What would you call an attack where an attacker can influence the state of the resource between check and
use?
This attack can happen with shared resources such as files, memory, or even variables in multithreaded
programs. This can cause the software to perform invalid actions when the resource is in an unexpected state.
The steps followed by this attack are usually the following: the software checks the state of a resource before
using that resource, but the resource’s state can change between the check and the use in a way that
invalidates the results of the check.

A.
TOCTOU attack

B.
Input checking attack

C.
Time of Check attack

D.
Time of Use attack

Explanation:
Time of check, time of use (TOCTOU) attacks are also called race conditions. An attacker attempts to alter a
condition after it has been checked by the operating system, but before it is used. TOCTOU is an example of a
state attack, where the attacker capitalizes on a change in operating system state.
Incorrect Answers:
B: Buffer overflow, directory traversal, cross-site scripting and SQL injection are just a few of the attacks that
can result from improper data validation. They can be said to be input checking attacks.
C: Time of Check attack is only half-true. This attack is called Time of check, time of use (TOCTOU) attack.
D: Time of Use attack is only half-true. This attack is called Time of check, time of use (TOCTOU) attack.

Conrad, Eric, Seth Misenar and Joshua Feldman, CISSP Study Guide, 2nd Edition, Syngress, Waltham, 2012,
p. 280