Is gcc's stack canary cryptographically secured? Does stack canary in general has to be cryptographically secured?

Huỳnh Thái Dương

10/19/23, 1:56 AM

I want to ask 2 questions:

Is GCC's stack canary cryptographically secured?
Does stack canary in general has to be cryptographically secured?

1 + 1

implementation

pseudo-random-generator

kelalaka

10/19/23, 7:38 AM

Stack canary is about the protection of the programs from overlflow. While programming cryptography one may benefit this, this is not about fundamentals of cryptography, it is about software implementation of cryptography. I would not rather rely on a generic compiler to do a security related protection. In general, those are heavy crafted. It would be a matter of time some security researchers might exploit this kind of tricks or they cannot or they did not notice. Defcon has lots of examples.

Score:2

Crypto

SAI Peregrinus

10/19/23, 3:39 AM

No. The stack canary has nothing to do with cryptography.

If you overrun the stack frame, your program has exhibited Undefined Behavior and all future execution is indeterminate. If you're lucky only the stack canary got overwritten, and the stack protector will still work when the function returns. In that case, your program will crash instead of continuing to execute indeterminate instructions. This cannot be relied upon, since a larger overrun could overwrite the return address and skip the stack protector code entirely.

+ 0

Elon Musk

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EN: Is gcc's stack canary cryptographically secured? Does stack canary in general has to be cryptographically secured?

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