Web Cache Deception Attack in TypeScript-Based ERP

In today’s fast-paced digital infrastructure, TypeScript-based ERP (Enterprise Resource Planning) systems are rapidly becoming the go-to choice for enterprises due to their scalability, maintainability, and strong typing system. However, while developers focus on functionality, they often overlook one silent but deadly vulnerability: Web Cache Deception (WCD).

In this blog post, we’ll walk through how Web Cache Deception attacks work, why they are dangerous in TypeScript ERP systems, how to detect and prevent them, and we’ll show you real-world coding examples to fix the issue like a pro.

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📌 What is Web Cache Deception?

Web Cache Deception is a technique that exploits caching behavior to expose private or authenticated data to unauthenticated users. It was first introduced by security researcher Omer Gil, and it has since become a frequently overlooked vulnerability, particularly in modern single-page applications (SPAs) and REST-based ERPs.

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🧨 How Web Cache Deception Works in TypeScript ERP

Most ERP systems leverage dynamic routes and serve sensitive data based on authenticated sessions. If these dynamic routes are accidentally cached, attackers can access cached content—often including confidential details like:

• Personal user data
• API keys
• Billing and invoice information
• Configuration files

Consider this route in a TypeScript-based Express ERP:

app.get('/dashboard', authenticateUser, (req, res) => {
    res.send(renderDashboard(req.user));
});

If there’s no caching policy set, and an attacker visits:

https://erp.example.com/dashboard/evil.js

Then CDN or reverse proxies (like Varnish, Squid, or even Cloudflare) may mistake this as a static asset due to the .js extension and cache it.

Next time, even an unauthenticated visitor may retrieve a cached dashboard intended for another user.

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🎯 Why TypeScript-Based ERP Systems Are Especially at Risk

ERP applications often:

• Use custom routing logic with shared route handlers
• Integrate frontend bundlers (like Webpack) that don’t validate user-access paths
• Rely on CDNs or reverse proxies to optimize performance
• Assume caching is handled securely by the platform or framework

However, security is a shared responsibility between app logic, headers, and network layers.

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💻 Common Code Pitfall (Without Cache-Control)

app.get('/account/settings', authenticateUser, (req, res) => {
    const settings = getUserSettings(req.user.id);
    res.send(settings);
});

If no Cache-Control headers are added, and if the CDN caches this route due to a crafted URL like:

/account/settings/malicious.css

Then private user settings can be cached and exposed.

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🛠️ How to Prevent Web Cache Deception Attack in TypeScript ERP

Let’s break it down into actionable points with examples.

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✅ 1. Set Proper Cache-Control Headers

Code Example:

app.use((req, res, next) => {
    if (req.isAuthenticated()) {
        res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
    } else if (req.url.match(/\.(css|js|png|jpg)$/)) {
        res.setHeader('Cache-Control', 'public, max-age=31536000, immutable');
    } else {
        res.setHeader('Cache-Control', 'private, no-cache');
    }
    next();
});

🧠 Explanation:
Ensure that dynamic pages are never cached, and only static assets are explicitly whitelisted.

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✅ 2. Validate and Sanitize All URL Routes

Attackers rely on injecting fake extensions to trick the cache. Block them!

app.use((req, res, next) => {
    const forbiddenExtensions = /\.(css|js|jpg|png|html)$/;
    if (req.isAuthenticated() && forbiddenExtensions.test(req.url)) {
        return res.status(400).send("Malformed request.");
    }
    next();
});

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✅ 3. Avoid User-Specific Data in Cacheable Routes

Never include user-specific or session-based content in public URLs.

❌ Bad:

app.get('/user/:id/profile', ...);

✅ Better:

app.get('/user/profile', authenticateUser, ...);

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✅ 4. Force ‘Vary: Cookie’ Header

Tell cache systems to differentiate responses based on session cookies.

res.setHeader('Vary', 'Cookie');

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✅ 5. Configure CDN Rules to Bypass Caching for Sensitive Paths

In Cloudflare (or similar), add rules:

If URL Path contains /dashboard OR /account
→ Cache Level: Bypass

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✅ 6. Use Whitelisting Over Blacklisting

Only allow specific safe static paths to be cached:

const cacheablePaths = ['/logo.png', '/main.js', '/styles.css'];

app.use((req, res, next) => {
    if (cacheablePaths.includes(req.path)) {
        res.setHeader('Cache-Control', 'public, max-age=86400');
    } else {
        res.setHeader('Cache-Control', 'no-store');
    }
    next();
});

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✅ 7. Monitor and Detect Suspicious URLs

Create logging to catch suspicious access attempts:

if (req.url.includes('.css') || req.url.includes('.js')) {
    console.warn(`Potential cache deception attempt: ${req.url}`);
}

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🔍 Detecting Cache Vulnerabilities Automatically

You don’t need to do it all manually. Use our Website Vulnerability Scanner tool to scan for vulnerable cache configurations in your ERP system.

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📸 Screenshot Placeholder 1

Easily scan your TypeScript ERP using our Free Website Security Scanner for Web Cache Deception vulnerabilities.

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📸 Screenshot Placeholder 2

An auto-generated report showing exposed cache routes to check Website Vulnerability.

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🔗 Related Reading and Internal Backlinks

To strengthen your ERP system’s defenses, check out our other technical blogs:

• 💉 Prevent XML Injection in TypeScript
• 🧱 Prevent JWT Attacks in TypeScript ERP
• 🧪 Prevent Cache Poisoning in TypeScript
• ☁️ Vulnerability Assessment of CloudBank
• 📖 Browse all at our Cybersecurity Blog

Want to secure your OpenCart-based eCommerce platform? Visit our sister site:
👉 Prevent XML Injection in OpenCart

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🚀 Final Thoughts

Web Cache Deception can cause serious data leaks—especially in complex ERP systems built with TypeScript. With user sessions, API-driven dynamic content, and caching proxies in place, developers must be vigilant about how their apps behave under caching layers.

🔐 Action Items:

• Set appropriate Cache-Control headers
• Whitelist static assets explicitly
• Block suspicious URL patterns
• Use our Free Security Testing Tool to evaluate your system today

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