Finding SSL/TLS Master Secrets with PANDA
mercredi 2 octobre 2013 à 10:35 CAFAI, le 02/10/2013 à 10:35
Monitoring SSL/TLS-encrypted traffic is a classic problem for intrusion detection systems. Currently, hypervisor- or network- based IDSes that wish to analyze encrypted traffic must perform a man-in-the-middle attack on the connection, presenting a false server certificate to the client. Not only does this require the client to cooperate by trusting certificates signed by the intrusion detection system, it also takes control of the certificate verification process out of the hands of the client---a dangerous step, given that many existing SSL/TLS interception proxies have a history of certificate trust vulnerabilities.
Instead of a man-in-the-middle attack, we can instead attempt to locate the code that generates SSL/TLS master secret; this secret is sufficient to decrypt any encrypted traffic in a given session, giving us a "man-on-the-inside". Once we have identified the location of the code that generates this secret, we can hook it using any number of standard techniques in order to dump out the master secret. This secret can then be provided to an IDS to decrypt the content of the SSL stream; it may also be provided to a tool like Wireshark to decrypt packet captures after the fact (even if perfect forward secrecy is used).
In this tutorial, we will show how to use a PANDA plugin called keyfind, which examines memory accesses made during a recorded session and looks for code that processes SSL/TLS master secrets.
(Permalink)
Monitoring SSL/TLS-encrypted traffic is a classic problem for intrusion detection systems. Currently, hypervisor- or network- based IDSes that wish to analyze encrypted traffic must perform a man-in-the-middle attack on the connection, presenting a false server certificate to the client. Not only does this require the client to cooperate by trusting certificates signed by the intrusion detection system, it also takes control of the certificate verification process out of the hands of the client---a dangerous step, given that many existing SSL/TLS interception proxies have a history of certificate trust vulnerabilities.
Instead of a man-in-the-middle attack, we can instead attempt to locate the code that generates SSL/TLS master secret; this secret is sufficient to decrypt any encrypted traffic in a given session, giving us a "man-on-the-inside". Once we have identified the location of the code that generates this secret, we can hook it using any number of standard techniques in order to dump out the master secret. This secret can then be provided to an IDS to decrypt the content of the SSL stream; it may also be provided to a tool like Wireshark to decrypt packet captures after the fact (even if perfect forward secrecy is used).
In this tutorial, we will show how to use a PANDA plugin called keyfind, which examines memory accesses made during a recorded session and looks for code that processes SSL/TLS master secrets.
(Permalink)