Cross Site Scripting in CSS Stylesheets

Cross Site Scripting in CSS Stylesheets

From the browser security handbook

The risk of JavaScript execution. As a little-known feature, some CSS implementations permit JavaScript code to be embedded in stylesheets. There are at least three ways to achieve this goal: by using the expression(...) directive, which gives the ability to evaluate arbitrary JavaScript statements and use their value as a CSS parameter; by using the url('javascript:...') directive on properties that support it; or by invoking browser-specific features such as the -moz-binding mechanism of Firefox.

... and after reading that, I find this on StackOverflow. See Using Javascript in CSS
In Firefox, you can use XBL to inject javascript in a page via CSS. However, the XBL file must reside in the same domain, now that bug 324253 is fixed.

There is another interesting (though different from your question) way to abuse CSS. See http://scarybeastsecurity.blogspot.com/2009/12/generic-cross-browser-cross-domain.html. Essentially, you misuse the CSS parser to steal content from a different domain.

Can XSS attacks be performed from within a linked stylesheet?

In Internet Explorer, Firefox and other browsers you can embed JavaScript in CSS by specifying a javascript: URL in a url() CSS statement.

Even if you manage to filter these out, an attacker can still completely redesign the page (including all of its textual content) with advanced CSS. Therefore, it becomes extremely easy to trick users to execute stupid actions, which is what XSS is about. For example, you could make the Delete Account button fill the entire window and change its text to "Click here to win 1000$".

You can white-list a select few properties (text-*, font-*, color, background (only colors and gradients, no URLs or other fancy stuff)), but you'll have to reject anything that does not match these restrictions.

Can Malicious Code Be Executed From A CSS File?

It can if they have access to modify. The below link describes xss and css (cross site scripting). They can redirect your background as one example

http://www.acunetix.com/websitesecurity/cross-site-scripting/

Cross Site Scripting Array Multiple Results

This is an update to the suggestion provided by "nobody"

The code provided was accurate except with the "." placement. Other than that, the code worked perfect.

Suggested:

<td>"htmlspecialchars(.$results['Date Saved'], ENT_QUOTES)."</td>

Correct Code:

<td>".htmlspecialchars($results['Date Saved'], ENT_QUOTES)."</td>

Complete Working Code:

 echo "<tr align='center' bgcolor='#0f7ea3'> 
    <td height='25px'>"
    .htmlspecialchars($results['Website'], ENT_QUOTES)."</td>
    <td>".htmlspecialchars($results['Keywords'], ENT_QUOTES)."</td>
    <td>".htmlspecialchars($results['Category'], ENT_QUOTES)."</td> 
    <td>".htmlspecialchars($results['Date Saved'], ENT_QUOTES)."</td>
    <td> <a href='" . htmlspecialchars($results['Website'], ENT_QUOTES) .       "'>Click To Access Your Link</a></td>
    </tr>" ;

Thank you so much.

---

Related Topics