Downvote. The analysis in {08} is flawed, the claim "it gets drastically harder with each subsequent byte" is incorrect. This two-value canary is just as susceptible to a fork() attack as a usual one-value canary. More precisely: The number of tries an attacker needs to find the stack canary values is only increased linearly by this technique. With a one-value canary of 8 bytes, an attacker needs 8*256 fork() tries. With two canary values of 8 bytes each, the attacker needs 16*256 fork() attacks. But what we want is an exponential increase.