A watering hole attack occurs when attackers compromise a website that is frequently visited by targeted users—in this case, the payment processing site used by employees. The compromised site then delivers malicious payloads to visitors, such as downloading malicious applications without user consent.

XSS (Cross-Site Scripting) attacks inject malicious scripts into web pages but typically do not cause automatic application downloads leading to restarts. Typosquatting (C) involves malicious websites mimicking legitimate ones via misspelled URLs. Buffer overflow (D) is an attack targeting software memory but doesn’t typically involve website compromise and automatic downloads.

This attack type is detailed in the Threats, Vulnerabilities, and Mitigations domain of SY0-701【6:Chapter 2†CompTIA Security+ Study Guide】.