How to Investigate Phishing Websites with Redirection (2/5)

 

In our ongoing cybersecurity series, we are dissecting the redirection techniques often employed by phishing websites. In this post, we focus on Step 2: Recognizing Web Redirection Techniques. By understanding the various redirection methods in detail, you can better analyze and trace scam websites. This step covers:

• JavaScript-based redirects (e.g., using window.location.href)

• HTML Meta Refresh

• Iframe-based stealth redirects

• HTTP header 302 redirects (with examples in Flask and PHP)

• Bonus tactics used by attackers, including URL shorteners and device-based targeting

Below, we break down each of these techniques with examples, explanations, and best practices for detection.

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Recognizing Web Redirection Techniques

Understanding Automatic Page Redirects

In the coding realm, auto-redirecting a webpage is often implemented with just a few lines of code. Phishing sites commonly exploit these simple methods to transition users quickly to a different URL, often hiding the true target page from both security scanners and unsuspecting victims. Let’s explore the most common methods:

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1. JavaScript Auto-Redirection

How It Works:
JavaScript offers a straightforward way to redirect a webpage upon load. By manipulating the window.location.href property, attackers can force the browser to navigate to a predetermined URL.

Example Code:

html

<script>
  window.location.href = "https://line.me/yourgroup";
</script>

Explanation:
When the page loads, this script triggers an immediate redirect to the URL provided. Phishing sites employing this method, particularly on platforms using risky TLDs like .top, may redirect users in less than a second, making it hard to inspect the original content.

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2. HTML Meta Refresh

How It Works:
The meta refresh technique is one of the oldest redirection methods. It instructs the browser to redirect to a new URL after a specified time period.

Example Code:

html

<meta http-equiv="refresh" content="0; url=https://line.me/yourgroup">

Explanation:
In this example, the content="0" attribute indicates that the redirection happens instantly—0 seconds after the page loads. Phishers often use this method to deceive scanning bots while confusing human users, as it does not require JavaScript to be enabled on the browser.

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3. Iframe-Based Stealth Redirection

How It Works:
Rather than redirecting the entire page, an attacker can use an iframe to silently load external content. This technique can be combined with JavaScript-triggered actions to make it appear as though the user has been redirected.

Example Code:

html

<iframe src="https://line.me/yourgroup" style="display:none;"></iframe>

Explanation:
Here, the iframe is set to display: none;, which means it is not visible on the page. Though this is not a "redirect" in the conventional sense, it allows the attacker to load content from a malicious site in the background. This method can trick users into thinking the site is safe, while the dangerous content is quietly delivered via the hidden iframe.

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4. HTTP Header 302 Redirects

How It Works:
Server-side redirection using HTTP headers is another common method that avoids any front-end scripting or meta-based techniques. The server directly instructs the browser to move to a new URL.

Example Code (Python Flask):

python

from flask import redirect

@app.route("/")
def index():
    return redirect("https://line.me/yourgroup")

Example Code (PHP):

php

<?php
header("Location: https://line.me/yourgroup");
exit();
?>

Explanation:
In both examples, once the server receives a request, it immediately sends a 302 Found HTTP response along with a Location header pointing to the destination URL. The browser interprets this header and performs the redirection seamlessly—often so fast that users might not realize they have been rerouted from the original phishing page.

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5. Bonus: Advanced Attacker Tactics

Sophisticated phishing operations don’t stop at simple redirections. Cybercriminals may combine several tactics to obfuscate their tracks and further exploit targets:

• URL Shorteners:
  Using services like bit.ly or tinyurl, attackers can mask the original URL, making it harder to identify the destination and evade detection.

• Device-Based Targeting:
  Redirection logic may vary depending on the user's device or browser. For instance, the redirection may only occur for certain user agents, thereby sidestepping automated crawlers and security tools.

• Integration with Advertisements and Tracking:
  In some cases, the redirection includes additional parameters for Google Ads or Facebook tracking codes. This dual-purpose redirection not only reroutes users but also monetizes the scam by generating ad revenue through fraudulent clicks.

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Conclusion

Recognizing the various web redirection techniques is crucial for cybersecurity professionals and enthusiasts alike. By being able to identify JavaScript redirects, HTML meta refreshes, hidden iframe injections, and server-side HTTP header redirections, you can peel back layers of obfuscation used by phishing websites. Coupled with an awareness of advanced attacker tactics like URL shorteners and device-based targeting, you’re better equipped to conduct thorough phishing website investigations.

In the next installment of our series, we will dive deeper into practical analysis using tools like Chrome DevTools, offering a hands-on tutorial that builds upon the fundamental concepts covered in this post. Stay tuned to continue enhancing your cybersecurity skills and learn how to detect phishing websites 2025 effectively.