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Security controls bypass or absence - Tampering Protection

Need​

Implementation of tampering protection mechanisms

Context​

  • Usage of Scala for building scalable and functional applications
  • Usage of play.api.mvc for handling HTTP requests and responses in Play Framework

Description​

Non compliant code​

package controllers

import play.api.mvc._

class ApplicationController extends Controller {
  def checkRootUser = Action { implicit request =>
    val isRoot = request.headers.get("isRoot").getOrElse("false").toBoolean
    if (isRoot) {
      Ok("Root user detected")
    } else {
      Ok("Regular user")
    }
  }
}

The above code is a simple Play Framework controller written in Scala. The checkRootUser action checks if the incoming request has a header named isRoot. If the header is present and its value is true, it responds with a message indicating that a root user is detected. Otherwise, it responds with a message indicating that a regular user is detected.

The vulnerability here is that there are no security controls in place to prevent a third party from modifying and recompiling the application. This means that an attacker could potentially modify this code to always return false for the isRoot check, thereby bypassing any root user detection and gaining unauthorized access to the application.

Furthermore, there are no checks to ensure the integrity of the application code, which means that an attacker could modify the code, recompile the application, and then distribute this tampered version to users. This could lead to a wide range of security issues, including unauthorized access, data theft, and more.

To fix this vulnerability, it's necessary to implement security controls that prevent code tampering, such as code signing or checksum validation. Additionally, the application should implement proper access controls that prevent unauthorized users from gaining root access.

Steps​

  • Implement code integrity checks to ensure that the application has not been modified or tampered with.
  • Use secure coding practices to prevent unauthorized modifications to the application code.
  • Implement strong authentication and authorization mechanisms to prevent unauthorized access to sensitive functionality.
  • Regularly update and patch the application and its dependencies to address any known vulnerabilities.
  • Implement secure communication protocols, such as HTTPS, to protect data transmission between the application and clients.
  • Implement input validation and sanitization to prevent injection attacks and ensure data integrity.
  • Implement logging and monitoring mechanisms to detect and respond to any suspicious activities or tampering attempts.
  • Perform regular security assessments and penetration testing to identify and address any vulnerabilities in the application.

Compliant code​

package controllers

import play.api.mvc._
import javax.crypto.Mac
import javax.crypto.spec.SecretKeySpec
import org.apache.commons.codec.binary.Hex

class ApplicationController extends Controller {
  private val secretKey = "your-secret-key" // Replace with your actual secret key

  def checkRootUser = Action { implicit request =>
    val isRoot = request.headers.get("isRoot").getOrElse("false").toBoolean
    val signature = request.headers.get("signature").getOrElse("")

    if (isRoot && verifySignature(isRoot.toString, signature)) {
      Ok("Root user detected")
    } else {
      Ok("Regular user")
    }
  }

  private def verifySignature(data: String, signature: String): Boolean = {
    val hmacSha256 = Mac.getInstance("HmacSHA256")
    val secretKeySpec = new SecretKeySpec(secretKey.getBytes, "HmacSHA256")
    hmacSha256.init(secretKeySpec)

    val dataSignature = new String(Hex.encodeHex(hmacSha256.doFinal(data.getBytes)))
    dataSignature == signature
  }
}

The updated code now includes a method to verify the integrity of the application. This is done by using a HMAC (Hash-based Message Authentication Code) with SHA-256 to create a signature of the data (in this case, the isRoot value) using a secret key. This signature is then sent along with the data.

When the server receives the data and the signature, it uses the same secret key to generate a new signature from the received data. If the newly generated signature matches the received signature, it means that the data has not been tampered with during transmission.

This method ensures that even if an attacker is able to modify the isRoot value, they would not be able to generate the correct signature without knowing the secret key, thus preventing them from bypassing the root user check.

Please note that the secret key should be securely stored and kept secret. It should also be regularly rotated to further enhance the security of the application.

In addition, the application should implement other security controls as mentioned in the previous steps, such as secure coding practices, strong authentication and authorization mechanisms, secure communication protocols, input validation and sanitization, logging and monitoring mechanisms, regular updates and patches, and regular security assessments and penetration testing.

References​

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