A security vulnerability in the TLS protocol (TLS 1.0 or later and SSLv3) may allow an unauthenticated, remote attacker to conduct man-in-the-middle (MITM) type of attacks where chosen plain text may be injected as a prefix in an user's TLS session. This vulnerability does not allow one to decrypt the intercepted network communication.

This issue is referenced in CVE-2009-3555

Exact nature of the impact depends on the application making use of the TLS facility. Applications which use Network Security Services (NSS), Java Secure Socket Extensions (JSSE), OpenSSL or GnuTLS libraries may be affected.

Sun is evaluating the impact of the issue on various products which make use of the TLS libraries. We are working to fix the TLS implementations according to the TLS protocol standard extensions currently being developed.

Solaris Kernel SSL proxy module KSSL does not support client renegotiation or rehandshake. It ignores the rehandshake message which is an allowed behavior by the SSL/TLS specification. Hence it is not vulnerable to this issue. KSSL (see ksslcfg(1M)) is available in Solaris 10 and OpenSolaris. It may be used to workaround the described issue.

Please refer to Sun Alert 273029 for more information related to how this issue affects OpenSSL libraries provided with Solaris and available workarounds.

tags: gnutls jsse nss openssl security tls vulnerability