CVE-2017-12974: Improper Verification of Cryptographic Signature in Nimbus JOSE+JWT

Background

Nimbus JOSE+JWT is a Java library that provides support for JSON Web Tokens (JWT) and JSON Object Signing and Encryption (JOSE). It is commonly used for implementing secure authentication and authorization mechanisms in Java applications. However, a vulnerability has been identified in versions prior to 4.36 of the library.

Vulnerability Detail

The vulnerability in Nimbus JOSE+JWT before version 4.36 arises from the improper verification of cryptographic signatures. Specifically, the library constructs ECKey objects without ensuring that the public x and y coordinates are on the specified curve. This oversight allows attackers to exploit an Invalid Curve Attack in environments where the JCE provider lacks the applicable curve validation. The impact of this vulnerability can be significant, potentially leading to unauthorized access, data tampering, or other security breaches.

Workaround

If upgrading to the latest version is not immediately feasible, a possible workaround is to manually validate the public key coordinates against the specified curve before constructing the ECKey object. Here is an example of how this can be done using the Bouncy Castle library:

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.spec.ECParameterSpec;

// Retrieve the ECParameterSpec for the specified curve
ECParameterSpec curveParams = ECNamedCurveTable.getParameterSpec("secp256r1");

// Validate the public key coordinates against the curve
if (!curveParams.getCurve().isValidPoint(publicKey.getX(), publicKey.getY())) {
    throw new InvalidKeyException("Invalid public key coordinates");
}

// Construct the ECKey object
ECKey ecKey = new ECKey.Builder(curveParams, publicKey).build();

Note that this workaround requires the Bouncy Castle library as a dependency.

Conclusion

In conclusion, the vulnerability in Nimbus JOSE+JWT before version 4.36 allows for an Invalid Curve Attack due to improper verification of cryptographic signatures. It is crucial to upgrade to the latest version or apply the provided workaround to mitigate the risk of unauthorized access or data tampering. For further assistance or support in addressing this vulnerability, please contact DevNack.com.

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