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OpenSSL Multiple Security Vulnerabilities
31 July 2002
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OpenSSL Security Advisory [30 July 2002]

This advisory consists of two independent advisories, merged, and is an official OpenSSL advisory.

Advisory 1

A.L. Digital Ltd and The Bunker (http://www.thebunker.net/) are conducting a security review of OpenSSL, under the DARPA program CHATS.


All four of these are potentially remotely exploitable.

1. The client master key in SSL2 could be oversized and overrun a buffer. This vulnerability was also independently discovered by consultants at Neohapsis (http://www.neohapsis.com/) who have also demonstrated that the vulerability is exploitable. Exploit code is NOT available at this time.

2. The session ID supplied to a client in SSL3 could be oversized and overrun a buffer.

3. The master key supplied to an SSL3 server could be oversized and overrun a stack-based buffer. This issues only affects OpenSSL 0.9.7 before 0.9.7-beta3 with Kerberos enabled.

4. Various buffers for ASCII representations of integers were too small on 64 bit platforms.

The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2002-0656 to issues 1-2, CAN-2002-0657 to issue 3, and CAN-2002-0655 to issue 4.

In addition various potential buffer overflows not known to be exploitable have had assertions added to defend against them.

Who is affected?

Everyone using OpenSSL 0.9.6d or earlier, or 0.9.7-beta2 or earlier or current development snapshots of 0.9.7 to provide SSL or TLS is vulnerable, whether client or server. 0.9.6d servers on 32-bit systems with SSL 2.0 disabled are not vulnerable.

SSLeay is probably also affected.


Apply the attached patch to OpenSSL 0.9.6d, or upgrade to OpenSSL 0.9.6e. Recompile all applications using OpenSSL to provide SSL or TLS.

A patch for 0.9.7 is available from the OpenSSL website (http://www.openssl.org/).

Servers can disable SSL2, alternatively disable all applications using SSL or TLS until the patches are applied. Users of 0.9.7 pre-release versions with Kerberos enabled will also have to disable Kerberos.

Client should be disabled altogether until the patches are applied.

Known Exploits

There are no know exploits available for these vulnerabilities. As noted above, Neohapsis have demonstrated internally that an exploit is possible, but have not released the exploit code.




The project leading to this advisory is sponsored by the Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory, Air Force Materiel Command, USAF, under agreement number F30602-01-2-0537.
The patch and advisory were prepared by Ben Laurie.

Advisory 2


The ASN1 parser can be confused by supplying it with certain invalid encodings.

The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2002-0659 to this issue.

Who is affected?

Any OpenSSL program which uses the ASN1 library to parse untrusted data. This includes all SSL or TLS applications, those using S/MIME (PKCS#7) or certificate generation routines.


Apply the patch to OpenSSL, or upgrade to OpenSSL 0.9.6e. Recompile all applications using OpenSSL.

Users of 0.9.7 pre-release versions should apply the patch or upgrade to 0.9.7-beta3 or later. Recompile all applications using OpenSSL.

There are no known exploits for this vulnerability.




This vulnerability was discovered by Adi Stav <stav@mercury.co.il> and James Yonan <jim@ntlp.com> independently. The patch is partly based on a version by Adi Stav.

The patch and advisory were prepared by Dr. Stephen Henson.

http://www.apache-ssl.org/ben.html http://www.thebunker.net/
Available for contract work.
"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff

Combined patches for OpenSSL 0.9.6d:

Combined patches for OpenSSL 0.9.7 beta 2:

URL for this Security Advisory:


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