Skip to main content

HTTP request smuggling

Need​

Consistent and secure processing of HTTP requests across all entities involved

Context​

  • Usage of Scala for building scalable and high-performance applications
  • Usage of play.api.mvc for handling HTTP requests and building web applications in Play Framework

Description​

Non compliant code​

import play.api.mvc._

class ApplicationController extends Controller {
  def processRequest = Action { request =>
    val data = request.body.asText.getOrElse("")
    // Process the data without proper validation
    val result = process(data)
    Ok(result)
  }
  
  def process(data: String): String = {
    // Simulate processing the data
    return "Processed: " + data
  }
}

This code is a simple example of a Play Framework controller in Scala. The processRequest action reads the body of the request as a text and passes it to the process function without any validation or sanitization. This is where the HTTP Request Smuggling vulnerability comes in.

In a real-world application, the process function might be parsing the request and interacting with the database or other parts of the system. If an attacker can smuggle a malicious request through the request body, it could lead to various security issues including unauthorized access, data corruption, and even system takeover.

The vulnerability arises because the system is not consistently processing HTTP requests. If a proxy, firewall, or any other entity processes HTTP requests differently than the server, it could lead to inconsistencies and security holes. For instance, an attacker could craft a request in such a way that the proxy sees two requests while the server sees only one. This could allow the attacker to bypass security measures and perform unauthorized actions.

To fix this vulnerability, the application should validate and sanitize all incoming requests. It should also use the same method to process requests as any other entities in the system. In addition, it should have measures in place to detect and handle malformed requests.

Steps​

  • Implement proper input validation and sanitization to ensure that the data received in the HTTP request is safe and does not contain any malicious content.
  • Use a consistent and secure method to parse and process the HTTP request body. Avoid relying on default or implicit parsing methods that may be vulnerable to HTTP request smuggling.
  • Ensure that the web server software and any intermediate entities, such as proxies or firewalls, are configured to handle HTTP requests consistently and securely.
  • Regularly update and patch the web server software and any other components involved in processing HTTP requests to mitigate known vulnerabilities.
  • Implement secure coding practices and follow security guidelines provided by the framework to minimize the risk of introducing vulnerabilities.

Compliant code​

import play.api.mvc._
import play.api.libs.json._

class ApplicationController extends Controller {
  def processRequest = Action(parse.json) { request =>
    request.body.validate[String].fold(
      errors => {
        BadRequest(Json.obj("message" -> "Invalid data format"))
      },
      data => {
        // Process the data after proper validation
        val result = process(data)
        Ok(result)
      }
    )
  }
  
  def process(data: String): String = {
    // Simulate processing the data
    return "Processed: " + data
  }
}

The updated code now includes proper input validation and sanitization. The HTTP request body is expected to be in JSON format and the data is validated as a string. If the validation fails, a BadRequest response is returned with a message indicating an invalid data format.

The Action(parse.json) is used to parse the HTTP request body. This ensures a consistent and secure method to parse and process the HTTP request body, reducing the risk of HTTP request smuggling.

It's important to note that the web server software and any intermediate entities, such as proxies or firewalls, should be configured to handle HTTP requests consistently and securely. Regular updates and patches should be applied to the web server software and any other components involved in processing HTTP requests to mitigate known vulnerabilities.

The code follows secure coding practices and adheres to security guidelines provided by the Play framework. This minimizes the risk of introducing vulnerabilities and helps ensure the security of the application.

References​

Last updated on