Sophos Anti-Virus 7.0.5, and other 7.x versions, when Runtime Behavioural Analysis is enabled, allows local users to cause a denial of service (reboot with the product disabled) and possibly gain privileges via a zero value in a certain length field in the ObjectAttributes argument to the NtCreateKey hooked System Service Descriptor Table (SSDT) function.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42083
http://www.vupen.com/english/advisories/2008/1381
http://www.sophos.com/support/knowledgebase/article/37810.html
http://www.securityfocus.com/bid/28743
http://www.securityfocus.com/archive/1/491405/100/0/threaded
http://www.coresecurity.com/?action=item&id=2249
http://securitytracker.com/id?1019945