Researchers have discovered a timing attack on RSA keys, to which
OpenSSL is generally vulnerable, unless RSA blinding has been turned
on.
Typically, it will not have been, because it is not easily possible to
do so when using OpenSSL to provide SSL or TLS.
The enclosed patch switches blinding on by default. Applications that
wish to can remove the blinding with RSA_blinding_off(), but this is
not generally advised. It is also possible to disable it completely by
defining OPENSSL_NO_FORCE_RSA_BLINDING at compile-time.
The performance impact of blinding appears to be small (a few
percent).
This problem affects many applications using OpenSSL, in particular,
almost all SSL-enabled Apaches. You should rebuild and reinstall
OpenSSL, and all affected applications.
The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the name CAN-2003-0147 to this issue.
* Add patch from http://www.openssl.org/news/secadv_20030319.txt:
Czech cryptologists Vlastimil Klima, Ondrej Pokorny, and Tomas Rosa
have come up with an extension of the "Bleichenbacher attack" on RSA
with PKCS #1 v1.5 padding as used in SSL 3.0 and TLS 1.0. Their
attack requires the attacker to open millions of SSL/TLS connections
to the server under attack; the server's behaviour when faced with
specially made-up RSA ciphertexts can reveal information that in
effect allows the attacker to perform a single RSA private key
operation on a ciphertext of its choice using the server's RSA key.
Note that the server's RSA key is not compromised in this attack.
* Bump PKGREVISION.
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