-----BEGIN PGP SIGNED MESSAGE----- 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: firstname.lastname@example.org Phone: +1 412-268-7090 (24-hour hotline) Fax: +1 412-268-6989 Postal address: CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 U.S.A. CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends. Using encryption We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from http://www.cert.org/CERT_PGP.key If you prefer to use DES, please call the CERT hotline for more information. Getting security information CERT publications and other security information are available from our web site http://www.cert.org/ To subscribe to the CERT mailing list for advisories and bulletins, send email to email@example.com. Please include in the body of your message subscribe cert-advisory * "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office. ______________________________________________________________________ NO WARRANTY Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement. _________________________________________________________________ Conditions for use, disclaimers, and sponsorship information Copyright 2002 Carnegie Mellon University. Revision History July 30, 2002: Initial release -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.8 iQCVAwUBPUa3CaCVPMXQI2HJAQFfMQP+OScRIgv9wK92OnJ+2GMwSbizihkdlczk UN8NMKOw7ZB5xF6U4juvac2lYFySvAw6O0h7AkUKIubmJINtxNP+8M174S9WluDF Y2Z1BNTcIaDuM6TculYk0+abX/Z1zPt/odAj5wtq0FHAG8JlwwYMuC+iOZPUG2be pqVKVFiWAVE= =w3ZJ -----END PGP SIGNATURE-----
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