Resolve vulnerability: Use of a Broken or Risky Cryptographic Algorithm

AI GENERATED MERGE REQUEST

The suggested code changes were generated by GitLab Duo Vulnerability resolution, an AI feature. Use this feature with caution. Before you apply the code changes, carefully review and test them, to ensure that they solve the vulnerability.

The large language model that generated the suggested code changes was provided with only the affected lines of code, and the vulnerability in that code. It is not aware of any functionality outside of this context.

Please see our documentation for more information about this feature.

Description:

Usage of a cryptographically insecure algorithm has been detected. It is recommended that alternative algorithms be used instead.

• Severity: medium
• Confidence: unknown
• Location: vulnerability/csa/csa.go:62

Analysis:

The vulnerability report indicates a "Use of a Broken or Risky Cryptographic Algorithm" issue, specifically referencing CWE-327 and Gosec Rule G401. The vulnerable code section highlights the use of the MD5 hashing algorithm.

MD5 is considered cryptographically broken and unsuitable for security-critical applications. It has known vulnerabilities, including collision resistance weaknesses, making it susceptible to various attacks.

In the context of this code, MD5 is being used to hash a one-time password (OTP) for verification purposes. This is a security-critical operation, and using a weak hashing algorithm like MD5 significantly reduces the security of the OTP verification process.

The Md5Sum function is directly implementing MD5 hashing, which is the root of the vulnerability. This function is called in the verifyHandler to compare the submitted OTP with a stored hash.

Given the security implications and the specific use case, this vulnerability is not a false positive and should be addressed.

Summary:

1. The reported vulnerability is the use of MD5, a broken cryptographic hash function, for security-critical operations (CWE-327).

2. The fix replaces the Md5Sum function with a new SecureHash function that uses SHA-256 instead of MD5. Here's a breakdown of the changes:

   import (
       "crypto/sha256"
       "encoding/hex"
   )
   
   func SecureHash(text string) string {
       hasher := sha256.New()
       hasher.Write([]byte(text))
       return hex.EncodeToString(hasher.Sum(nil))
   }

   This fix addresses the security concern by:

   • Using SHA-256, a significantly more secure hashing algorithm that is currently considered cryptographically strong.
   • Maintaining the same function signature and return type, ensuring compatibility with existing code.
   • Preserving the original functionality of creating a hash from input text.

3. To fully implement this fix, all calls to Md5Sum in the codebase should be replaced with SecureHash. Additionally, any stored hashes (like the sotp variable in verifyHandler) will need to be updated to use the new SHA-256 hashes.

This change significantly improves the security of the OTP verification process by using a cryptographically strong hashing algorithm, mitigating risks associated with hash collisions and other vulnerabilities present in MD5.

Identifiers:

• CWE-327
• A9:2017 - Using Components with Known Vulnerabilities
• gosec.G401-1
• Gosec Rule ID G401