Finding a Way InBy Lisa Vaas | Posted 2007-04-02 Email Print
A pervasive vulnerability that allows an attacker to take over any Web browser and silently intercept sensitive data input occurs in Web 2.0 settings from Yahoo to ASP .Net to Google, security firm Fortify says.
One problem with JSON is that CSRF (cross-site request forgery) allows attackers to bypass the technology's cookie-based authentication, as DRW's creator, Walker, says in his blog.
Specifically, CSRF allows a user to invoke cookie-protected actions on a remote server, thus allowing "Mr. Evil to trick Mrs. Innocent into transferring money from her bank account into his," Walker wrote.
Walker is a developer and runs a consultancy called Getahead.
"I believe that JSON is unsafe for anything but public data unless you are using unpredictable URLs," he said in the same blog posting.
And more details from the Fortify paper:
Anywhere this vulnerability can occur, it does occur, Chess said, with the exception of in DWR. As for the major companies behind frameworks, most all said they will work on the vulnerability and that it will be fixed in the next version.
Microsoft, for one, told eWEEK that its MSRC is on this and that the company is investigating new public reports of possible vulnerabilities that occur in applications developed using the downloadable Microsoft ASP.NET AJAX framework.
A Microsoft spokesperson said that the company is not aware of any attacks attempting to use the reported issue or of customer impact at this time. Yahoo had not been able to provide comment by the time this story posted.
Google, for its part, has posted an article that shows developers how to prevent the vulnerabilities described by Fortify in all versions of the Google Web Toolkit.
"We plan to add additional, automatic safeguards in the next version of GWT, due out in the coming weeks, to supplement the security measures developers take on their own," a Google spokesperson added.
These companies have been through the security flaw grinder and know better than to ignore vulnerabilities, Chess said. The problem is that many developers aren't using frameworks from the big players at allrather, they're rolling their own. Unfortunately, many such developers haven't yet embraced security as their responsibilityand it's this that's prompted Fortify to start banging the drum on the issue.
"Most people don't know when they use these AJAX-style components [i.e., frameworks] that they're at more risk," Chess said. "We need to talk to the AJAX community about what the problem is and what they have to do to address it."
The overwhelming reaction Fortify received from framework maintainers was that this vulnerability is a high-priority fix, Chess said.
What's surprising is the few instances in which framework developers said that security wasn't their problem.
"It makes me really mad to think there are developers out there who are fielding code and who expect people who are going to use that code to figure out all the security ramifications," Chess said.
Chess declined to name names, given that he's still working with them, trying to get recalcitrant developers to address the vulnerability.
The Array format is fairly commonly used and makes it easy to trick the browser, Chess said. Exploiting the vulnerability is all about having the conditions necessary to abuse the security policy implemented by a given Web browser. Unfortunately, Fortify found those conditions are fulfilled "a surprising amount of time," he said.
The problem with getting developers to accept responsibility for fixing the vulnerability is easy to spot after comparing AJAX hijacking to, say, buffer overflows, Chess said.
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