Evil PDF Exploiting Windows-IE Flaw in the Wild

 
 
By Lisa Vaas  |  Posted 2007-10-23 Print this article Print
 
 
 
 
 
 
 

A malicious PDF is exploiting a URL-handling flaw in Windows XP and Windows Server 2003 running IE7.

A PDF Trojan horse is spreading malware by exploiting a URL-handling vulnerability in Windows XP and Windows Server 2003 running Internet Explorer 7, Symantec warned customers of its DeepSight Alert Services on Oct. 23. On Oct. 10, Microsoft released Security Advisory 943521 about this vulnerability and public reports of remote code execution. At the time, it said a patch was in the works. The vulnerability is caused by insufficient validation of URLs. Attackers can leverage the flaw to execute arbitrary commands via maliciously crated URLs.
Symantec noted in its advisory that the issue was originally disclosed in July but initially received scant attention. In light of new research, public exploits and Microsofts advisory, Symantec considers the problem to be more severe.
"With the ease of exploitation, the availability of public proof-of-concept code, and further attention that this vulnerability is receiving, we will likely begin to see more exploitation of this issue in the wild," the company, based in Cupertino, Calif., said in its advisory. Symantec is calling the malware Trojan.Pidief.A. The rigged PDF file is using the "mailto: option" vulnerability to install a Trojan that in turn is downloading a file that the security firm is detecting as "Downloader." That document is delivered as a piece of spam with a file name such as "BILL.pdf" or "INVOICE.pdf." Upon execution, the malicious code attempt to disable the Windows Firewall with a "netsh firewall set opmode mode=disable" command, and then downloads a remote file via FTP from 81.95.146.130. Symantec says the remote file is "ldr.exe" and is a Downloader Trojan. As of the afternoon of Oct. 23 when Symantec posted its advisory, the host 81.95.146.130 was alive and still serving "ldr.exe" over FTP. "This server is known for hosting malicious software," Symantec warned. Click here to read about why small and midsize businesses are sitting ducks for cyber-crime. The DeepSight Threat Analyst Team is advising users to block delivery of PDF files in e-mail. The team is also advising organizations to tell employees not to read or execute PDF files from unknown or untrusted sources. In addition, Symantec is advising users and companies to block access to the network and IP address involved in this attack, as given above, and to apply the patches outlined in Adobe Advisory APSB07-18 as soon as possible. Adobe released fixes on Oct. 22. In lieu of providing a timetable for the delivery of a patch, Mark Miller, director of Security Response Communications for Microsoft, headquartered in Redmond, Wash., issued a statement explaining that creating security updates is complicated. "Once the MSRC knows the extent and the severity of the vulnerability, it works to develop an update for every supported version affected. Once the update is built, it must be tested with the different operating systems and applications it affects, then localized for many markets and languages across the globe. In some instances, multiple vendors are affected by the same or similar issues, which require a coordinated release," Miller said. Check out eWEEK.coms Security Center for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at eWEEKs Security Watch blog.
 
 
 
 
Lisa Vaas is News Editor/Operations for eWEEK.com and also serves as editor of the Database topic center. Since 1995, she has also been a Webcast news show anchorperson and a reporter covering the IT industry. She has focused on customer relationship management technology, IT salaries and careers, effects of the H1-B visa on the technology workforce, wireless technology, security, and, most recently, databases and the technologies that touch upon them. Her articles have appeared in eWEEK's print edition, on eWEEK.com, and in the startup IT magazine PC Connection. Prior to becoming a journalist, Vaas experienced an array of eye-opening careers, including driving a cab in Boston, photographing cranky babies in shopping malls, selling cameras, typography and computer training. She stopped a hair short of finishing an M.A. in English at the University of Massachusetts in Boston. She earned a B.S. in Communications from Emerson College. She runs two open-mic reading series in Boston and currently keeps bees in her home in Mashpee, Mass.
 
 
 
 
 
 
 

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