Which measure does NOT protect against broken authentication for a web application?

The measure that does not protect against broken authentication for a web application is the implementation of Address Space Layout Randomization (ASLR). ASLR is a security technique primarily aimed at protecting against certain types of memory corruption vulnerabilities, such as buffer overflow attacks. It works by randomizing the memory addresses used by system and application processes, making it more difficult for an attacker to predict target memory locations in order to execute malicious code.

While ASLR is a vital component of overall application security, it does not address the specific risks associated with broken authentication. Broken authentication vulnerabilities occur when an application fails to adequately verify the identity of users, which can lead to unauthorized access. The measures that do enhance authentication security include multifactor authentication, which adds layers to the verification process; password checks, which enforce strong password policies; and setting limits on login attempts to mitigate brute-force attacks.

Therefore, ASLR's role is more related to memory protection than authentication issues, making it the correct choice as the measure that does not directly protect against broken authentication vulnerabilities in a web application.