US-CERT Technical Cyber Security Alert TA04-217A -- Multiple Vulnerabilities in libpng

2004-08-0500:00:00

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Multiple Vulnerabilities in libpng

Original release date: August 4, 2004
Last revised: –
Source: US-CERT

Systems Affected

Applications and systems that use the libpng library.

Overview

Several vulnerabilities exist in the libpng library, the most serious
of which could allow a remote attacker to execute arbitrary code on an
affected system.

I. Description

The Portable Network Graphics (PNG) image format is used as an
alternative to other image formats such as the Graphics Interchange
Format (GIF). The libpng is a popular reference library available for
application developers to support the PNG image format.

Several vulnerabilities have been reported in the libpng library. Any
application or system that uses this library may be affected. More
detailed information is available in the individual vulnerability
notes:

VU#388984 - libpng fails to properly check length of transparency
chunk (tRNS) data

A buffer overflow vulnerability has been discovered in the way that
libpng processes PNG images. This vulnerability could allow a remote
attacker to execute arbitrary code on a vulnerable system by
introducing a specially crafted PNG image.
(Other references: CAN-2004-0597)

VU#236656 - libpng png_handle_iCCP() NULL pointer dereference

Under some circumstances, a null pointer may be dereferenced during a
memory allocation in the png_handle_iCCP() function. As a result, a
PNG image with particular characteristics could cause the affected
application to crash. Similar errors are reported to exist in other
locations within libpng.
(Other references: CAN-2004-0598)

VU#160448 - libpng integer overflow in image height processing

An integer overflow error exists in the handling of PNG image height
within the png_read_png() function. As a result, a PNG image with
excessive height may cause an integer overflow during a memory
allocation operation, which could cause the affected application to
crash.
(Other references: CAN-2004-0599)

VU#477512 - libpng png_handle_sPLT() integer overflow

A potential integer overflow error exists during a memory allocation
operation within the png_handle_sPLT() function. It is unclear what
practical impact this error might have on applications using libpng.
(Other references: CAN-2004-0599)

VU#817368 - libpng png_handle_sBIT() performs insufficient bounds
checking

A potentially insufficient bounds check exists within the
png_handle_sBIT() function. A similar error exists in the
png_handle_hIST() function. While the code that contains these errors
could potentially permit a buffer overflow to occur during a
subsequent png_crc_read() operation, it is unclear what practical
vulnerabilities it might present in applications using libpng.
(Other references: CAN-2004-0597)

VU#286464 - libpng contains integer overflows in progressive display
image reading

The libpng library provides the ability to display interlaced, or
progressive display, PNG images. A number of potential integer
overflow errors exist in libpng's handling of such progressive display
images. While the code that contains these errors introduces dangerous
conditions, it is unclear what practical vulnerabilities it might
present in applications using libpng.
(Other references: CAN-2004-0599)

II. Impact

In the case of VU#388984, an attacker with the ability to introduce a
malformed PNG image to a vulnerable application could cause the
application to crash or could potentially execute arbitrary code with
the privileges of the user running the affected application.

In the case of VU#236656 and VU#160448, an attacker with the ability
to introduce a malformed PNG image to a vulnerable application could
cause the application to crash.

The impacts of the other vulnerabilities described above are unclear.

A remote attacker could cause an application to crash or potentially
execute arbitrary code by convincing a victim user to visit a
malicious web site or view an email message containing a malformed
image.

III. Solution

Apply a patch or upgrade

Apply the appropriate patch or upgrade as specified by your vendor.
For vendor-specific responses, please see your vendor's web site or
the individual vulnerability notes.

For individuals who rely on the original source of libpng, these
issues have been resolved in libpng version 1.2.6rc1 (release
candidate 1).

Appendix A. References

 * Chris Evans Security Advisory 2004.1 -
   &lt;http://scary.beasts.org/security/CESA-2004-001.txt&gt;
 * libpng Homepage - &lt;http://libpng.sourceforge.net&gt;
 * Portable Network Graphics &#40;PNG&#41; Homepage -
   &lt;http://www.libpng.org/pub/png&gt;
 * US-CERT Vulnerability Note VU#388984 -
   &lt;http://www.kb.cert.org/vuls/id/388984&gt;
 * US-CERT Vulnerability Note VU#817368 -
   &lt;http://www.kb.cert.org/vuls/id/817368&gt;
 * US-CERT Vulnerability Note VU#286464 -
   &lt;http://www.kb.cert.org/vuls/id/286484&gt;
 * US-CERT Vulnerability Note VU#477512 -
   &lt;http://www.kb.cert.org/vuls/id/477512&gt;
 * US-CERT Vulnerability Note VU#160448 -
   &lt;http://www.kb.cert.org/vuls/id/160448&gt;
 * US-CERT Vulnerability Note VU#236656 -
   &lt;http://www.kb.cert.org/vuls/id/236656&gt;
 * CVE CAN-2004-0597 -
   &lt;http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0597&gt;
 * CVE CAN-2004-0598 -
   &lt;http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0598&gt;
 * CVE CAN-2004-0599 -
   &lt;http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0599&gt;
 _________________________________________________________________

US-CERT thanks Chris Evans for researching and reporting these
vulnerabilities.
_________________________________________________________________

Feedback can be directed to the US-CERT Technical Staff.
_________________________________________________________________

The latest copy of this document can be found at:

<http://www.us-cert.gov/cas/techalerts/TA04-217A.html>

Revision History

Aug 4, 2004: Initial release

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