The ApiThread function in the firewall service (aka TmPfw.exe) in Trend Micro Network Security Component (NSC) modules, as used in Trend Micro OfficeScan 8.0 SP1 Patch 1 and Internet Security 2007 and 2008 17.0.1224, allows remote attackers to cause a denial of service (service crash) via a packet with a large value in an unspecified size field.