Need

Ensuring complete and secure code implementation

Context

• Usage of TypeScript for statically typed JavaScript development
• Usage of Express for building web applications and APIs

Description

Non compliant code

        import express from 'express';

const app = express();

app.get('/download', (req, res) => {
  const fileName = req.query.file;

  // Insecure code: serving binary file without checking for its source code
  res.sendFile(fileName);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});
        
        

The vulnerability in this code is that it serves binary files without checking for their corresponding source code. This means that any binary file can be requested and served by the server without any validation or verification.

This can lead to several security issues. Firstly, if the binary file is malicious in nature, it can potentially harm the server or the clients accessing it. Secondly, if the binary file contains vulnerabilities, it can be exploited by attackers to gain unauthorized access or perform other malicious activities.

Additionally, serving binary files without their corresponding source code can also result in code maintainability issues. Without the source code, it becomes difficult to understand and modify the functionality of the binary files, leading to potential bugs or security vulnerabilities going unnoticed.

To mitigate this vulnerability, it is recommended to include the source code of the binaries in the security analysis. This will help in determining the existence of vulnerabilities and ensure that the served binary files are safe and secure.

Steps

• Identify the binary files that are being served by the '/download' endpoint.
• Locate the corresponding source code for each binary file.
• Ensure that the source code for each binary file is secure and does not contain any vulnerabilities or sensitive information.
• Update the code to check for the existence of the source code before serving the binary file.
• If the source code for a binary file is not found or is determined to be insecure, consider removing the binary file from the server.
• Implement proper security measures to protect the binary files and prevent unauthorized access.
• Test the updated code to ensure that the binary files are served securely and without any vulnerabilities.

Compliant code

        import express from 'express';
import fs from 'fs';

const app = express();

app.get('/download', (req, res) => {
  const fileName = req.query.file;

  // Check if the source code for the binary file exists
  const sourceCodeExists = fs.existsSync(`source_code/${fileName}.js`);

  if (sourceCodeExists) {
    // Serve the binary file only if the corresponding source code exists
    res.sendFile(fileName);
  } else {
    // Handle the case when the source code is not found
    res.status(404).send('Source code not found for the requested file');
  }
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});
        
        

The fixed code is written in TypeScript and addresses the vulnerability related to incomplete functional code.

The code uses the Express framework to create a server. It imports the necessary modules, express and fs (file system), to handle HTTP requests and file operations, respectively.

The app object is created using the express() function.

The code defines a route for the /download endpoint using the app.get() method. This endpoint expects a query parameter called file which represents the name of the binary file.

Inside the route handler, the code checks if the corresponding source code for the binary file exists. It does this by using the fs.existsSync() method to check if the file exists in the source_code directory.

If the source code exists, the code sends the binary file using the res.sendFile() method. This ensures that the binary file is only served if the corresponding source code is available.

If the source code is not found, the code sends a 404 status code with a message indicating that the source code was not found for the requested file.

Finally, the server is started by calling the app.listen() method, which listens on port 3000. A console log message is printed to indicate that the server is running.

By including this code, the security analysis now checks for the existence of source code for the binaries before serving them. This helps to mitigate the risk of serving potentially malicious or vulnerable binary files.

References

• 233. Incomplete funcional code