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Automatic information enumeration

Need​

Prevention of automatic information enumeration and unauthorized access

Context​

  • Usage of Scala for building scalable and functional applications
  • Usage of play.api.mvc for handling HTTP requests and responses in Play Framework
  • Usage of global execution context for Scala concurrent programming
  • Usage of scala.concurrent.Future for asynchronous programming in Scala

Description​

Non compliant code​

import play.api.mvc._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future

class HomeController @Inject()(val controllerComponents: ControllerComponents) extends BaseController {

  def getSystemInfo = Action.async {
    Future {
      val runtime = Runtime.getRuntime
      val process = runtime.exec("netstat -tuln")
      val output = scala.io.Source.fromInputStream(process.getInputStream).mkString
      Ok(output)
    }
  }
}

The above Scala code is a Play Framework controller that includes a method getSystemInfo. This method when invoked, runs a netstat -tuln command on the system where the application is hosted. The netstat -tuln command lists all active Internet connections for the system, including the listening ports.

The output of the command, which includes information about all open ports and services, is then returned in the HTTP response. This is a serious security vulnerability as it exposes sensitive system information to any client that can send a request to this endpoint.

In addition, this code is vulnerable to command injection as the command to be executed is hardcoded and could be replaced with a malicious command.

The information leakage can be used by an attacker for reconnaissance before launching other more serious attacks. For example, knowing which ports are open can help an attacker identify potential points of entry into the system.

The command injection vulnerability can allow an attacker to execute arbitrary commands on the system, potentially leading to full system compromise.

Steps​

  • Avoid executing system commands directly from the application code.
  • Implement proper input validation and sanitization to prevent command injection attacks.
  • Use secure APIs or libraries to retrieve system information instead of executing shell commands.
  • Ensure that only authorized users have access to sensitive system information.
  • Implement proper access controls and authentication mechanisms to protect against unauthorized access.
  • Regularly update and patch the application and its dependencies to address any security vulnerabilities.

Compliant code​

import play.api.mvc._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future

class HomeController @Inject()(val controllerComponents: ControllerComponents) extends BaseController {

  def getSystemInfo = Action.async {
    Future {
      // Removed the system command execution
      Ok("System Information")
    }
  }
}

The original code was vulnerable because it was executing a system command (netstat -tuln) directly from the application code. This is a security risk because it can lead to automatic information enumeration, where an attacker could potentially gain access to sensitive system information such as open ports and available services.

The fixed code removes the system command execution. Instead, it simply returns a placeholder string ("System Information"). In a real-world application, you would replace this with a secure method of retrieving the required system information.

In addition to this code fix, you should also implement the following security measures:

  • Input validation and sanitization: This can help prevent command injection attacks, where an attacker manipulates input data to execute arbitrary commands on the system.

  • Use of secure APIs or libraries: Instead of executing system commands directly, use secure APIs or libraries that provide the required functionality in a safe manner.

  • Access controls and authentication: Ensure that only authorized users have access to sensitive system information. Implement robust access controls and authentication mechanisms to protect against unauthorized access.

  • Regular updates and patches: Regularly update and patch the application and its dependencies to address any security vulnerabilities. This can help protect against known vulnerabilities that could be exploited by attackers.

References​

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