send/recv is the syscall side of the kernel, so no that's still local attackers. "I'm going to try to find bugs by calling 'recv' with strange parameters" will

send/recv is the syscall side of the kernel, so no that's still local attackers. "I'm going to try to find bugs by calling 'recv' with strange parameters" will not find bugs that are triggered by any type of data coming off of the wire. Yes, it's not impossible, but seems about as likely to me as fuzzing syscalls locally would be at finding security holes in www.facebook.com by connecting to it and fuzzing up an SSL connection.