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Insecure authentication method - LDAP

Need​

Secure and robust authentication method for the system

Context​

  • Usage of Scala for building scalable and functional applications
  • Usage of play.api for building web applications in Scala
  • Usage of javax.naming for accessing and manipulating naming and directory services in Java
  • Usage of javax.naming.directory for accessing and manipulating directory services in Java

Description​

Non compliant code​

import play.api._
import play.api.mvc._
import javax.naming._
import javax.naming.directory._

class Application extends Controller {
  def authenticate = Action { request =>
    val username = request.body.asFormUrlEncoded.get("username")(0)
    val password = request.body.asFormUrlEncoded.get("password")(0)

    val env = new java.util.Hashtable[String, String]
    env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory")
    env.put(Context.PROVIDER_URL, "ldap://localhost:389")
    env.put(Context.SECURITY_AUTHENTICATION, "simple")
    env.put(Context.SECURITY_PRINCIPAL, s"cn=$username,dc=example,dc=com")
    env.put(Context.SECURITY_CREDENTIALS, password)

    try {
      val ctx = new InitialDirContext(env)
      Ok("Authenticated")
    } catch {
      case e: AuthenticationException => Unauthorized("Authentication failed")
    }
  }
}

This Scala code uses the Play framework to create an HTTP endpoint that authenticates users against an LDAP server. The authenticate method retrieves the username and password from the request body and uses them to create an InitialDirContext object, which represents an LDAP context for the given credentials.

The InitialDirContext constructor will attempt to connect to the LDAP server and authenticate the user. If the authentication succeeds, it returns a 200 OK response. If the authentication fails, it throws an AuthenticationException, which is caught and results in a 401 Unauthorized response.

However, this code is vulnerable to man-in-the-middle (MITM) attacks because it uses the insecure "simple" authentication method, which sends the password in plaintext over the network. This means that an attacker who can intercept the network traffic can easily obtain the user's password.

Moreover, the code does not use any encryption for the LDAP communication, which makes it easy for an attacker to read all LDAP queries and responses, including the plaintext password.

Finally, the code does not validate the LDAP server's SSL certificate, which means that it is susceptible to SSL certificate spoofing. An attacker could set up a fake LDAP server with a forged certificate, and the code would happily send the user's credentials to this fake server.

Steps​

  • Replace the use of LDAP with a more secure authentication method, such as OAuth or JWT.
  • Avoid sending passwords over the network in plain-text. Use secure protocols like HTTPS to encrypt the communication.
  • Implement strong password hashing algorithms, such as bcrypt, to securely store and compare passwords.
  • Implement multi-factor authentication to add an extra layer of security.
  • Regularly update and patch the LDAP server software to ensure it is not vulnerable to known security issues.
  • Implement proper certificate validation to prevent SSL certificate spoofing.
  • Consider using a dedicated authentication service instead of relying on LDAP for authentication.

Compliant code​

import play.api._
import play.api.mvc._
import pdi.jwt._
import java.time.Clock
import javax.crypto.spec.SecretKeySpec
import javax.xml.bind.DatatypeConverter

class Application extends Controller {
  private val secretKey = "your-secret-key"
  private val keySpec = new SecretKeySpec(DatatypeConverter.parseBase64Binary(secretKey), "HmacSHA256")
  private val clock = Clock.systemUTC()

  def authenticate = Action { request =>
    val username = request.body.asFormUrlEncoded.get("username")(0)
    val password = request.body.asFormUrlEncoded.get("password")(0)

    // Replace this with your actual user authentication logic
    if (username == "admin" && password == "password") {
      val claim = JwtClaim()
        .issuedNow(clock)
        .expiresIn(60 * 60, clock) // 1 hour
        .startsNow(clock)
        .+("user", username)

      val token = JwtJson.encode(claim, keySpec, JwtAlgorithm.HS256)
      Ok("Authenticated").withCookies(Cookie("access_token", token))
    } else {
      Unauthorized("Authentication failed")
    }
  }
}

The above code replaces the insecure LDAP authentication with JWT (JSON Web Token) authentication, which is a more secure method.

The secretKey is used to sign the JWT. This should be a strong key that is kept secret. The keySpec is a SecretKeySpec that is used to sign the JWT with the HMAC SHA256 algorithm.

The authenticate method now checks the username and password against a hardcoded "admin" and "password". This is just for demonstration purposes and should be replaced with your actual user authentication logic.

If the username and password are correct, a JWT is created with the JwtClaim method. The JWT is issued now, expires in 1 hour, and starts now. The username is added to the JWT as a claim.

The JWT is then encoded with the JwtJson.encode method, using the keySpec and the HMAC SHA256 algorithm. The resulting JWT is sent back to the client in a cookie.

If the username and password are incorrect, an "Authentication failed" message is returned.

This code is more secure than the original code because it does not use the insecure LDAP authentication method, does not send passwords over the network in plain-text, and uses a secure JWT for authentication.

References​

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