VSR Advisory: PDF Tools AG - PDF Form Filling and Flattening Tool Buffer Overflow



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Virtual Security Research, LLC.
http://www.vsecurity.com/
Security Advisory

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Advisory Name: PDF Form Filling and Flattening Tool Buffer Overflow
Release Date: 2006-05-23
Application: PDF Tools AG - PDF Form Filling and Flattening Tool
Version: 3.0 (Windows)
(other versions and platforms untested)
Severity: High
Author: George D. Gal <ggal_at_vsecurity.com>
Vendor Status: Vendor Notified, Fix Available
CVE Candidate: CVE-2006-2549
Reference:
http://www.vsecurity.com/bulletins/advisories/2006/pdf-form-filling.txt
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Product Description:

From the pdf-tools.com website[1]:

"PDF Tools AG is a world leader in PDF (The Adobe Portable Document Format)
programming technology, delivering reliable PDF products to international
customers in virtually all market segments."

"PDF Form Filling and Flattening Tool is a command line tool that can
create, edit, fill in and delete form fields in a PDF document."


Vulnerability Overview:

On April 18th, 2006 VSR has identified a stack overflow in the PDF Tools AG
PDF Form Filling and Flattening tool. Although this is a traditional
command line utility there may be a risk to those users of the application
who use it within web application or a network service, particularly when
relying on user supplied input to generate the PDF form field name or value
pairs.

In situations where user supplied input is used to populate a control file
of name value pairs without sufficient input validation the form field
names are susceptible to overflow. The buffer overflow occurs as a
direct result of unsafe string copy operations to a 256 byte fixed length
buffer. The binary is also susceptible to overflows of the PDF form field
names when specified on the command line instead of within a control file.

The following command may be used to check for the existence of the
vulnerability in the PDF form filling and flattening tool:

./pdformp.exe input.pdf output.pdf `perl -e 'print "A"x260;'`=foo

Vendor Response:

PDF Tools AG was first notified on 2006-04-19. The following time line
outlines the responses from the vendor regarding this issue:

2006-04-20 - Acknowledgment of security notification received from VSR.
Vendor stated that they only support registered customers
of the product.
2006-05-02 - Vendor response acknowledging overflow which will be
resolved in the next pre-release version.
2006-05-10 - Vendor response providing estimated release schedule.
2006-05-15 - Vendor response notifying VSR of publicly released fix.

Recommendation:

PDF Tools AG customers should upgrade to the latest build of the PDF
Form Filling and Flattening tool (build 3.1.0.12) released on
May 10th 2006.

The upgrade is available via:

http://www.pdf-tools.com/asp/products.asp?name=FF&type=shell

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Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues. These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

CVE-2006-2549

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References:

1. PDF Tools AG Form Filling and Flattening Tool
http://www.pdf-tools.com/asp/products.asp?name=FF&type=shell

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Vulnerability Disclosure Policy:

http://www.vsecurity.com/disclosurepolicy.html

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Copyright 2006 Virtual Security Research, LLC. All rights reserved.
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