CEH methodology emphasizes validating and researching identified vulnerabilities to determine exploitability, patch status, and business impact. Even medium-risk findings require investigation to assess their real severity.

CEH methodology stresses prioritization based on risk, exploitability, and business impact. High-severity vulnerabilities-especially those related to outdated or unsupported server software-are frequently associated with known, publicly documented exploits. The proper next step after identifying such vulnerabilities is to confirm exploitability safely, typically by researching available exploit code, validating version-specific weaknesses, and determining whether the vulnerability can be successfully leveraged under the defined scope of engagement. CEH highlights that exploitation attempts must be evidence-driven, not arbitrary, and focusing on high-risk vulnerabilities allows testers to demonstrate meaningful security impacts.
Brute-forcing (Option A) is unnecessary and high-noise. Ignoring or deprioritizing the high-risk finding (Options B and C) contradicts CEH risk-based assessment principles. Therefore, verifying exploitability of the high-risk vulnerability is the correct step.

According to CEH v13 Mobile, IoT, and OT Hacking, Advanced Persistent Threat (APT) groups prioritize stealth, persistence, and long-term control. In IoT environments, the most attractive and effective entry point is firmware-level zero-day vulnerabilities.
IoT devices often:
Run outdated or proprietary firmware
Lack regular patching mechanisms
Operate with high privileges
Have minimal monitoring
Exploiting a zero-day vulnerability in firmware allows attackers to gain deep, persistent access that survives reboots and avoids traditional security controls. This aligns directly with APT objectives.
Credential theft (Option B) is common but less reliable for IoT systems. Encrypted MitM (Option C) is complex and less persistent. DDoS (Option D) disrupts services but does not provide control.
CEH v13 explicitly identifies firmware exploitation as the primary APT vector in IoT and OT environments.
Therefore, Option A is correct.

This scenario represents a Tautology-Based SQL Injection, a fundamental SQL injection technique covered under the Web Application Hacking module in the CEH v13 curriculum. The defining characteristic of this attack is the injection of a condition that always evaluates to TRUE, thereby bypassing authentication or authorization controls.
In the given example, the injected input 1 OR 'T'='T'; -- manipulates the logical condition of the SQL query. A typical vulnerable login query may resemble:
SELECT * FROM users WHERE user_id = 1 AND password = 'input';
When the attacker submits the injected payload, the resulting SQL statement becomes:
SELECT * FROM users WHERE user_id = 1 OR 'T'='T'; --';
The expression 'T'='T' is a tautology, meaning it always evaluates to TRUE regardless of context. As a result, the database returns records without properly validating the user's credentials, granting unauthorized access.
According to EC-Council CEH v13, tautology-based SQL injection is classified as a Boolean-based injection technique where attackers exploit improper input validation to alter the logical flow of SQL queries. This attack does not depend on database error messages (as in Error-Based SQL Injection), does not extract data using UNION statements (Union-Based SQL Injection), and does not rely on response delays (Time-Based Blind SQL Injection).
CEH v13 emphasizes that such attacks are especially effective against login forms and authentication mechanisms when developers fail to implement input sanitization, parameterized queries, or prepared statements. This attack is one of the most common and exam-tested SQL injection types because it clearly demonstrates how flawed logic can compromise application security without advanced techniques.
Understanding tautology-based SQL injection is critical for ethical hackers, as it forms the foundation for identifying and mitigating more complex SQL injection variants.