Windows DLL load hijacking exploits go wild

Computerworld - Less than 24 hours after Microsoft said it couldn't patch Windows to fix a systemic problem, attack code appeared Tuesday to exploit the company's software.

Also on Tuesday, a security firm that's been researching the issue for the past nine months said 41 of Microsoft's own programs can be remotely exploited using DLL load hijacking, and it named two of them.

On Monday, Microsoft confirmed reports of unpatched -- or zero-day -- vulnerabilities in a large number of Windows programs, then published a tool it said would block known attacks. At the same time, the company said it would not patch Windows because doing so would cripple existing applications.

Microsoft also declined to reveal whether any of its own applications contain bugs that attackers could exploit, saying only that it is investigating.

Many Windows applications don't call code libraries -- dubbed "dynamic-link library," or "DLL" -- using the full path name, but instead use only the file name, giving hackers wiggle room that they can then exploit by tricking an application into loading a malicious file with the same name as a required DLL.

If attackers can dupe users into visiting malicious Web sites or remote shares, 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.

By Tuesday, at least four exploits of what some call "binary planting" attacks -- and what others dub "DLL load hijacking" attacks -- had been published to a well-known hacker site. Two of the exploits targeted Microsoft-made software, including PowerPoint 2010, the presentation application in Office 2010, and Windows Live Mail, a free e-mail client bundled with Vista but available as a free download for Windows 7 customers.

Other exploits aimed at leveraging DLL load hijacking bugs in uTorrent and Wireshark, a BitTorrent client and network protocol analyzer, respectively.

At the same time, a Slovenian security company claimed that it reported bugs in two Microsoft-made programs last March.

"We're going to publish a list of the vulnerable apps we found sometime soon," said Mitja Kolsek, the CEO of Acros Security. "However, since HD Moore's tool kit is already being used for finding vulnerable apps and at this point hundreds of good and bad guys already know about it, I can say that the two we fully disclosed to Microsoft were in Windows Address Book/Windows Contacts and Windows Program Manager Group Converter."

HD Moore is the U.S. researcher who kicked off a small wave of DLL load hijacking reports last week when announced he had found 40 vulnerable Windows applications. On Monday, Moore published an auditing tool that others can use to detect vulnerable software. When combined with an exploit added that same day to Metasploit, the open-source hacking tool kit that Moore authored, the tool's results produce what he called a "point-and-shoot" attack.

All four of the exploits that went public Tuesday appear to be based on Moore's Metasploit attack code.

Although the Windows Address Book -- renamed Windows Contacts with the launch of Vista in 2007 -- may be familiar to users, Program Manager Group Converter is probably not, Kolsek admitted. But both can be exploited.

"They're part of every Windows installation and are associated with certain file extensions, allowing for 'double-click-bang' remote attacks," Kolsek said. "To increase the likelihood of success, an attacker can create a shortcut with a PDF or Word document icon pointing to such files, which otherwise have different, less familiar icons."

Contrary to Kolsek's claim, Program Manager Group Converter, a holdover from pre-Windows 95 days, is included with Windows XP, but not with Vista or Windows 7.

Altogether, Acros uncovered 121 remote execution vulnerabilities in 41 different Microsoft applications, but reported details of only the pair in Address Book/Contacts and Program Manager Group Converter. The rest were left for Microsoft's own researchers to find, said Kolsek.

Like a number of other companies, notably the French firm Vupen Security, Acros has decided that it will no longer report its vulnerability discoveries to vendors without compensation. "We've been giving them away for 10 years now," said Kolsek, "and it wasn't doing anything for us."

In a long post to a new Acros blog, Kolsek added that there was no bad blood between his company and Microsoft over the former's refusal to identify 119 bugs in the software vendor's products. "It was a mere incompatibility of business interests," he said.

Wireshark's lead developer, Gerald Combs, said today that a fix for the DLL load hijacking bug would be released in the next few days. Microsoft and BitTorrent, the firm responsible for uTorrent, did not reply to requests for comment about their patching plans.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com.

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