The HP Integrated Lights-Out (iLO) BMC implementation allows remote attackers to bypass authentication and execute arbitrary IPMI commands by using cipher suite 0 (aka cipher zero) and an arbitrary password.
fish2.com/ipmi/cipherzero.html
osvdb.org/show/osvdb/93040
www.metasploit.com/modules/auxiliary/scanner/ipmi/ipmi_cipher_zero
www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html
www.wired.com/threatlevel/2013/07/ipmi/
exchange.xforce.ibmcloud.com/vulnerabilities/85569
lists.gnu.org/archive/html/freeipmi-devel/2013-02/msg00013.html