ECCouncil Updated 312-50v13 Exam Questions and Answers by rogan

The scenario describes an API vulnerability where unauthorized users are able to view, modify, or delete sensitive data by interacting with API objects. This indicates a failure in access control—specifically, a lack of Attribute-Based Access Control (ABAC) validation.

Attribute-Based Access Control (ABAC):

ABAC is an advanced access control model that evaluates access permissions based on attributes of the user, the resource, and the environment (e.g., user role, data sensitivity, location, etc.).

When ABAC is not properly implemented ("No ABAC validation"), APIs may allow users to access or manipulate objects they shouldn't have access to.

In APIs, this typically results in vulnerabilities like Insecure Direct Object Reference (IDOR), where users can tamper with object identifiers (IDs) to access or alter data that doesn’t belong to them.

This is one of the top risks highlighted by the OWASP API Security Top 10 (e.g., Broken Object Level Authorization).

Incorrect Options:

A. Code injection refers to injecting malicious code (e.g., SQLi, XSS), not improper access control.

B. Improper use of CORS (Cross-Origin Resource Sharing) may lead to unauthorized data exposure but doesn’t describe unauthorized object access in an API.

D. Business logic flaws relate to weaknesses in application workflows and rules, not direct access control failures.

Reference – CEH v13 Official Courseware:

Module 14: Hacking Web Applications

Section: "API Security Threats"

Subsection: "Access Control Failures in APIs (IDOR, BOLA, ABAC-related flaws)"

OWASP API Security Top 10: 2023 – A1: Broken Object Level Authorization

CEH iLabs and CEH Engage also demonstrate API-based attack vectors exploiting access control weaknesses.

The VRFY commands enables SMTP clients to send an invitation to an SMTP server to verify that mail for a selected user name resides on the server. The VRFY command is defined in RFC 821.

The server sends a response indicating whether the user is local or not, whether mail are going to be forwarded, and so on. A response of 250 indicates that the user name is local; a response of 251 indicates that the user name isn’t local, but the server can forward the message. The server response includes the mailbox name.

STP prevents bridging loops in a redundant switched network environment. By avoiding loops, you can ensure that broadcast traffic does not become a traffic storm.

STP is a hierarchical tree-like topology with a “root” switch at the top. A switch is elected as root based on the lowest configured priority of any switch (0 through 65,535). When a switch boots up, it begins a process of identifying other switches and determining the root bridge. After a root bridge is elected, the topology is established from its perspective of the connectivity. The switches determine the path to the root bridge, and all redundant paths are blocked. STP sends configuration and topology change notifications and acknowledgments (TCN/TCA) using bridge protocol data units (BPDU).

An STP attack involves an attacker spoofing the root bridge in the topology. The attacker broadcasts out an STP configuration/topology change BPDU in an attempt to force an STP recalculation. The BPDU sent out announces that the attacker’s system has a lower bridge priority. The attacker can then see a variety of frames forwarded from other switches to it. STP recalculation may also cause a denial-of-service (DoS) condition on the network by causing an interruption of 30 to 45 seconds each time the root bridge changes. An attacker using STP network topology changes to force its host to be elected as the root bridge.

This scenario describes steganographic sniffing, a highly sophisticated technique covered in CEH v13 Network Sniffing and Steganography. By embedding sensitive data inside legitimate image files—such as CT scans—attackers can intercept or exfiltrate patient information while avoiding detection.

Option D represents a steganography-based covert channel, which is extremely difficult to identify because:

The file appears legitimate

Standard encryption and IDS tools do not flag it

Medical images naturally contain large data volumes

Options A and B involve malware, which is more detectable. Option C involves text-based covert channels, which are easier to analyze than binary image embedding.

CEH v13 identifies steganography as one of the hardest data-hiding techniques to detect, making Option D correct.