Impact of TLS/SSL Renegotiation Vulnerability on HTTPS: Less Known Issues

abb — Sun, 12 Sep 2010 11:10:31 +0000

There is a couple of issues with TLS/SSL renegotiation vulnerability in the context of HTTPS protocol, which appear not to have made their way to the public.

1. Plain text prefix injection is not the only risk. The original advisory [1] mentions the possibility of "forwarding and repurposing of client certificate authentication credentials". In oss-sec maillist Marsh Ray goes in more details [2], and [3] dedicates one slide to "client certificate redirection".

2. The renegotiation vulnerability provides for an additional attack vector to exploit web application vulnerabilities. For example, MiTM attackers can use it to deliver an exploit for a non-persistent XSS bug to client's browser.

References:

[1] http://www.phonefactor.com/sslgapdocs/Renegotiating_TLS.pdf
[2] http://seclists.org/oss-sec/2009/q4/137
[3] http://www.troopers10.org/content/e728/e897/e903/TROOPERS10_History_of_…

abb Sun, 09/12/2010 - 13:10

Enabling SSL/TLS Renegotiation in Java

alla — Tue, 08 Jun 2010 12:40:29 +0000

Enabling SSL/TLS Renegotiation in Java

All the crazy SSL servers seem to come my way - ones that only support weird combinations of protocols and ciphers, ones that require client certificates stored on PKCS#11 hardware, and ones that require SSL renegotiation.

Turns out that Sun has recently disabled SSL/TLS renegotiation in Java by default as a workaround for SSL/TLS renegotiation vulnerability. This becomes a problem when trying to test an HTTPS server that actually requires renegotiation. Burp suite reacts to it with an error message saying "javax.net.ssl.SSLException: HelloRequest followed by an unexpected handshake message" or, if I enable only TLSv1, with a message saying "javax.net.ssl.SSLHandshakeException: renegotiation is not allowed". I expect that other Java-based proxies, such as WebScarab behave in a similar way.

Fortunately, renegotiation can be explicitly enabled by setting the Java system property system property sun.security.ssl.allowUnsafeRenegotiation to true. For example, to run Burp suite we can do :

java -Dsun.security.ssl.allowUnsafeRenegotiation=true -jar burpsuite_pro_v1.3.04.jar

alla Tue, 06/08/2010 - 14:40

tls renegotiation

Impact of TLS/SSL Renegotiation Vulnerability on HTTPS: Less Known Issues

Enabling SSL/TLS Renegotiation in Java