Remote users report that they are unable to log in to the VPN. The help desk confirms that each employee has a stable internet connection and correct permissions for VPN use but also identifies similar login errors for all affected users. Which of the following types of attacks most likely occurred?

Collision attacks involve attempting to find two different inputs that hash to the same output, primarily targeting cryptographic functions. This type of attack does not directly affect VPN logins or network accessibility. Since the problem is widespread among users rather than isolated to specific credentials, a collision attack is not a plausible explanation.

Credential spraying is a method where an attacker tries a small number of common passwords across many accounts, aiming to find valid credentials. While this could lead to login failures for individual users, the uniformity of the login errors across all affected users suggests a systemic issue rather than individual credential attempts. Hence, spraying does not adequately explain the situation.

On-path attacks involve intercepting communications between two parties, potentially compromising data or credentials. However, these attacks would not typically result in widespread login failures for all users simultaneously. The consistent error messages indicate a larger network issue rather than targeted interception of individual sessions.