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Insecure encryption algorithm - SSL/TLS

Need​

Implementation of secure encryption algorithms and disabling insecure TLS protocol versions

Context​

  • Usage of Go 1.16 for developing high-performance and efficient applications
  • Usage of crypto/tls for secure communication over TLS/SSL protocols
  • Usage of gin-gonic/gin for building web applications in Go
  • Usage of net/http for creating HTTP servers in a Node.js application

Description​

Non compliant code​

package main

import (
	"crypto/tls"
	"github.com/gin-gonic/gin"
	"net/http"
)

func main() {
	router := gin.Default()

	server := &http.Server{
		Addr:    ":8080",
		Handler: router,
		TLSConfig: &tls.Config{
			MinVersion:               tls.VersionSSL30,
			PreferServerCipherSuites: true,
		},
	}

	_ = server.ListenAndServeTLS("server.pem", "server.key")
}

The vulnerable code above is a simple Go application using the Gin framework that sets up a TLS server with a minimum version of SSL 3.0.

The vulnerability lies in the MinVersion field of the tls.Config struct. It is set to tls.VersionSSL30, which refers to SSL 3.0. SSL 3.0 is considered insecure due to numerous vulnerabilities, such as the POODLE (Padding Oracle On Downgraded Legacy Encryption) vulnerability.

The PreferServerCipherSuites field is set to true, which means that the server will choose the cipher suite from the client's list of supported cipher suites. This could lead to the selection of a weak cipher if the client supports one.

The server listens and serves on port 8080 and uses the server.pem and server.key files for the TLS configuration. The ListenAndServeTLS function starts the server with the specified certificate and key files.

To fix this vulnerability, we need to update the MinVersion field to at least tls.VersionTLS12 (TLS 1.2) or tls.VersionTLS13 (TLS 1.3), which are currently considered secure. Additionally, we should specify a list of secure cipher suites to use.

Steps​

  • Update the TLS configuration to use secure protocol versions (TLS 1.2 or higher)
  • Remove the usage of insecure TLS protocol versions (such as SSL 3.0)
  • Ensure that the server is configured to use strong cipher suites
  • Generate and use a valid SSL/TLS certificate signed by a trusted certificate authority
  • Regularly update the SSL/TLS libraries and dependencies to the latest versions

Compliant code​

package main

import (
	"crypto/tls"
	"github.com/gin-gonic/gin"
	"net/http"
)

func main() {
	router := gin.Default()

	server := &http.Server{
		Addr:    ":8080",
		Handler: router,
		TLSConfig: &tls.Config{
			MinVersion:               tls.VersionTLS12,
			PreferServerCipherSuites: true,
			CipherSuites: []uint16{
				tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
				tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
				tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
				tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			},
		},
	}

	_ = server.ListenAndServeTLS("server.pem", "server.key")
}

The original code was using an insecure TLS protocol version (SSL 3.0). This version is known to have several vulnerabilities and is not recommended for use.

The updated code now uses a secure TLS protocol version (TLS 1.2). This version is currently recommended for most applications as it provides strong security and is widely supported.

In addition, the server is now configured to use strong cipher suites. These cipher suites provide strong encryption and are recommended for most applications.

The server is also configured to prefer server cipher suites. This means that the server will choose the cipher suite to use, rather than the client. This can help to ensure that the strongest possible cipher suite is used.

Finally, the server is still configured to use an SSL/TLS certificate. This certificate should be signed by a trusted certificate authority to ensure that it is valid and trusted by clients. The certificate files ("server.pem" and "server.key") should be kept secure and should be regularly updated to ensure their security.

Regularly updating the SSL/TLS libraries and dependencies to the latest versions can also help to ensure the security of the server.

References​

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