David Brumley and Dan Boneh of Stanford University have researched and
documented a timing attack on OpenSSL which allows local and remote
attackers to extract the RSA private key of a server. The OpenSSL RSA
implementation is generally vulnerable to these type of attacks unless RSA
blinding has been turned on. See this
paper (pdf format) for additional details.
Typically, RSA blinding is not enabled by OpenSSL based applications,
mainly because it is not obvious how to do so when using OpenSSL to provide
SSL/TLS. This problem affects mostly all applications using OpenSSL and
have to be rebuilded against the fixed OpenSSL version (where RSA blinding
is now enabled by default) or have to enable RSA blinding explicitly their
own.
The performance impact of RSA blinding appears to be small (a few percent
only) and the RSA functionality is still fully compatible. The Common
Vulnerabilities and Exposures (CVE) project assigned the id
CAN-2003-0147 to the problem.
