ActiveX security faces storm before calm
MS responds to more Moore flaws
HD Moore is at it again.
Using a custom-built data fuzzing tool, the security researcher pinpointed more than 100 vulnerabilities in the ActiveX controls included with the default installation of Microsoft's Windows XP operating system.
Data fuzzing tools combine knowledge of the input parameters accepted by a software package with a tenacious and systematic mangling of the data to discover how applications react to various permutations, whether valid or invalid.
Moore claims that, while he found more than 100 vulnerabilities in standard ActiveX components, almost another 100 exist in the ActiveX components installed by popular applications, such as Microsoft Office.
While most of the issues discovered by Moore, who is also the founder of the Metasploit Project, are simple denial-of-service problems, about a dozen are remotely exploitable issues in ActiveX controls for Internet Explorer, he said.
"There are a couple of classes that have so many vulnerabilities that I had to black list the entire class," Moore said.
The research underscores the security problems posed by ActiveX controls. ActiveX allows websites to add interactivity and greater functionality to a visitor's browsing experience. However, because the technology allows the website to affect changes on a visitor's PC, the technology also poses a danger.
Online criminals frequently use flaws in ActiveX to install malicious code on victim's browsers. One tool - known as WebAttacker and sold from a Russian website for about $20 - has had great success compromising victims' computers via a flaw in Microsoft's Data Access Components, an ActiveX component fixed in April by Microsoft. The success rate for the tool using that flaw is between 12 per cent and 15 per cent, said Dan Hubbard, vice president of internet security firm Websense.
"People simply aren't updating their browsers," Hubbard said. "Old exploits still work, and on the new exploit front, you can hit a home run with something that works on every browser. The bad guys are getting better at what they are doing."
ActiveX started life as the Object Linking and Embedding (OLE) features created in 1990 to allow Windows applications to exchange data. The general framework became the Component Object Model in 1993 - now known as the Distributed Component Object Model (DCOM)- while Microsoft renamed OLE 2.0 as ActiveX and pushed web developers to add more interactivity to their sites using the technology.
Yet, the software components act as a gateway through which websites can interact with visitors' PCs. And using data-fuzzing tools, finding flaws in key ActiveX components is not difficult. Using such tools, Metasploit's Moore has found enough browser flaws to release a vulnerability every day throughout the month of July.
Moore separated his work analysing ActiveX for flaws because he created the tool himself and he wanted to give Microsoft a chance to fix the issues before releasing the fuzzer, he said.
"You have to really know what you're fuzzing for to cover all the possible vulnerabilities," Moore said.
A major problem with ActiveX is that the components, especially those accessible through Internet Explorer, place the PC's user in a critical role as gatekeeper for the security of the system. While other models, such as Java, may allow for less interactivity and cool features, they deemphasise the users security role, Websense's Hubbard said.
"ActiveX passes the security process to the end user, as opposed to being handled within the language," he said. "In Java, there are certain things that you can't do, as opposed to ActiveX, which allows you to do them, if the users says OK."
The result is that many security-conscious system administrators and users shy away from the software. Source-code security firm Fortify, which looks to its customers for where to focus its efforts, has rarely looked at ActiveX because its customers are wary of the security problems posed by the software.
To minimise the danger of attack in the future, Microsoft plans to disable by default all but the most commonly used ActiveX controls in its coming browser, Internet Explorer 7. Moreover, the company will also use more informative warnings to users before allowing them to install new ActiveX controls, a feature the software giant calls ActiveX Opt-in.
"ActiveX Opt-in removes the default ability for malicious websites to load any ActiveX control as a means to attack a system," Microsoft said in a statement sent to SecurityFocus. "When a website attempts to load a control IE has never used before, the information bar will be displayed to advise the users a trust decision is required."
The software giant said that users who want more security now can upgrade to the third beta version of IE 7. The final version will be pushed out as a high-priority update via the company's Automatic Updates distribution channel in the fourth quarter of this year. Users will be notified that the update is available can can make a choice of whether to download it. Microsoft is also making a policy tool available for companies that want to block the notification to employees.
Upgrading to Internet Explorer 7 will require that the Windows user authenticate their system using Microsoft's Windows Genuine Advantage antipiracy tool.
The security improvements in Internet Explorer will make the latest flaws found by Metaploit's Moore go away, the security researcher said.
"Assuming everyone switches to IE 7, the easiest way to load ActiveX controls go away," he said. "So these issues pretty much go away with Internet Explorer 7."
This article originally appeared in Security Focus.
Copyright © 2006, SecurityFocus