The attack worked first by getting Bogner’s malicious file quarantined by the AV program running on the targeted computer. The pentester then exploited vulnerabilities in the AV programs that allowed unprivileged users to restore the quarantined files. He further abused a Windows feature known as NTFS file junction point to force the restore operation to put his malicious file into a privileged directory of Bogner’s choosing. The technique took advantage of another Windows feature known as Dynamic Link Library search order. With that, Bogner’s malware ran with full privileges.
Source: How AV can open you to attacks that otherwise wouldn’t be possible | Ars Technica