Unpatched DLL bugs let hackers exploit Windows 7 and IE9, says researcher

Although Microsoft has patched multiple DLL load hijacking vulnerabilities since last summer, Windows and Internet Explorer 9 (IE9) can still be exploited, a security company warned today.

Microsoft confirmed that it's investigating the claims by Slovenia-based Acros Security.

Researchers from Acros will demonstrate the new attacks at the Hack in the Box security conference in Amsterdam later this month.

"We'll reveal how IE8 and IE9 can be used on Windows 7, Vista and XP for attacking users without any security warnings, even in 'Protected mode,' and how to remotely make many seemingly-safe applications, for example, Word 2010 and PowerPoint 2010, vulnerable," said Acros CEO Mitja Kolsek in a Friday email.

The attack class called "DLL load hijacking" by some, but dubbed "binary planting" by Acros, jumped into public view last August when HD Moore, the creator of the Metasploit penetration hacking toolkit and chief security officer at Rapid7, found dozens of vulnerable Windows applications. Moore's report was followed by others, including several from Kolsek and Acros.

Many Windows applications don't call DLLs using a full path name, but instead use only the filename, giving hackers a way to trick an application into loading a malicious file with the same title as a required DLL. If attackers can dupe users into visiting malicious Web sites or remote shared folders, or get them to plug in a USB drive -- and in some cases con them into opening a file -- they can hijack a PC and plant malware on it.

Since Moore's original report, Microsoft has issued 13 DLL load hijacking-related updates stretching from November 2009 to last month, when it patched a pair in Office and Visual Studio as part of a massive 64-fix update.

But the Redmond, Wash. developer has not closed all the holes in its software, said Kolsek today.

In a blog post, Kolsek outlined still-available DLL load hijacking attack vectors, including one that works against any copy of Windows XP, another that can be used to compromise PCs running the newer Vista or Windows 7 operating systems, and a third that can be exploited through Internet Explorer 9 (IE9), Microsoft's eight-week-old browser.

At Hack in the Box, Kolsek intends to demonstrate exploits of DLL load hijacking bugs in Windows using malicious Word 2010 and PowerPoint 2010 documents, and against IE9.

The IE9 attack works even on Windows 7, where the browser runs in a "sandbox" of sorts, an anti-exploit technology designed to block hackers from infecting a PC. "[The attack works] against Internet Explorer 9 in protected mode on Windows 7 ... without any suspicious double-clicks or security warnings," Kolsek wrote on the Acros blog.