The log data reveals millions of identical GET requests originating from a single source IP address (147.186.119.200). This pattern is characteristic of a Denial of Service (DoS) attack, where an attacker attempts to overwhelm a target system's resources (such as CPU, memory, or network bandwidth) with a flood of traffic from a single machine. The goal is to make the service, in this case, the web server, unavailable to legitimate users. The report of the server becoming unavailable confirms the success of this resource-exhaustion attack.

B. A Distributed Denial of Service (DDoS) attack is similar in goal but originates from numerous, geographically dispersed source IP addresses, not a single one as shown in the log.

C. A Cross-Site Scripting (XSS) attack involves injecting malicious scripts into a web page, which would be visible in the URL parameters or request body, not a simple GET /login/ request.

D. A Database Injection attack involves embedding malicious commands (e.g., SQL) in data input fields to manipulate a back-end database; the provided log entry shows no such malicious payload.

1. Splunk Enterprise Security Documentation: The "DoS Attack Detected" correlation search in Splunk Enterprise Security is designed to identify this exact scenario. Its logic detects an abnormally high number of events from a single source (src) to a single destination (dest) within a short time frame

which aligns perfectly with the millions of log entries from one IP.

Source: Splunk Enterprise Security

"Use Splunk Enterprise Security

" Version 7.2.0

Correlation search reference

"DoS Attack Detected".

2. Carnegie Mellon University

Software Engineering Institute (CERT Coordination Center): "A denial-of-service (DoS) attack is an attack meant to shut down a machine or network

making it inaccessible to its intended users. DoS attacks accomplish this by flooding the target with traffic or sending it information that triggers a crash. In a DoS attack

a single computer is used to launch the attack." This definition precisely describes the event in the question.

Source: CERT Coordination Center

"Understanding Denial-of-Service Attacks

" Document ID: IN-2001-01.

3. University Courseware (Stanford University): In CS 155

Computer and Network Security

DoS attacks are defined by the "one-to-one" nature of the traffic flood

contrasting with DDoS attacks which are "many-to-one." The log evidence of one IP sending millions of requests is a textbook example of a DoS attack as taught in foundational cybersecurity courses.

Source: CS 155: Computer and Network Security

Lecture 10: "Web Security Model

Network Attacks

" Stanford University.