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AUSCERT External Security Bulletin Redistribution
ESB-2007.0132 -- [Win][UNIX/Linux]
Server and client software using NSS SSL libraries
vulnerable to remote compromise
26 February 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: NSS libraries 3.11.4 and prior
Publisher: iDefense
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact: Execute Arbitrary Code/Commands
Access: Remote/Unauthenticated
CVE Names: CVE-2007-0009 CVE-2007-0008
Original Bulletin:
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=483
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=482
Comment: This bulletin contains two separate iDefense advisories for
buffer overflow vulnerabilities in both server and client SSLv2
implementations in the NSS (Network Security Services) library.
Note that this library is used to provide SSL capabilities in
several third party software products including Sun ONE Application
Server and Sun Java System Web Server.
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Mozilla Network Security Services SSLv2 Server Stack Overflow Vulnerability
iDefense Security Advisory 02.23.07
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 23, 2007
I. BACKGROUND
Network Security Services (NSS) is a set of libraries designed to support
cross-platform development of security-enabled client and server
applications, providing support for, among others, SSL (Secure Socket
Layer) protocol version 2 and 3. For more information visit the following
URL.
http://www.mozilla.org/projects/security/pki/nss/tools/
II. DESCRIPTION
Remote exploitation of an input validation error causing an integer
underflow in version 3.10 of the Mozilla Foundation's Network Security
Services (NSS) may allow an attacker to cause a stack-based buffer
overflow and execute arbitrary code on the affected application.
The vulnerability specifically exists in code responsible for handling the
client master key. While negotiating an SSLv2 session, a client can specify
invalid parameters which causes an integer underflow. The resulting value
is used as the amount of memory to copy into a fixed size stack buffer. As
a result, a potentially exploitable stack-based buffer overflow condition
occurs.
III. ANALYSIS
Successful exploitation of this vulnerability would allow an attacker to
execute arbitrary code in the context of the affected server. No
authentication is required to reach the vulnerable code. No user
interaction is required.
Since this vulnerability is in library code used by multiple applications,
the details of how an attacker would exploit it vary. In all cases, an
attacker would need to specify invalid parameters as part of the SSLv2
handshake.
Code execution has been demonstrated to be possible under Windows 2000
with a server utilizing the affected library. Depending on the precise
details of the server, this vulnerability may also be exploitable on other
platforms.
IV. DETECTION
iDefense has confirmed this vulnerability exists in versions 3.10 and
3.11.3 of the Mozilla Network Security Services. These libraries are used
in a variety of products from multiple vendors including Sun Microsystems,
Red Hat and Mozilla. Previous versions are also likely to be affected. The
names 'libnss3.so' on Linux based systems or 'nss3.dll' on Windows based
systems may indicate the library is being used by an application.
V. WORKAROUND
iDefense is not aware of any effective workaround for this vulnerability.
With some servers it may be possible to prevent exposure by disabling
SSLv2 support and employing a different protocol. However, this workaround
may prevent some clients from being able to access the server.
VI. VENDOR RESPONSE
The Mozilla Foundation has addressed this vulnerability in Mozilla
Foundation Security Advisory 2007-06. For more information, view their
advisory at the following URL.
http://www.mozilla.org/security/announce/2007/mfsa2007-06.html
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-0009 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
12/18/2006 Initial vendor notification
12/19/2006 Initial vendor response
02/23/2007 Coordinated public disclosure
IX. CREDIT
This vulnerability was reported to iDefense by regenrecht.
Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php
Free tools, research and upcoming events
http://labs.idefense.com/
X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
Permission is granted for the redistribution of this alert electronically.
It may not be edited in any way without the express written consent of
iDefense. If you wish to reprint the whole or any part of this alert in
any other medium other than electronically, please e-mail
customerservice@idefense.com for permission.
Disclaimer: The information in the advisory is believed to be accurate at
the time of publishing based on currently available information. Use of
the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on, this
information.
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Mozilla Network Security Services SSLv2 Client Integer Underflow
Vulnerability
iDefense Security Advisory 02.23.07
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 23, 2007
I. BACKGROUND
Network Security Services (NSS) is a set of libraries designed to support
cross-platform development of security-enabled client and server
applications, providing support for, among others, SSL (Secure Socket
Layer) protocol version 2 and 3. For more information visit the following
URL.
http://www.mozilla.org/projects/security/pki/nss/tools/
II. DESCRIPTION
Remote exploitation of an input validation error causing an integer
underflow in version 3.10 of the Mozilla Foundation's Network Security
Services (NSS) may allow an attacker to execute arbitrary code in the
context of the affected application.
The vulnerability specifically exists due to a design error in the
processing of malformed SSLv2 server messages. By sending a certificate
with a public key too small to encrypt the "Master Secret", heap
corruption can be triggered which may result in the execution of arbitrary
code.
III. ANALYSIS
Successful exploitation of this vulnerability would allow an attacker to
execute arbitrary code in the context of the user running the affected
client.
Since this vulnerability is in library code used by multiple applications,
the details of how an attacker would exploit it vary. In all cases, the
affected client connects to a server which replies in the initial
handshake with a specially crafted certificate. This causes a heap based
overflow with random data and eventually causes a fault writing past the
end of the allocated space. Some applications may use values from the
overwritten memory locations before the program exits. In this case, it
may be possible for an attacker to cause code to execute.
Although the data which overruns the heap is random, code execution is
possible on some platforms with some applications using the library.
Although unreliable, iDefense has demonstrated that this vulnerability can
result in code execution with Firefox 1.5.0.9 on Windows XP.
IV. DETECTION
iDefense has confirmed this vulnerability exists in versions 3.10 and
3.11.3 of Mozilla Network Security Services. These libraries are used in a
variety of products from multiple vendors including Sun Microsystems, Red
Hat and Mozilla. Previous versions are also likely to be affected. The
names 'libnss3.so' on Linux based systems or 'nss3.dll' on Windows based
systems may indicate the library is being used by an application.
V. WORKAROUND
iDefense is not aware of any effective workaround for this vulnerability.
With some clients, it may be possible to mitigate exposure by disabling
SSLv2 support. However, this may cause problems connecting to servers
using only SSLv2.
VI. VENDOR RESPONSE
The Mozilla Foundation has addressed this vulnerability in Mozilla
Foundation Security Advisory 2007-06. For more information, view their
advisory at the following URL.
http://www.mozilla.org/security/announce/2007/mfsa2007-06.html
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-0008 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
12/18/2006 Initial vendor notification
12/19/2006 Initial vendor response
02/23/2007 Coordinated public disclosure
IX. CREDIT
This vulnerability was reported to iDefense by regenrecht.
Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php
Free tools, research and upcoming events
http://labs.idefense.com/
X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
Permission is granted for the redistribution of this alert electronically.
It may not be edited in any way without the express written consent of
iDefense. If you wish to reprint the whole or any part of this alert in
any other medium other than electronically, please e-mail
customerservice@idefense.com for permission.
Disclaimer: The information in the advisory is believed to be accurate at
the time of publishing based on currently available information. Use of
the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on, this
information.
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The University of Queensland
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