An unauthorized user attempting to access confidential files can be detected through application logs by the presence of multiple failed login attempts followed by a successful login, especially if the timestamps of these events suggest that they occurred in rapid succession. This could imply a brute force attack or the compromise of legitimate credentials. It's essential to investigate such anomalies to prevent potential data breaches. Repeated timeouts suggest a denial of service condition but don't necessarily indicate unauthorized file access, while connection errors and single login failures are common and might not represent security incidents.