The Trend Micro AntiVirus scan engine before 8.550-1001, as used in Trend Micro PC-Cillin Internet Security 2007, and Tmxpflt.sys 8.320.1004 and 8.500.0.1002, has weak permissions (Everyone:Write) for the \\.\Tmfilter device, which allows local users to send arbitrary content to the device via the IOCTL functionality.  NOTE: this can be leveraged for privilege escalation by exploiting a buffer overflow in the handler for IOCTL 0xa0284403.