Managed Detection and Response (MDR) is a cybersecurity service that provides organizations with threat hunting, monitoring, and response capabilities delivered by a third-party vendor. The service leverages a combination of technologies and human expertise to perform incident management and protect an organization's assets. The scenario's description of a "third-party vendor with multiple tools to protect its assets" directly aligns with the definition of an MDR service.

A. PaaS: Platform as a Service is a cloud computing model that provides a platform for developing, running, and managing applications, not a security incident management service.

B. EDR: Endpoint Detection and Response is a specific security technology solution focused on monitoring and responding to threats on endpoints (e.g., workstations, servers), not a comprehensive managed service type.

D. XDR: Extended Detection and Response is a technology platform that unifies security data from multiple sources (endpoints, network, cloud). While an MDR service may use XDR, XDR itself describes the technology, not the outsourced service model.

1. MDR Definition: Soua

R.

& Seara

F. (2022). A Survey on Managed Detection and Response. ACM Computing Surveys

55(3)

1–37. https://doi.org/10.1145/3522766. The paper defines MDR as "a managed cybersecurity service that provides organizations with threat hunting services and responds to threats once they are discovered." (Section 2

para. 1).

2. PaaS Definition: Mell

P.

& Grance

T. (2011). The NIST Definition of Cloud Computing (Special Publication 800-145). National Institute of Standards and Technology. https://doi.org/10.6028/NIST.SP.800-145. Page 2 defines Platform as a Service (PaaS) as the capability to "deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages

libraries

services

and tools supported by the provider."

3. EDR/XDR Distinction: Büttner

K.

Happe

L.

& Klesel

M. (2023). From EDR to XDR: A Systematic Literature Review. In Proceedings of the 18th International Conference on Availability

Reliability and Security (ARES '23). Association for Computing Machinery

New York

NY

USA

Article 120

1–10. https://doi.org/10.1145/3600160.3600229. The paper distinguishes EDR as endpoint-focused

while XDR "extends the concepts of EDR to other data sources" (Section 3.2). This highlights them as technology types

contrasting with the service model of MDR.