Feeds

No secret to stopping XSS and SQL injection attacks

Read, test, communicate, repeat

Internet Security Threat Report 2014

SQL injection attacks and cross-site scripting exploits just won't die.

The most recent and high-profile incident was a mass webpage attack on more than 100,000 pages, which included victims as diverse as The Wall Street Journal, TomTom, and the UK's Strathclyde police.

There was a teetering stack of exploits involved in this hit: cross-site scripting that involved a banner-ads module on top of IIS using ASP.net, and malicious JavaScript on the site that users were redirected to. The initial weakness that made this mass attack possible allowed a set of SQL injection exploits to be run against the targeted websites.

But none of it would have been possible if the sites involved had been more resilient to SQL injection attacks. This signals a lack of awareness among developers — but we shouldn't just be pointing the finger at them. The problem also comes back to a lack of awareness among testers, who really should be actively testing applications for common security holes as a matter of course.

But the problem goes even deeper than that. The current emphasis on unit testing among developers has produced a myopic attitude to testing, in which integration testing — which would help to expose certain security flaws — is seen as too troublesome to bother with.

The frustrating thing about SQL injection attacks in particular, though, is that they're so easy to prevent in the first place — and easy to test for, of course.

Take the following query. Let's say we run a travel website where somebody searches for hotels in Blackpool. The query, constructed in your server code, would look something like:

SELECT * FROM hotels WHERE city = 'Blackpool';

In the search form, the user would enter a town/city. The server component extracts this value from the submitted form, and places it directly into the query.

Giving effectively free access to the database opens up all sorts of potential for sneaky shenanigans from unscrupulous exploiters. All the user has to do is add their own closing single-quote in the search form, plus some additional gubbins to turn it into a valid query:

Blackpool'; --

Everything after the -- is treated as a comment, so the door to your data is now wide open. How about if the user types into the search form:

Blackpool'; DROP TABLE hotels; --

Your server-side code will faithfully construct this into the following SQL, and pass it straight to the database, which in turn will chug away without question, just following orders:

SELECT * FROM hotels WHERE city = 'Blackpool'; DROP TABLE hotels; --';

Depending how malicious the attacker is, they could wreak all sorts of havoc or (worse, in a way) build on the "base exploit" to extract other users' passwords from the database. There's a good list of SQL injection examples here.

Choosing a cloud hosting partner with confidence

More from The Register

next story
Netscape Navigator - the browser that started it all - turns 20
It was 20 years ago today, Marc Andreeesen taught the band to play
Sway: Microsoft's new Office app doesn't have an Undo function
Content aggregation, meet the workplace ... oh
Sign off my IT project or I’ll PHONE your MUM
Honestly, it’s a piece of piss
Return of the Jedi – Apache reclaims web server crown
.london, .hamburg and .公司 - that's .com in Chinese - storm the web server charts
NetWare sales revive in China thanks to that man Snowden
If it ain't Microsoft, it's in fashion behind the Great Firewall
Chrome 38's new HTML tag support makes fatties FIT and SKINNIER
First browser to protect networks' bandwith using official spec
Admins! Never mind POODLE, there're NEW OpenSSL bugs to splat
Four new patches for open-source crypto libraries
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.