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TUCoPS :: Web :: General :: n-159.txt

OpenSSL Security Vulnerability in ASN 1 parsing (CIAC N-159)





             __________________________________________________________

                       The U.S. Department of Energy
                   Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

           OpenSSL Security Vulnerabilities in ASN.1 parsing

September 30, 2003 19:00 GMT                                      Number N-159
[REVISED 1 Oct 2003]
[REVISED 2 Oct 2003]
______________________________________________________________________________
PROBLEM:       1) Certain ASN.1 encodings that are rejected as invalid by the 
               parser can trigger a bug in the deallocation of the 
               corresponding data structure, corrupting the stack. 
			   2) Unusual ASN.1 tag values can cause an out of bounds read
               under certain circumstances. 
			   3) A malformed public key in a certificate will crash the verify 
               code if it is not set to ignore public key decoding errors. 
			   4) An error in the SSL/TLS protocol handling, a server will parse 
               a client certificate when one is not specifically requested. 
PLATFORM:      All versions of OpenSSL up to and including 0.9.6j and 0.9.7b 
               and all versions of SSLeay 
               Cisco IOS 12.1(11)E & later in the 12.1E release train
               Cisco PIX Firewall
               Cisco Firewall Services Module (FWSM) for Cisco Catalyst 6500 
                  Series and 7600 Series routers
               Cisco Network Analysis Modules (NAM) for Cisco Catalyst 6000 and
                  6500 Series switches and Cisco 7600 Series routers
               Cisco Content Service Switch (CSS) 11000 series
               Cisco Global Site Selector (GSS) 4480
               Cisco Application & Content Networking Software (ACNS)
               Cisco SN 5428 Storage Router
               CiscoWorks 1105 Hosting Solution Engine (HSE)
               CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)
               CiscoWorks Common Services (CMF)
               Cisco SIP Proxy Server (SPS)
               HP-UX B.11.00, B.11.11, B.11.20, B.11.22, B.11.23
DAMAGE:        Denial of service 
SOLUTION:      Upgrade to OpenSSL 0.9.7c or 0.9.6k. Recompile any OpenSSL 
               applications statically linked to OpenSSL libraries. 
               Check with your vendor for platform-specific solutions.
______________________________________________________________________________
VULNERABILITY  The risk is LOW. This is a denial of service and it is 
ASSESSMENT:    currently unknown if the attacker can run arbitrary code. 
______________________________________________________________________________
LINKS: 
 CIAC BULLETIN:      http://www.ciac.org/ciac/bulletins/n-159.shtml 
 ORIGINAL BULLETIN:  http://www.openssl.org/news/secadv_20030930.txt 
 ADDITIONAL LINKS:   Cisco Security Advisory Document ID: 45643
                     http://www.cisco.com/warp/public/707/cisco-sa-20030930-ssl.
                      shtml
                     CERT Advisory CA-2003-26
                     http://www.cert.org/advisories/CA-2003-26.html
                     DHS/FedCIRC Advisory FA-2003-26
                     http://www2.fedcirc.gov/advisories/FA-2003-26.html
                     Visit Hewlett Packard Subscription Service for:
                     HPSBUX0310-284 (SSRT3622)                     
______________________________________________________________________________
REVISION HISTORY: 
10/1/03 - Added Cisco Security Advisory Cisco-SA-20030930 and updated PLATFORM 
          Section.
10/2/03 - Added links for CERT Advisory CA-2003-26, FedCIRC Advisory FA-2003-26,
          and Hewlett Packard HPSBUX0310-284 (SSRT3622).							

[****** START OpenSSL Security Advisory ******]

OpenSSL Security Advisory [30 September 2003]

Vulnerabilities in ASN.1 parsing
================================

NISCC (www.niscc.gov.uk) prepared a test suite to check the operation
of SSL/TLS software when presented with a wide range of malformed client
certificates.

Dr Stephen Henson (steve@openssl.org) of the OpenSSL core team
identified and prepared fixes for a number of vulnerabilities in the
OpenSSL ASN1 code when running the test suite.

A bug in OpenSSLs SSL/TLS protocol was also identified which causes
OpenSSL to parse a client certificate from an SSL/TLS client when it
should reject it as a protocol error.

Vulnerabilities
---------------

1. Certain ASN.1 encodings that are rejected as invalid by the parser
can trigger a bug in the deallocation of the corresponding data
structure, corrupting the stack. This can be used as a denial of service
attack. It is currently unknown whether this can be exploited to run
malicious code. This issue does not affect OpenSSL 0.9.6.

2. Unusual ASN.1 tag values can cause an out of bounds read under
certain circumstances, resulting in a denial of service vulnerability.

3. A malformed public key in a certificate will crash the verify code if
it is set to ignore public key decoding errors. Public key decode errors
are not normally ignored, except for debugging purposes, so this is
unlikely to affect production code. Exploitation of an affected
application would result in a denial of service vulnerability.

4. Due to an error in the SSL/TLS protocol handling, a server will parse
a client certificate when one is not specifically requested. This by
itself is not strictly speaking a vulnerability but it does mean that
*all* SSL/TLS servers that use OpenSSL can be attacked using
vulnerabilities 1, 2 and 3 even if they don't enable client authentication.

Who is affected?
----------------

All versions of OpenSSL up to and including 0.9.6j and 0.9.7b and all
versions of SSLeay are affected.

Any application that makes use of OpenSSL's ASN1 library to parse
untrusted data. This includes all SSL or TLS applications, those using
S/MIME (PKCS#7) or certificate generation routines.

Recommendations
---------------

Upgrade to OpenSSL 0.9.7c or 0.9.6k. Recompile any OpenSSL applications
statically linked to OpenSSL libraries.

References
----------

The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the name CAN-2003-0545 for issue 1:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0545

and CAN-2003-0543 and CAN-2003-0544 for issue 2:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0543
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0544

URL for this Security Advisory:
http://www.openssl.org/news/secadv_20030930.txt



[****** END OpenSSL Security Advisory  ******]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of OpenSSL for the 
information contained in this bulletin.
_______________________________________________________________________________


CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
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    FAX:      +1 925-423-8002
    STU-III:  +1 925-423-2604
    E-mail:   ciac@ciac.org

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

   World Wide Web:      http://www.ciac.org/
   Anonymous FTP:       ftp.ciac.org

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.

This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
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