Feeds

Cross-site hacks and the art of self defence

The new browser wars

Protecting users from Firesheep and other Sidejacking attacks with SSL

And what if you're at work or connected to the virtual private network? Your browser can go after the corporate portal. Do you have single sign-on? That means you're logged into every web application on your intranet, and your renegade browser can go after any of them.

Using CSRF, an attacker can attack all of these targets and can do just about anything you can do through your browser. All these attacks can be done remotely and basically anonymously.

Separate browsers

OK, so what can you do to protect yourself? First, don't stay logged into websites. You have to actually hit the log-out button, not just close the browser. Next, stop CSRF from getting to your critical websites by using a separate browser to access them. Companies are increasingly using separate browsers for accessing intranet applications and the internet - more should follow suit.

If your web application is attacked by a CSRF, all you'll see is normal transactions being performed by authenticated and authorised users. There won't be any way to tell that the user didn't actually execute the transaction. Probably the only way you'll find out that you have a CSRF problem is when users start complaining about phantom transactions on their account. The attacker can cover their tracks easily by removing the attack once it has worked.

Taken alone, CSRF attacks are simple and powerful. However, most attackers use CSRF and cross-site scripting (XSS) in conjunction. Together, these two techniques allow attackers to invade a victim's browser and execute malicious programs using the credentials of site the user is logged into.

This combination is devastating, and I'm frankly surprised that a cross-application CSRF-XSS worm hasn't already been developed.

The best solution to CSRF is to require a random token in each business function in your application. You can generate the random token when the user logs in and store it in their session. When you generate links and forms, simply add it to the URL or put it in a hidden form field. For example:

 

http://www.example.com?token=8FD41A&data=1

Requests that show up without the right token are forged and you can reject them. If you want to add protection without modifying code, the OWASP CSRFGuard is a filter that sits in front of your application and adds token support.

Whatever steps you take to protect yourself - whether it's the physical act of using different browsers or taking a token-based approach with the OWASP filter, make sure you do something - and soon. It will be difficult to roll out protection against forged requests once an attack has started.

Jeff Williams is the founder and CEO of Aspect Security and the volunteer chair of the Open Web Application Security Project. His latest project is the Enterprise Security API, a free and open set of foundational security building blocks for developers.

The next step in data security

More from The Register

next story
Israeli spies rebel over mass-snooping on innocent Palestinians
'Disciplinary treatment will be sharp and clear' vow spy-chiefs
Infosec geniuses hack a Canon PRINTER and install DOOM
Internet of Stuff securo-cockups strike yet again
THREE QUARTERS of Android mobes open to web page spy bug
Metasploit module gobbles KitKat SOP slop
'Speargun' program is fantasy, says cable operator
We just might notice if you cut our cables
Apple Pay is a tidy payday for Apple with 0.15% cut, sources say
Cupertino slurps 15 cents from every $100 purchase
YouTube, Amazon and Yahoo! caught in malvertising mess
Cisco says 'Kyle and Stan' attack is spreading through compromised ad networks
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
Greater dev access to iOS 8 will put us AT RISK from HACKERS
Knocking holes in Apple's walled garden could backfire, says securo-chap
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Security and trust: The backbone of doing business over the internet
Explores the current state of website security and the contributions Symantec is making to help organizations protect critical data and build trust with customers.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.