CERT Advisory CA-2002-23 Multiple Vulnerabilities In OpenSSL

From: CERT Advisory (cert-advisory@cert.org)
Date: 07/30/02 

Date: Tue, 30 Jul 2002 12:37:49 -0400
From: CERT Advisory <cert-advisory@cert.org>
To: cert-advisory@cert.org

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CERT Advisory CA-2002-23 Multiple Vulnerabilities In OpenSSL

   Original release date: July 30, 2002
   Last revised: --
   Source: CERT/CC

   A complete revision history can be found at the end of this file.

Systems Affected

     * OpenSSL prior to 0.9.6e, up to and including pre-release
       0.9.7-beta2
     * OpenSSL pre-release 0.9.7-beta2 and prior with Kerberos enabled
     * SSLeay library

Overview

   There are four remotely exploitable buffer overflows in OpenSSL. There
   are also encoding problems in the ASN.1 library used by OpenSSL.
   Several of these vulnerabilities could be used by a remote attacker to
   execute arbitrary code on the target system. All could be used to
   create denial of service.

I. Description

   OpenSSL is a widely deployed, open source implementation of the Secure
   Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1)
   protocols as well as a full-strength general purpose cryptography
   library. The SSL and TLS protocols are used to provide a secure
   connection between a client and a server for higher level protocols
   such as HTTP. Four remotely exploitable vulnerabilities exist in many
   OpenSSL client and server systems.

   VU#102795 - OpenSSL servers contain a buffer overflow during the SSLv2
   handshake process

     Versions of OpenSSL servers prior to 0.9.6e and pre-release version
     0.9.7-beta2 contain a remotely exploitable buffer overflow
     vulnerability. This vulnerability can be exploited by a client
     using a malformed key during the handshake process with an SSL
     server connection. Note that only SSLv2-supported sessions are
     affected by this issue.

     This issue is also being referenced as CAN-2002-0656.

   VU#258555 - OpenSSL clients contain a buffer overflow during the SSLv3
   handshake process

     OpenSSL clients using SSLv3 prior to version 0.9.6e and pre-release
     version 0.9.7-beta2 contain a buffer overflow vulnerability. A
     malicious server can exploit this by sending a large session ID to
     the client during the handshake process.

     This issue is also being referenced as CAN-2002-0656.

   VU#561275 - OpenSSL servers with Kerberos enabled contain a remotely
   exploitable buffer overflow vulnerability during the SSLv3 handshake
   process

     Servers running OpenSSL pre-release version 0.9.7 with Kerberos
     enabled contain a remotely exploitable buffer overflow
     vulnerability. This vulnerability can be exploited by a malicious
     client sending a malformed key during the SSLv3 handshake process
     with the server.

     This issue is also being referenced as CAN-2002-0657.

   VU#308891 - OpenSSL contains multiple buffers overflows in buffers
   that are used to hold ASCII representations of integers

     OpenSSL clients and servers prior to version 0.9.6e and pre-release
     version 0.9.7-beta2 contain multiple remotely exploitable buffer
     overflow vulnerabilities if running on 64-bit platforms. These
     buffers are used to hold ASCII representations of integers.

     This issue is also being referenced as CAN-2002-0655.

   In addition, a separate issue has been identified in OpenSSL involving
   malformed ASN.1 encodings. Affected components include SSL or TLS
   applications, as well as S/MIME, PKCS#7, and certificate creation
   routines.

   VU#748355 - ASN.1 encoding errors exist in implementations of SSL,
   TLS, S/MIME, PKCS#7 routines

     The ASN.1 library used by OpenSSL has various encoding errors that
     allow malformed certificate encodings to be parsed incorrectly.
     Exploitation of this vulnerability can lead to remote
     denial-of-service issues. Routines affected include those
     supporting SSL and TLS applications, as well as those supporting
     S/MIME, PKCS#7, and certificate creation.

     This issue is also being referenced as CAN-2002-0659.

   Although these vulnerabilities affect OpenSSL, other implementations
   of the SSL protocol that use or share a common code base may be
   affected. This includes implementations that are derived from the
   SSLeay library developed by Eric A. Young and Tim J. Hudson.

