A minor theme in my recent B-Sides SF presentation was the stagnancy of innovation since HTML4 was finalized in December 1999. New programming patterns have emerged since then, only to be hobbled by the outmoded spec. To help recall that era I scoured archive.org for ancient curiosities of the last millennium – like Geocities’ announcement of 2MB (!?) of free hosting space.

One appsec item I came across was this Netscape advisory regarding a Java bytecode vulnerability – in March 1996.

March 1996 Java Bytecode Vulnerability

Almost twenty years later Java still plagues browsers with continuous critical patches released month after month after month, including the original date of this post – March 2013.

Java’s motto

Write once, run anywhere.

Java plugins

Write none, uninstall everywhere.

The primary complaint against browser plugins is not their legacy of security problems, although it’s an exhausting list. Nor is Java the only plugin to pick on. Flash has its own history of releasing nothing but critical updates. The greater issue is that even a secure plugin lives outside the browser’s Same Origin Policy (SOP).

When plugins exist outside the expected security and privacy controls of SOP and the DOM, they weaken the browsing experience. Plugins aren’t completely independent of these controls, their instantiation and usage with regard to the DOM still falls under the purview of SOP. However, the ways that plugins extend a browser’s network and file access are rife with security and privacy pitfalls.

For one example, Flash’s Local Storage Object was easily abused as an “evercookie” because it was unaffected by clearing browser cookies and whether browsers were configured to accept cookies or not. Even the lauded HTML5 Local Storage API could be abused in a similar manner. It’s for reasons like these that we should be as diligent about demanding privacy fixes as much as we demand security fixes.

Unlike Flash, the HTML5 Local Storage API is an open standard created by groups who review and balance the usability, security, and privacy implications of features intended to improve the browsing experience.

Creating a feature like Local Storage and aligning it with similar security controls for cookies and SOP makes them a superior implementation in terms of preserving users’ expectations about browser behavior. Instead of one vendor providing a means to extend a browser, browser vendors (the number of which is admittedly dwindling) are competing to implement a uniform standard.

Sure, HTML5 brings new risks and preserves old vuln in new and interesting ways, but a large responsibility for those weaknesses lies with developers who would misuse an HTML5 feature in the same way they might have misused AJAX in the past.

Maybe we’ll start finding poorly protected passwords in Local Storage objects, or more sophisticated XSS exploits using Web Workers or WebSockets to exfiltrate data from a compromised browser. Security ignorance takes a long time to fix. Even experienced developers are challenged by maintaining the security of complex apps.

HTML5 promises to make plugins largely obsolete. We’ll have markup to handle video, drawing, sound, more events, and more features to create engaging games and apps. Browsers will compete on the implementation and security of these features rather than be crippled by the presence of plugins out of their control.


Getting rid of plugins makes our browsers more secure, but adopting HTML5 doesn’t imply browsers and web sites become secure. There are still vulns that we can’t fix by simple application design choices like including X-Frame-Options or adopting Content Security Policy headers.

Would you click on an unknown link – better yet, scan an inscrutable QR code – with your current browser? Would you still do it with multiple tabs open to your email, bank, and social networking accounts?

You should be able to do so without hesitation. The goal of appsec, browser developers, and app owners should be secure environments that isolate vulns and minimize their impact.

It doesn’t matter if “the network is the computer” or an application lives in the cloud or it’s something as a service. It’s your browser that’s the door to web apps and, when it’s not secure, an open window to your data. Getting rid of plugins is a step towards better security.