This exploit, CVE-2014-6271, is based on the logic in NCC group's GitHub.

In GNU Bash (through 4.3), processes trailing strings after function definitions in the values of environment variables allow remote attackers to execute arbitrary code via a crafted environment. This is demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, AKA "ShellShock."