Rich data: the dark side to Web 2.0 applications

With great programming comes great responsibility


All web applications allow some form of rich data, but that rich data has become a key part of Web 2.0. Data is "rich" if it allows markup, special characters, images, formatting, and other complex syntax. This richness allows users create new and innovative content and services.

Unfortunately, richness affords attackers an unprecedented opportunity to bury attacks targeting users and systems downstream of the offending application or service supplier.

Even in the early days of Web 2.0, this is a huge problem: at least half the vulnerabilities that plague web applications and web services involve some form of injection.

The software industry already has a poor reputation for delivering software that doesn't work or contains security holes. Imagine how bad things will get in a world where people pick up vulnerabilities and hacks by connecting to dynamic web sites and "mashing up" applications.

Here are some things to bear in mind, to protect both your reputation and your users' systems and data.

Unscramble the egg

One of the oldest security principles in the book is you should always keep code and data separate. Once you mix them together, it's almost impossible separate them again. Unfortunately, most of the data formats and protocols we're using today mixing code and data like a bad DJ hashing up a cross fade. That's why injection is going to be with us for a long time.

HTML is one of the worst offenders. JavaScript code can be placed in a huge number of places with dozens of different forms and encodings - see the XSS cheatsheet for some examples. HTML allows JavaScript in the header, body, dozens of event handlers, links, CSS definitions, and style attributes.

There's no simple validation that can detect all the variants of code in all these places. However, you have to have a full security parser to validate HTML data before you can use it.

Untrusted data is code

Almost everything connected to the internet will execute data if an attacker buries the right kind of code in it. The code might be JavaScript, VB, SQL, LDAP, XPath, shell script, machine code or a hundred others depending on where that data goes.

SQL injection is just an attacker sneaking malicious SQL inside user inputs that gets concatenated into a query. Injected code isn't just a snippet anymore - it might be a huge program.

What's important to remember is that every piece of untrusted data - every form field, every URL parameter, every cookie, and every XML parameter - might contain injected code for some downstream system. If you're not absolutely sure there is no code in the data - and that's pretty much impossible - then for all you know, that data is really a little program. There is no such thing as plain old "data" anymore.

Next page: Chain-gang attack

Similar topics


Other stories you might like

  • Heart FM's borkfast show – a fine way to start your day

    Jamie and Amanda have a new co-presenter to contend with

    There can be few things worse than Microsoft Windows elbowing itself into a presenting partnership, as seen in this digital signage for the Heart breakfast show.

    For those unfamiliar with the station, Heart is a UK national broadcaster with Global as its parent. It currently consists of a dozen or so regional stations with a number of shows broadcast nationally. Including a perky breakfast show featuring former Live and Kicking presenter Jamie Theakston and Britain's Got Talent judge, Amanda Holden.

    Continue reading
  • Think your phone is snooping on you? Hold my beer, says basic physics

    Information wants to be free, and it's making its escape

    Opinion Forget the Singularity. That modern myth where AI learns to improve itself in an exponential feedback loop towards evil godhood ain't gonna happen. Spacetime itself sets hard limits on how fast information can be gathered and processed, no matter how clever you are.

    What we should expect in its place is the robot panopticon, a relatively dumb system with near-divine powers of perception. That's something the same laws of physics that prevent the Godbot practically guarantee. The latest foreshadowing of mankind's fate? The Ethernet cable.

    By itself, last week's story of a researcher picking up and decoding the unintended wireless emissions of an Ethernet cable is mildly interesting. It was the most labby of lab-based demos, with every possible tweak applied to maximise the chances of it working. It's not even as if it's a new discovery. The effect and its security implications have been known since the Second World War, when Bell Labs demonstrated to the US Army that a wired teleprinter encoder called SIGTOT was vulnerable. It could be monitored at a distance and the unencrypted messages extracted by the radio pulses it gave off in operation.

    Continue reading
  • What do you mean you gave the boss THAT version of the report? Oh, ****ing ****balls

    Say what you mean

    NSFW Who, Me? Ever written that angry email and accidentally hit send instead of delete? Take a trip back to the 1990s equivalent with a slightly NSFW Who, Me?

    Our story, from "Matt", flings us back the best part of 30 years to an era when mobile telephones were the preserve of the young, upwardly mobile professionals and fixed lines ruled the roost for more than just your senior relatives.

    Back then, Matt was working for a UK-based fixed-line telephone operator. He was dealing with a telephone exchange which served a relatively large town. "I ran a reasonably ordinary, read-only command to interrogate a specific setting," he told us.

    Continue reading

Biting the hand that feeds IT © 1998–2021