THC-SSL DOS was developed by a hacking group called The Hacker’s Choice (THC), as a proof-of-concept to encourage vendors to patch a serious SSL vulnerability. THC-SSL-DOS, as with other "
low and slow" attacks, requires only a small number of packets to cause denial-of-service for a fairly large server. It works by initiating a regular SSL handshake and then immediately requesting for the renegotiation of the encryption key, constantly repeating this server resource-intensive renegotiation request until all server resources have been exhausted.