Who is affected?
=================

Everyone using OpenSSL releases prior to 0.9.8j as an SSL/TLS client
when connecting to a server whose certificate contains a DSA or ECDSA key.

Use of OpenSSL as an SSL/TLS client when connecting to a server whose
certificate uses an RSA key is NOT affected.

Verification of client certificates by OpenSSL servers for any key type
is NOT affected.

Recommendations for users of OpenSSL
=====================================

Users of OpenSSL 0.9.8 should update to the OpenSSL 0.9.8j release
which contains a patch to correct this issue.

The patch used is also appended to this advisory for users or
distributions who wish to backport this patch to versions they build
from source.

Recommendations for projects using OpenSSL
===========================================

Projects and products using OpenSSL should audit any use of the
routine EVP_VerifyFinal() to ensure that the return code is being
correctly handled.  As documented, this function returns 1 for a
successful verification, 0 for failure, and -1 for an error.

General recommendations
========================

Any server that has clients using OpenSSL verifying DSA or ECDSA
certificates, regardless of the software used by the server, should
either ensure that all clients are upgraded or stop using DSA/ECDSA
certificates. Note that unless certificates are revoked (and clients
check for revocation) impersonation will still be possible until the
certificate expires.

• "Do not use the MD5 algorithm"
  "Software developers, Certification Authorities, website owners, and users should avoid using the MD5 algorithm in any capacity. As previous research has demonstrated, it should be considered cryptographically broken and unsuitable for further use."
• "Scrutinize SSL certificates signed by certificates using the MD5 algorithm"
  "Users may wish to manually analyze the properties of web site certificates (...) Certificates listed as md5RSA or similar are affected. Such certificates that include strange or suspicious fields or other anomalies may be fraudulent. Because there are no reliable signs of tampering it must be noted that this workaround is error-prone and impractical for most users."