NGSSoftware Insight Security Research Advisory

Name: Adobe Acrobat Reader XML Forms Data Format Buffer Overflow
Systems Affected: Adobe Acrobat Reader version 5.1
Severity: High Risk
Vendor URL:
Author: David Litchfield [ ]
Date Vendor Notified: 7th February 2004
Date of Public Advisory: 3rd March 2004
Advisory number: #NISR03022004
Advisory URL:

Adobe Acrobat Reader is a viewer that renders PDF documents. The Reader can
be extended using the XML Forms Data Format or XFDF. XFDF is a format for
representing forms data and annotations in a PDF document. XFDF files have a
.xfdf extention and are rendered automatically on downloaded when using
applications such as Internet Explorer. Also note that, regardless of the
file extention if the MIME type is set to "application/vnd.adobe.xfdf" the
file will be treated as a XFDF. When parsing an XFDF document the Adobe
Reader suffers from a classic stack based buffer overflow vulnerability.

When the xfdf file is parsed an unsafe call to sprintf is made in
preparation for outputting a debug message using OutputDebugString. Whether
the process is being debugged or not the vulnerable code is still called.
Rendering the file will trigger the overflow. A user would need to be enticed
to a web site that hosted a malicious xfdf file or sent one via e-mail.

Fix Information
On contacting Adobe, they confirmed that the current version is no longer
vulnerable and NGSSoftware urgently advises users of Adobe Reader to

About NGSSoftware
NGSSoftware design, research and develop intelligent, advanced application
security assessment scanners. Based in the United Kingdom, NGSSoftware have
offices in the South of London and the East Coast of Scotland. NGSSoftware's
sister company NGSConsulting, offers best of breed security consulting
services, specialising in application, host and network security
Source :

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