A service-based solution, typically offered by a third-party auditing firm or a Managed Security Service Provider (MSSP), is the most suitable choice. This model inherently provides an external perspective ("imitates the outside view of attackers") by scanning the organization's assets from the internet. These providers use enterprise-grade scanning tools that are continuously updated with the latest vulnerability information and employ advanced techniques like inference-based testing. They are designed to manage scans across multiple, geographically dispersed networks, fulfilling all the requirements stated by the e-commerce organization. The third party manages the entire assessment infrastructure, process, and reporting.

A. Inference-based assessment solution: This describes a specific testing technique used by scanning tools to deduce information, not a comprehensive solution type.
C. Tree-based assessment approach: This is a manual methodology for systematically testing network paths and components, not an automated, database-driven solution.
D. Product-based solution installed on a private network: This type of solution provides an internal perspective by default and would not accurately imitate an external attacker's view. ---

1. EC-Council. (2023). Certified Ethical Hacker (CEH) Version 13 Courseware

Module 06

"Vulnerability Analysis."

The official CEH v13 curriculum distinguishes between vulnerability assessment solutions. It describes service-based solutions as being performed by a third party from a remote location

providing an independent

outside-in perspective of the network. It explicitly contrasts this with product-based solutions

which are installed internally and provide an inside-out view. The text also identifies tree-based assessment as a manual methodology and inference-based testing as a feature of scanning logic.

2. Kim

D.

& Solomon

M. G. (2021). Fundamentals of Information Systems Security (4th ed.). Jones & Bartlett Learning.

Chapter 10

"Vulnerability Assessment and Penetration Testing

" discusses the different models for conducting assessments. It explains that engaging external security consultants (a service-based model) is a common practice for obtaining an objective

external view of an organization's security posture

which is critical for internet-facing entities like e-commerce companies.

3. Scarfone

K.

& Mell

P. (2008). Technical Guide to Information Security Testing and Assessment (NIST SP 800-115). National Institute of Standards and Technology.

Section 4.3

"Assessment Methods

" outlines various approaches. While not using the exact CEH terminology

it differentiates between assessments performed by internal staff using on-premises tools versus those conducted by external

independent parties. It notes that external assessments are crucial for understanding the exposure of publicly accessible systems

aligning with the requirements for a service-based solution.