Adobe PDF Software Flaw Found
Computer security researchers said Wednesday they have discovered a vulnerability
in Adobe Systems Inc.'s ubiquitous Acrobat Reader software that allows cyber-intruders
to attack personal computers through trusted Web links.
Virtually any Web site hosting Portable Document Format, or PDF, files are
vulnerable to attack, according to researchers from Symantec Corp. and VeriSign
Inc.'s iDefense Intelligence.
The attacks could range from stealing cookies that track a user's Web browsing
history to the creation of harmful worms, the researchers said.
The flaw, first revealed at a hacker conference in Germany over the holidays,
exists in a plug-in that enables Acrobat users to view PDF files within Web
By manipulating the Web links to those documents, hackers and online thieves
are able to commandeer the Acrobat software and run malicious code when users
attempt to open the files, according to Ken Dunham, director of the rapid response
team at VeriSign's iDefense Intelligence.
Dunham gave this hypothetical scenario: an attacker finds a PDF file on a banking
Web site. The attacker creates a hostile Web site that links to the bank's PDF
user's computer once the link is clicked.
"PDF is trusted and tried and true -- everyone uses it," Dunham said.
"But instead of just viewing the file, you've initiated script that shouldn't
be executed. All you have to do is click on the PDF and the ball starts rolling."
Representatives from Adobe did not return a call from The Associated Press
on Wednesday night.
The flaw appears to target Microsoft Corp.'s Internet Explorer 6.0 Web browser
and earlier versions, and Mozilla's Firefox browser, the researchers said.
They recommended that users protect themselves by upgrading Internet Explorer
or changing Firefox's user options so the browser does not use the Acrobat plug-in.
Researchers said it's unclear how pervasive or harmful any future attacks might
"Given that it is easy to exploit, I would expect that we will see this
method used considerably in the coming days and weeks, until it is resolved,"
a Symantec researcher said in a posting on a company Web log.