a certificate was in fact verified. There is currently no known workaround.

Severity

 

CVSS Version 3.x CVSS Version 2.0

CVSS 3.x Severity and Metrics:

CNA:  GitHub, Inc.

Base Score:  3.3 LOW

Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: The NVD and the CNA have provided the same score. When this occurs only the CNA information is displayed, but the Acceptance Level icon for the CNA is given a checkmark to signify NVD concurrence.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score:  2.1 LOW

Vector:  (AV:L/AC:L/Au:N/C:N/I:P/A:N)

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://github.com/sigstore/cosign/commit/96d410a6580e4e81d24d112a0855c70ca3fb5b49	Patch  Third Party Advisory
https://github.com/sigstore/cosign/security/advisories/GHSA-ccxc-vr6p-4858	Third Party Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-295	Improper Certificate Validation	GitHub, Inc.

Known Affected Software Configurations Switch to CPE 2.2

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Change History

1 change records found show changes

Initial Analysis by NIST 3/07/2022 9:27:45 AM

Action	Type	Old Value	New Value
Added	CPE Configuration		OR *cpe:2.3:a:sigstore:cosign:*:*:*:*:*:*:*:* versions up to (excluding) 1.5.2
Added	CVSS V2		NIST (AV:L/AC:L/Au:N/C:N/I:P/A:N)
Added	CVSS V3.1		NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Changed	Reference Type	https://github.com/sigstore/cosign/commit/96d410a6580e4e81d24d112a0855c70ca3fb5b49 No Types Assigned	https://github.com/sigstore/cosign/commit/96d410a6580e4e81d24d112a0855c70ca3fb5b49 Patch, Third Party Advisory
Changed	Reference Type	https://github.com/sigstore/cosign/security/advisories/GHSA-ccxc-vr6p-4858 No Types Assigned	https://github.com/sigstore/cosign/security/advisories/GHSA-ccxc-vr6p-4858 Third Party Advisory