7 Smart Ways to Prevent CRLF Injection in OpenCart

🛡️ What is CRLF Injection in OpenCart?

CRLF (Carriage Return Line Feed) Injection in OpenCart is a type of web application vulnerability that can allow attackers to inject special characters into HTTP headers, resulting in malicious manipulation of the response sent by the server. This can lead to HTTP response splitting, cross-site scripting (XSS), or even session fixation.

In OpenCart—an open-source e-commerce platform—this vulnerability usually arises when user input is improperly sanitized and directly passed to the response header or redirected URLs.

This blog will break down everything you need to know about CRLF Injection in OpenCart, supported by actionable examples, patching strategies, and even Website Vulnerability Scanner tools. ✅

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🔎 Why Is CRLF Injection Dangerous?

• Attackers can manipulate server responses.
• Malicious redirects can be added.
• XSS or phishing attacks can be executed.
• Log poisoning or cache poisoning may occur.

Example of a malicious CRLF payload:

%0d%0aContent-Length:%200

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🔥 How CRLF Injection Happens in OpenCart

OpenCart uses several components (routes, controllers, and views) where user input is often accepted without proper validation. CRLF Injection can be triggered in the redirect URLs, headers, and even email templates.

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⚠️ Coding Example 1: Vulnerable Header Redirect

// Controller in OpenCart
if (isset($this->request->get['redirect'])) {
    $redirect = $this->request->get['redirect'];
    header("Location: " . $redirect);
    exit;
}

Exploit:

An attacker could use the URL:

https://yourstore.com/index.php?route=account/login&redirect=%0d%0aSet-Cookie:%20sessionid=malicious

This injects a new HTTP header using %0d%0a (CRLF) and forces a malicious cookie.

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✅ Fix Example 1: Safe Header Redirect

// Validate and sanitize input
if (isset($this->request->get['redirect'])) {
    $redirect = filter_var($this->request->get['redirect'], FILTER_SANITIZE_URL);
    if (strpos($redirect, "\r") === false && strpos($redirect, "\n") === false) {
        header("Location: " . $redirect);
        exit;
    }
}

🧠 Pro Tip: Always sanitize and validate URLs before outputting them into headers.

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🛠️ Coding Example 2: Vulnerable Email Header Injection

$mail = new Mail();
$mail->setTo($this->request->post['email']);
$mail->setFrom('admin@yourstore.com');
$mail->setSubject("Order Confirmation");
$mail->send();

Exploit:

If the email field contains CRLF:

attacker@example.com%0d%0aBcc:victim@example.com

The attacker can BCC sensitive emails to themselves.

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✅ Fix Example 2: Email Validation

$email = filter_var($this->request->post['email'], FILTER_VALIDATE_EMAIL);

if ($email && !preg_match("/(\r|\n)/", $email)) {
    $mail = new Mail();
    $mail->setTo($email);
    $mail->setFrom('admin@yourstore.com');
    $mail->setSubject("Order Confirmation");
    $mail->send();
}

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📷 Screenshot: Free Vulnerability Scanner Tool

Use our Free Website Vulnerability Scanner online to instantly check your OpenCart site for CRLF and other injection vulnerabilities.

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🧪 Coding Example 3: Logging Injection

$log->write("Login from: " . $_GET['ip']);

Exploit:

http://yourstore.com/index.php?ip=127.0.0.1%0D%0ALogin%20Failed

This injects an extra log entry.

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✅ Fix Example 3: Sanitize IP Logging

$ip = preg_replace('/[^0-9\.]/', '', $_GET['ip']);
$log->write("Login from: " . $ip);

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🔍 Scan Results & Report

You can also generate a full vulnerability assessment report to check Website Vulnerability and keep track of your security findings.

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🔄 Internal & External Backlinks to Explore

To keep your application safe beyond CRLF Injection, here are some must-read articles and tools:

• 🔐 Fix Weak API Authentication in TypeScript ERP
• 🛡️ Prevent XSSI Attack in OpenCart
• 🛠️ Fix SSRF Vulnerability in Laravel Securely
• 🔍 OAuth Misconfiguration in OpenCart
• 📚 Explore All Security Blogs

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🚧 How to Prevent CRLF Injection in OpenCart

Here are 7 powerful ways to prevent CRLF injection:

1. Always sanitize user input with filter_var() and regex.
2. Validate redirect URLs before including them in headers.
3. Avoid reflecting user input in headers.
4. Use proper email validation when handling user input.
5. Escape special characters in logs and cookies.
6. Keep OpenCart and its extensions updated.
7. Use a vulnerability scanning tool regularly.

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💡 Final Thoughts

CRLF Injection in OpenCart is more than just a minor bug—it can be a gateway to full compromise. With real-world coding examples, fixes, and a free tool like ours for Website Security checks, you now have everything you need to secure your e-commerce store.

If you found this guide helpful, feel free to share it with your dev team or security community. And don’t forget to explore more useful content on our blog at pentesttesting.com/blog. 🚀

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