Best 7 Ways to Prevent Unvalidated Redirects and Forwards in TypeScript ERP

🔍 What Are Unvalidated Redirects and Forwards in TypeScript?

Unvalidated Redirects and Forwards are dangerous security flaws that allow attackers to manipulate redirection paths within an application. These vulnerabilities occur when an application accepts untrusted input to determine where a user should be redirected.

For instance, if a TypeScript-based ERP system allows users to be redirected after login, an attacker can manipulate the URL parameter to send them to a phishing or malicious website.

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🚨 How Attackers Exploit This Vulnerability?

Attackers typically exploit this issue in the following ways:

1. Phishing Attacks – Users are tricked into clicking a legitimate-looking link that redirects them to a malicious site.
2. Stealing Session Data – An attacker can redirect users to a fake login page and capture their credentials.
3. Bypassing Authentication – If an ERP application forwards users to restricted areas based on URL parameters, attackers may gain unauthorized access.

💡 Example of an Unsecure Redirect in TypeScript

const redirectTo = req.query.redirect;
res.redirect(redirectTo); // 🚨 This is dangerous! 🚨

If the application does not validate redirectTo, an attacker could exploit it with:

https://yourerp.com/login?redirect=http://malicious-site.com

Once the user logs in, they will be unknowingly redirected to an external phishing page controlled by the attacker.

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🛡️ 7 Best Ways to Prevent Unvalidated Redirects and Forwards in TypeScript ERP

To protect your ERP system, follow these seven security best practices with practical coding examples.

1️⃣ Restrict Redirects to a Whitelisted List of Domains

A simple yet effective way to prevent unvalidated redirects is to allow only trusted domains for redirections.

✅ Secure Redirection Using a Whitelist

const allowedDomains = ["https://yourerp.com", "https://dashboard.yourerp.com"];

function isValidRedirect(url: string): boolean {
  return allowedDomains.some(domain => url.startsWith(domain));
}

const redirectTo = req.query.redirect;
if (isValidRedirect(redirectTo)) {
  res.redirect(redirectTo);
} else {
  res.redirect("/error"); // Redirect to a safe error page
}

This method ensures that users can only be redirected to predefined safe destinations.

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2️⃣ Restrict Redirection to Internal Paths

Instead of accepting full URLs, allow only internal paths within your application.

✅ Secure Redirects Using Internal Paths

const redirectTo = req.query.redirect;
if (redirectTo && redirectTo.startsWith("/")) {
  res.redirect(redirectTo);
} else {
  res.redirect("/dashboard"); // Default safe redirect
}

🔒 This ensures users stay within the ERP system and prevents redirection to external sites.

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3️⃣ Sanitize and Encode User Input Before Redirection

Encoding user input prevents attackers from injecting malicious URLs into redirection parameters.

✅ Secure Encoding of Redirection Paths

import { URL } from "url";

function safeRedirect(req, res) {
  try {
    const redirectTo = new URL(req.query.redirect, "https://yourerp.com").pathname;
    res.redirect(redirectTo);
  } catch (error) {
    res.redirect("/error");
  }
}

This approach ensures only valid, internal paths are used and prevents external redirections.

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4️⃣ Use an Enum-Based Allow-Only List for Redirection

Instead of allowing dynamic user input, restrict redirects to an enum list of safe destinations.

✅ Secure Redirects Using an Enum List

enum SafeRoutes {
  Dashboard = "/dashboard",
  Profile = "/profile",
}

function secureRedirect(req, res) {
  const redirectTo = req.query.redirect as keyof typeof SafeRoutes;
  res.redirect(SafeRoutes[redirectTo] || SafeRoutes.Dashboard);
}

🔐 This prevents users from entering arbitrary URLs and ensures controlled redirection.

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5️⃣ Implement Middleware to Validate Redirects in Express.js

Middleware can act as an extra security layer to validate redirection requests before processing them.

✅ Express Middleware for Secure Redirects

import { Request, Response, NextFunction } from "express";

const allowedPaths = ["/dashboard", "/profile"];

function validateRedirect(req: Request, res: Response, next: NextFunction) {
  const redirectTo = req.query.redirect;
  if (allowedPaths.includes(redirectTo)) {
    next();
  } else {
    res.redirect("/dashboard"); // Default safe redirect
  }
}

// Apply Middleware
app.use("/redirect", validateRedirect);

🛠️ This ensures that only predefined redirect paths are allowed, blocking any untrusted inputs.

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6️⃣ Log and Monitor Suspicious Redirect Attempts

Logging helps track unauthorized redirect attempts and provides insight into potential security threats.

✅ Example: Logging Malicious Redirect Attempts

import fs from "fs";

function logRedirectAttempt(url: string) {
  fs.appendFileSync("redirect_logs.txt", `Suspicious redirect: ${url}\n`);
}

const redirectTo = req.query.redirect;
if (!allowedDomains.includes(redirectTo)) {
  logRedirectAttempt(redirectTo);
  res.redirect("/error");
}

📊 Logs help detect and mitigate security threats in real-time.

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7️⃣ Educate Users About Phishing Risks and Security Best Practices

Technical solutions alone cannot prevent all security threats—user awareness is equally important.

🛠️ Test Your ERP Security with Our Website Vulnerability Scanner

You can analyze your ERP system for vulnerabilities with our free website security checker. Check out the tool here:

Here’s an example of a website vulnerability assessment report generated by our tool to check Website Vulnerability:

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🔗 Related Cybersecurity Blog Posts

For more security insights, check out our latest articles:

• Prevent CSP Bypass in TypeScript ERP
• Prevent LDAP Injection in TypeScript ERP
• Is Your Phone Compromised? Signs of Malware
• More Cybersecurity Tips

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🚀 Final Thoughts: Strengthen TypeScript ERP Security

By following these seven security best practices and using our free tool for a Website Security test, you can effectively prevent Unvalidated Redirects and Forwards in TypeScript ERP and protect your users from phishing attacks and unauthorized redirections.

For a detailed guide on Business Logic Vulnerabilities in OpenCart, check out our in-depth analysis.

💡 Stay Secure & Keep Your ERP Safe! 🚀

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