Web services pose growing security risk

In their rush to implement Web services, some companies may be exposing themselves to new security risks that they may not fully understand, a security researcher said at the CanSecWest/core06 conference in Vancouver on Thursday.

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During a conference presentation, researcher Alex Stamos outlined how a number of Web services technologies, including the AJAX (Asynchronous JavaScript and XML) and the XQuery query language could be exploited by hackers to dig up secret information and attack systems.

Web services is a catch-all expression used to describe a form of distributed computing that uses standards based on XML (Extensible Markup Language) to simplify the job of programming software. One of its key tenets is that Web services applications are extremely portable and can easily interact with different types of software.

While this cross-platform capability can simplify programming, it can also create security risks by creating situations that may not have been anticipated by software developers, said Stamos, a founding partner of Information Security Partners, based in San Francisco. During his talk, he described an attack where a user could enter malicious code in a Web form and then get that code to run by calling up the company's customer service number and tricking a representative into inadvertently executing it.

Stamos also showed how Web services requests could be used to conduct denial of service attacks, either by creating malicious XML queries that used massive amounts of memory or by bombarding databases applications with more requests than they can handle.

Web application vendors have created tools that work like "magic," hiding complexity and making it very easy to create Web services. Unfortunately, these tools also make it easy for their users to ignore the security implications of the software they're building, Stamos said. "Because of all that magic pixie dust, the people who write Web services don't necessarily understand how they work," he said. "We have a lot of customers who are hanging unbelievably crazy functionality... just out on the Internet."

And hackers are catching on. Last month, security vendor Symantec issued its biannual Internet Security Threat report, noting that Web applications represent an increasingly attractive target for attackers. Of all vulnerabilities disclosed in the last six months of 2005, nearly 70 percent were associated with Web applications, Symantec said.

This trend is of particular concern to smaller companies that may not have the budgets to fully test the security of their software. But Stamos believes that Web application vendors could help out by adding input filtering capabilities to their products, to make them better able to tell when their software is being asked to do something that it shouldn't.

Security researchers also should be paying more attention to the issue, Stamos said. "We want to get more security people looking at Web services stuff," he said. "Web application security is the red-headed stepchild of the security industry."