Description

Detects the use of weak RSA padding (PKCS#1 v1.5) in C# cryptographic operations through RSA.CreateKeyExchange and RSA.DecryptKeyExchange methods. This padding scheme is vulnerable to padding oracle attacks which could lead to decryption of encrypted messages.

Detection Strategy

• Identifies calls to RSA.CreateKeyExchange or RSA.DecryptKeyExchange methods

• Verifies if the RSA operation uses the legacy PKCS#1 v1.5 padding scheme by checking the class context

• Reports a vulnerability when these cryptographic operations are found with the insecure padding configuration

Vulnerable code example

using System.Security.Cryptography;

public class VulnerableRSA 
{
    public static void EncryptUnsafe() 
    {
        RSA key = RSA.Create();
        byte[] data = new byte[16];...

✅ Secure code example

using System.Security.Cryptography;

public class SecureRSA 
{
    public static void EncryptSafe() 
    {
        RSA key = RSA.Create();
        byte[] data = new byte[16];...