avast! Antivirus 4.6.763 and earlier sets "BUILTIN\Everyone" permissions to critical system files in the installation folder, which allows local users to gain privileges or disable protection by modifying those files.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25336
http://www.vupen.com/english/advisories/2006/1011
http://www.securityfocus.com/bid/17158
http://www.dslreports.com/forum/remark%2C15601404~days=9999~start=20