Zot Bug: FIPS Mode Incompatible Password Hashing

Introduction

This article addresses a critical bug in the Project Zot, specifically related to its operation in FIPS (Federal Information Processing Standards) mode. The core issue revolves around the use of bcrypt for password hashing, which is not an approved cipher for FIPS compliance. This poses a significant security concern for environments requiring adherence to FIPS standards. We will delve into the technical details of the bug, its implications, and potential solutions to ensure Zot aligns with stringent security requirements. The resolution of this issue is paramount for maintaining the integrity and security of systems that rely on Zot for container image management, especially within government and regulated industries.

Understanding the FIPS Compliance Issue

When operating in FIPS mode, systems must adhere to a strict set of cryptographic standards to ensure data security. The bug in question highlights a violation of these standards within Project Zot. While a previous fix addressed the use of SHA1, the current implementation utilizes bcrypt for htpasswd hashing. Bcrypt, while a robust hashing algorithm, is not FIPS-approved, creating a compliance conflict. This means that any system running Zot in FIPS mode is technically non-compliant, potentially exposing it to security vulnerabilities and regulatory penalties. The core of the problem lies in the selection of hashing algorithms. FIPS mode mandates the use of specific approved algorithms, such as SHA256 or SHA512, for cryptographic operations, including password hashing. Therefore, the continued use of bcrypt represents a critical oversight that needs immediate attention to bring Zot into full compliance.

Technical Deep Dive: The Problem with Bcrypt in FIPS Mode

To fully grasp the issue, let's examine the technical aspects. The problematic code snippet resides in pkg/api/htpasswd.go, where bcrypt is employed for hashing passwords. While bcrypt is widely recognized for its strength and resistance to brute-force attacks, it is not among the approved cryptographic algorithms for FIPS compliance. This discrepancy creates a direct conflict when Zot operates in FIPS mode. The FIPS standard dictates that only approved algorithms can be used for cryptographic functions. This is to ensure that the algorithms have been thoroughly vetted and are considered secure against known attacks. Bcrypt, while secure in many contexts, does not meet this stringent requirement for FIPS compliance. Therefore, the use of bcrypt in htpasswd hashing renders Zot non-compliant in FIPS mode. To rectify this, the hashing mechanism must be replaced with a FIPS-approved alternative, such as SHA256 or SHA512.

Proposed Solutions: SHA256/SHA512 and Yescrypt

Addressing the FIPS compliance issue requires replacing bcrypt with an approved hashing algorithm. Two primary solutions present themselves: SHA256/SHA512 and Yescrypt. SHA256 and SHA512 are FIPS-approved hashing algorithms that provide a secure and compliant alternative to bcrypt. Implementing either of these algorithms would immediately resolve the compliance issue. However, SHA256 and SHA512 are designed for speed, which can make them vulnerable to brute-force attacks if not properly salted and iterated. This is where Yescrypt comes into play. Yescrypt is a cost-based hashing algorithm that leverages SHA256 under the hood. It is based on scrypt, another well-regarded hashing algorithm, and is considered compliant with FIPS standards. Yescrypt's design incorporates features that make it resistant to brute-force attacks, such as adaptive iteration counts and salt values. Furthermore, many Linux distributions have adopted Yescrypt as the default hashing algorithm due to its security and compliance benefits. Therefore, implementing Yescrypt would not only resolve the FIPS compliance issue but also enhance the overall security of password hashing within Zot. The choice between SHA256/SHA512 and Yescrypt depends on the specific security requirements and performance considerations of the system. However, both options provide viable paths to achieving FIPS compliance.

Reproducing the Bug

To reproduce this bug, follow these steps:

1. Configuration: Configure your system to operate in FIPS mode. This typically involves setting specific kernel parameters and configuring cryptographic libraries to use only FIPS-approved algorithms.
2. Client Tool: Utilize any client tool that interacts with Zot's authentication mechanism, such as a command-line interface or a web browser.
3. Observed Error: Attempt to authenticate using a password. The system will use bcrypt for hashing, which will violate FIPS compliance and may trigger errors or warnings in the system logs. These errors may not be immediately apparent, but they indicate a non-compliant state that could lead to security vulnerabilities.

By following these steps, you can verify that the use of bcrypt in htpasswd hashing creates a FIPS compliance issue within Zot.

Expected Behavior

The expected behavior in FIPS mode is that all cryptographic operations, including password hashing, must use FIPS-approved algorithms. Therefore, the correct behavior would be for Zot to utilize SHA256, SHA512, or Yescrypt for hashing passwords instead of bcrypt. This would ensure that the system operates in full compliance with FIPS standards and maintains a secure cryptographic posture. The absence of this behavior constitutes the bug described in this article.

Implications and Risks

The implications of this bug are significant, particularly for organizations that require FIPS compliance. Failure to adhere to FIPS standards can result in:

• Security vulnerabilities: Non-compliant cryptographic operations can introduce weaknesses that attackers can exploit.
• Regulatory penalties: Organizations operating in regulated industries may face fines or sanctions for non-compliance.
• Reputational damage: A security breach resulting from non-compliance can damage an organization's reputation and erode trust with customers.

Therefore, addressing this bug is crucial for mitigating these risks and ensuring the security and compliance of systems that rely on Zot.

Steps to Resolve the Issue

To resolve the FIPS compliance issue, the following steps should be taken:

1. Identify the problematic code: Locate the code in pkg/api/htpasswd.go where bcrypt is used for password hashing.
2. Replace bcrypt with a FIPS-approved algorithm: Implement either SHA256, SHA512, or Yescrypt as the hashing mechanism.
3. Test the solution: Thoroughly test the new hashing mechanism to ensure it functions correctly and complies with FIPS standards.
4. Deploy the fix: Deploy the updated code to production environments.
5. Monitor the system: Continuously monitor the system to ensure ongoing FIPS compliance.

By following these steps, you can effectively resolve the FIPS compliance issue and maintain a secure and compliant system.

Conclusion

The bug in Project Zot, where bcrypt is used for password hashing in FIPS mode, represents a significant security and compliance risk. By understanding the technical details of the bug, its implications, and the proposed solutions, organizations can take the necessary steps to resolve the issue and ensure the security and compliance of their systems. Implementing SHA256, SHA512, or Yescrypt as the hashing mechanism will bring Zot into full compliance with FIPS standards and mitigate the risks associated with non-compliant cryptographic operations. Addressing this bug is crucial for maintaining the integrity and security of systems that rely on Zot for container image management, especially within government and regulated industries.

For more information on FIPS compliance, visit the NIST (National Institute of Standards and Technology) website: NIST