@NodeHam said in Replacing header/user image with something else:
Therefore, I find what I've read hard to believe so thought I should ask here.
It's possible to perform something called Clickjacking, which is a malicious technique used by attackers to trick users into clicking on something different from what they perceive they are clicking on. Also known as UI redress attack or user interface (UI) deception attack, clickjacking involves overlaying an invisible layer over a legitimate webpage or interface element, such as a button or link. When the user interacts with what they see on the webpage, they are unknowingly interacting with the hidden elements, which could be links to malicious websites, downloading malware, or performing unwanted actions like giving access to personal information.
For instance, an attacker might overlay an invisible button over a "Download" button on a legitimate website. When a user tries to download something from the website, they unwittingly click the invisible button, triggering a download of malware instead.
Clickjacking attacks can be carried out through various means, including iframes, CSS opacity, or other web technologies. To protect against clickjacking, web developers can implement security measures like frame-busting scripts, X-Frame-Options HTTP header, or Content Security Policy (CSP) directives. Additionally, users should be cautious when interacting with unfamiliar or suspicious websites to avoid falling victim to clickjacking attacks.
As an example
<!DOCTYPE html>
<html>
<head>
<title>Clickjacking Example</title>
<style>
#overlay {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
opacity: 0; /* Make the iframe invisible */
z-index: 9999; /* Ensure it's above other content */
}
</style>
</head>
<body>
<h1>Welcome to Our Website!</h1>
<p>Click the button below to claim your prize:</p>
<button onclick="claimPrize()">Claim Prize</button>
<!-- Invisible iframe overlaying a legitimate website -->
<iframe id="overlay" src="https://legitimatesite.com"></iframe>
<script>
function claimPrize() {
// Code to handle claiming the prize goes here
alert("Congratulations! You've won a prize!");
}
</script>
</body>
</html>
Using relatively simple techniques, it's possible to inject malicious code into your own site. As you alluded to, securing using the correct headers is a good start, but if it were me, I'd avoid this altogether.