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March 13, 2025
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How to Fix CVE-2025-27403: Azure Container Registry Authentication Vulnerability?
Ratify, a Kubernetes verification engine, has a vulnerability that could allow attackers to potentially extract and abuse Entra ID (EID) tokens with Azure Container Registry (ACR) access. This flaw, tracked as CVE-2025-27403, arises from improper validation during token exchange with private ACRs. Specifically, prior to versions 1.2.3 and 1.3.2, Ratify didn't properly verify the target registry, potentially leading to token misuse if a workload contained a malicious registry reference. This article provides security professionals with the necessary information to understand, detect, and remediate this vulnerability, ensuring the security of their Kubernetes environments.
A Short Introduction to Ratify
Ratify is a verification engine for Kubernetes, designed to ensure that only compliant artifacts are deployed. It acts as an admission controller, inspecting container images and other deployable artifacts against defined policies before allowing them to run in the cluster. Ratify can verify various types of security metadata, such as signatures, attestations, and vulnerability scan results, enabling organizations to enforce security best practices and compliance requirements within their containerized environments. By integrating with artifact registries and policy engines, Ratify provides a comprehensive solution for securing the software supply chain in Kubernetes.
Summary of CVE-2025-27403
CVE ID: CVE-2025-27403
Description: Improper Authentication vulnerability in Ratify leading to potential misuse of Entra ID tokens with ACR access.
CVSS Score: 7.2 (HIGH)
CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:H/SI:H/SA:L
This vulnerability stems from a lack of proper validation in Ratify's Azure authentication providers. When configured to authenticate to a private ACR, Ratify attempts to exchange an Entra ID (EID) token for an ACR refresh token. However, versions prior to 1.2.3 and 1.3.2 failed to verify that the target registry was indeed an ACR endpoint. This could allow a malicious actor to present the EID token to a non-ACR registry during the token exchange process, potentially leading to unauthorized access and token compromise if a user workload contains an image reference to a malicious registry. The updated versions now validate against a pre-configured list of well-known ACR endpoints. One should know what is a vulnerability before diving deep into it.
Impact of CVE-2025-27403
The exploitation of CVE-2025-27403 can have significant security implications for organizations using Ratify with Azure Container Registries. The primary risk is the potential extraction and abuse of Entra ID (EID) tokens with ACR access. If an attacker can trick Ratify into presenting an EID token to a malicious registry, they could gain unauthorized access to the token.
This compromised token could then be used to perform unauthorized actions within the ACR, such as pulling or pushing images, modifying repository metadata, or even deleting entire repositories. Furthermore, if the compromised token has broader permissions within the Azure environment, the attacker could potentially escalate their privileges and gain access to other resources. The vulnerability's impact extends beyond just the container registry, potentially affecting the overall security posture of the organization's cloud infrastructure. To protect your system, you need a strong patch management strategy.
Products Affected by CVE-2025-27403
The following versions of Ratify are affected by this vulnerability:
|
Product
|
Version(s) Affected
|
Fixed Version(s)
|
|---|---|---|
|
Ratify
|
< 1.2.3
|
1.2.3
|
|
Ratify
|
< 1.3.2
|
1.3.2
|
It is important to note that only users who have configured a private ACR to be used with the Azure authentication providers are impacted by this vulnerability. Users who are not using Azure authentication providers or are using versions 1.2.3 or later are not affected. The list of impacted products are mentioned in the NVD details.
How to Check If Your Product Is Vulnerable?
To determine if your Ratify deployment is vulnerable, follow these steps:
Check the Ratify Version: Determine the version of Ratify that is currently deployed in your Kubernetes cluster. You can typically find this information in the Ratify deployment manifest or by querying the Ratify pod directly.
Review Azure Authentication Provider Configurations: Inspect your Ratify configuration to determine if you are using the Azure workload identity or Azure managed identity authentication providers. If you are not using these providers, your deployment is not vulnerable.
Inspect Image References: Examine your Kubernetes workloads for image references that point to potentially untrusted or unknown registries. If your workloads only reference images from trusted ACR endpoints, the risk is reduced.
Verify Registry Domain Validation (If patched): If you've applied the patch (upgraded to v1.2.3 or v1.3.2), ensure the registry domain validation is configured correctly. Check that your Ratify configuration includes a list of well-known ACR endpoints and that the registry domain of your images matches one of these endpoints. Security teams can use SOAR platforms for automation.
How to Fix the Vulnerability?
The primary remediation strategy for CVE-2025-27403 is to upgrade Ratify to a patched version. Follow these steps to mitigate the vulnerability:
Upgrade Ratify: Upgrade your Ratify deployment to version 1.2.3 or 1.3.2 or later. These versions include the necessary validation logic to prevent token exchange with non-ACR registries. Refer to the official Ratify documentation for instructions on how to upgrade your deployment.
Verify Azure Authentication Provider Configurations: After upgrading, carefully review your Azure authentication provider configurations to ensure they are correctly configured and that the necessary permissions are in place.
Implement Strict Registry Domain Validation: Configure Ratify to enforce strict registry domain validation. This involves specifying a list of well-known ACR endpoints that Ratify is authorized to exchange tokens with. Ensure that this list is comprehensive and includes all of the ACR endpoints that your workloads use.
Monitor for Unauthorized Token Exchanges: Implement monitoring and alerting to detect any unauthorized token exchanges. This could involve monitoring Ratify logs for suspicious activity or using a SIEM system to correlate events across your Kubernetes environment.
Review and Restrict Container Registry Access Permissions: As a general security best practice, review and restrict container registry access permissions to only those users and services that require it. This can help to limit the potential impact of a compromised token.
Workarounds:
While upgrading to a patched version is the recommended solution, the following workarounds can provide temporary protection:
Disable Azure Authentication Providers (If Possible): If your environment allows, consider temporarily disabling the Azure workload identity and Azure managed identity authentication providers. This will prevent Ratify from exchanging tokens with ACRs, effectively mitigating the vulnerability.
Restrict Network Access: Implement network policies to restrict Ratify's access to only trusted ACR endpoints. This can help to prevent Ratify from communicating with malicious registries. If you suspect a breach, initiating a cyber incident response plan is crucial.
It is highly recommended to upgrade to the patched versions as soon as possible to ensure the long-term security of your Ratify deployment. Monitor official Ratify channels for any additional security updates or patches related to this vulnerability.
By implementing these remediation steps, security professionals can effectively mitigate the risk posed by CVE-2025-27403 and protect their Kubernetes environments from potential attacks.
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Arun KL
Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.