   As noted in the OpenSSL advisory as well, sites running OpenSSL 0.9.6d
   servers on 32-bit platforms with SSLv2 handshaking disabled will not
   be affected by any of the buffer overflows described above. However,
   due to the nature of the ASN.1 encoding errors, such sites may still
   be affected by denial-of-service situations.

II. Impact

   By exploiting the buffer overflows above, a remote attacker can
   execute arbitrary code on a vulnerable server or client system or
   cause a denial-of-service situation. Exploitation of the ASN.1
   encoding errors can lead to a denial of service.

III. Solution

Apply a patch from your vendor

   Appendix A contains information provided by vendors for this advisory.
   As vendors report new information to the CERT/CC, we will update this
   section and note the changes in our revision history. If a particular
   vendor is not listed below or in the individual vulnerability notes,
   we have not received their comments. Please contact your vendor
   directly.

Upgrade to version 0.9.6e of OpenSSL

   Upgrade to version 0.9.6e of OpenSSL to resolve the issues addressed
   in this advisory. As noted in the OpenSSL advisory, separate patches
   are available:

     Combined patches for OpenSSL 0.9.6d:
     http://www.openssl.org/news/patch_20020730_0_9_6d.txt

   After either applying the patches above or upgrading to 0.9.6e,
   recompile all applications using OpenSSL to support SSL or TLS
   services, and restart said services or systems. This will eliminate
   all known vulnerable code.

   Sites running OpenSSL pre-release version 0.9.7-beta2 may wish to
   upgrade to 0.9.7-beta3, which corrects these vulnerabilities. Separate
   patches are available as well:

     Combined patches for OpenSSL 0.9.7 beta 2:
     http://www.openssl.org/news/patch_20020730_0_9_7.txt

Disable vulnerable applications or services

   Until fixes for these vulnerabilities can be applied, disable all
   applications that use vulnerable implementations of OpenSSL. Systems
   with OpenSSL 0.9.7 pre-release with Kerberos enabled also need to
   disable Kerberos to protect against VU#561275. As a best practice, the
   CERT/CC recommends disabling all services that are not explicitly
   required. Before deciding to disable SSL or TLS, carefully consider
   the impact that this will have on your service requirements.

   Disabling SSLv2 handshaking will prevent exploitation of VU#102795.
   However, due to the nature of the ASN.1 encoding errors, such sites
   would still be vulnerable to denial-of-service attacks.

Appendix A. - Vendor Information

   This appendix contains information provided by vendors for this
   advisory. As vendors report new information to the CERT/CC, we will
   update this section and note the changes in our revision history. If a
   particular vendor is not listed below or in the individual
   vulnerability notes, we have not received their comments.

OpenLDAP

     The OpenLDAP Project uses OpenSSL. Rebuilding OpenLDAP with updated
     versions of OpenSSL should adequately address reported issues.
     Those using packaged versions of OpenLDAP should contact the
     package distributor for update information.

OpenSSL

     Please see http://www.openssl.org/news/secadv_20020730.txt.

Red Hat

     Red Hat distributes affected versions of OpenSSL in all Red Hat
     Linux distributions as well as the Stronghold web server. Red Hat
     Linux errata packages that fix the above vulnerabilities
     (CAN-2002-0655 and CAN-2002-0656) are available from the URL below.
     Users of the Red Hat Network are able to update their systems using
     the 'up2date' tool. A future update will fix the potential remote
     DOS in the ASN.1 encoding (CAN-2002-0659)

     http://rhn.redhat.com/errata/RHSA-2002-155.html
     _________________________________________________________________

   These vulnerabilities were discovered and reported by the following:
     * VU#102795 - discovered by A.L. Digital Ltd and independently
       discovered and reported by John McDonald of Neohapsis
     * VU#258555, VU#561275, VU#308891 - discovered by A.L. Digital Ltd
     * VU#748355 - discovered by Adi Stav and James Yonan independently

   The CERT/CC thanks the OpenSSL team for the work they put into their
   advisory, on which this document is largely based.
     _________________________________________________________________

   Feedback can be directed to the authors: Jason A. Rafail, Cory F.
   Cohen, Jeffrey S. Havrilla, Shawn V. Hernan.
   ______________________________________________________________________

   This document is available from:
   http://www.cert.org/advisories/CA-2002-23.html
   ______________________________________________________________________

CERT/CC Contact Information

   Email: cert@cert.org
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   Revision History
July 30, 2002: Initial release

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