Man-in-the-Middle TLS Protocol Downgrade Attack

arp cache diagram

A flaw was recently found in OpenSSL that allowed for an attacker to negotiate a lower version of TLS between the client and server (CVE-2014-3511). While this vulnerability was quickly patched, an attacker that has control of your traffic can still simulate this attack today. Let’s explore how this is possible through looking at man-in-the-middle attacks and how browsers handle SSL/TLS connections. In addition, we will see the implications of the attack on cryptographic security.