312-50v13 Exam Dumps - Certified Ethical Hacker Exam (CEHv13)

This question focuses on API Security, Webhooks abuse, and Webshell mitigation, all of which are addressed in the CEH v13 Web Application Hacking and Security Operations modules. The most appropriate corrective action is Option D, as it directly addresses the root causes and persistence mechanisms of the compromise.

According to CEH v13, attackers frequently exploit improper input validation in APIs and insecure webhook implementations to inject malicious payloads or gain remote command execution. Webhooks, when not properly validated, can accept malicious requests that trigger backend processes, making them a common vector for API abuse.

Input validation on all API endpoints is critical to prevent injection attacks, including command injection and SQL injection. CEH v13 explicitly emphasizes validating request parameters, headers, and payload structures to prevent malicious manipulation.

Reviewing webhook payloads ensures that only trusted sources can trigger automated actions, preventing attackers from abusing webhook functionality. This includes validating signatures, enforcing authentication, and restricting allowed payload formats.

Finally, regular scanning for webshells is essential because webshells provide persistent backdoor access. CEH v13 identifies webshell detection as a key defensive measure during incident response and post-exploitation containment.

Other options are incomplete:

A WAF alone cannot detect all webshells.

IP blocking is ineffective against spoofed or cloud-based attacks.

MFA and server hardening are valuable but do not directly address webhook abuse or existing webshells.

Therefore, Option D provides the most comprehensive, CEH v13–aligned mitigation strategy.

Implementing regular firmware updates for all IoT devices is the primary recommendation to prevent DDoS attacks on the smart city project. Firmware updates can fix security vulnerabilities, patch bugs, and improve performance of the IoT devices, making them less susceptible to malware infections and botnet recruitment12. Firmware updates can also enable new security features, such as encryption, authentication, and firewall, that can protect the IoT devices from unauthorized access and data theft3. Firmware updates should be done automatically or remotely, without requiring user intervention, to ensure timely and consistent security across the IoT network4.

The other options are not as effective or feasible as firmware updates for the following reasons:

B. Deploying network intrusion detection systems (IDS) across the IoT network can help detect and alert DDoS attacks, but not prevent them. IDS can monitor network traffic and identify malicious patterns, such as high volume, spoofed IP addresses, or unusual protocols, that indicate a DDoS attack5. However, IDS cannot block or mitigate the attack, and may even be overwhelmed by the flood of traffic, resulting in false positives or missed alerts. Moreover, deploying IDS across a vast network of IoT devices can be costly, complex, and resource-intensive, as it requires dedicated hardware, software, and personnel.

C. Establishing strong, unique passwords for each IoT device can prevent unauthorized access and brute-force attacks, but not DDoS attacks. Passwords can protect the IoT devices from being compromised by hackers who try to guess or crack the default or weak credentials. However, passwords cannot prevent DDoS attacks that exploit known or unknown vulnerabilities in the IoT devices, such as buffer overflows, command injections, or protocol flaws. Moreover, establishing and managing strong, unique passwords for each IoT device can be challenging and impractical, as it requires user awareness, memory, and effort.

D. Implementing IP address whitelisting for all IoT devices can restrict network access and communication to trusted sources, but not DDoS attacks. IP address whitelisting can filter out unwanted or malicious traffic by allowing only the predefined IP addresses to connect to the IoT devices. However, IP address whitelisting cannot prevent DDoS attacks that use spoofed or legitimate IP addresses, such as reflection or amplification attacks, that bypass the whitelisting rules. Moreover, implementing IP address whitelisting for all IoT devices can be difficult and risky, as it requires constant updating, testing, and monitoring of the whitelist, and may block legitimate or emergency traffic by mistake.

According to CEH v13 Module 03: Scanning Networks, when using Nmap for service enumeration and fingerprinting, the flag to determine service version and type information is:

-sV — Version Detection Scan

nmap -sV instructs Nmap to actively connect to open ports and probe the services running on those ports. This technique helps identify:

The service name (e.g., Apache, Nginx, etc.)

The version number (e.g., Apache 2.4.54)

The OS or device details (when possible)

This is especially useful when ports like 80 (HTTP) and 443 (HTTPS) are open, as it helps determine which web server is running (e.g., Apache, IIS, Nginx) and its version — which is critical for vulnerability assessment.

Why Other Options Are Incorrect:

A. -sv

❌ Incorrect syntax. Nmap flags are case-sensitive and this is a typo. Correct flag is -sV.

B. -Pn

Skips host discovery (ping scan). It does not provide service version info.

C. -V

Displays Nmap’s version, not the service version on the target.

D. -ss

Incorrect spelling. You may have meant -sS (TCP SYN scan), which is for port scanning, not version detection.

Correct Option is A, assuming the intent is to write the correct syntax as -sV. However, strictly speaking, if this is a case-sensitive exam, and the listed option is -sv (lowercase 'v'), it would be invalid. But based on CEH exam context where minor casing issues are accepted if conceptually correct, A is the best answer.

Reference from CEH v13 Study Guide and Courseware:

Module 03 – Scanning Networks, Section: Nmap Scan Types and Options

EC-Council iLabs: Performing Version Detection Using nmap -sV

Nmap Official Docs (Referenced in CEH): https://nmap.org/book/man-version-detection.html

-h | findstr " -sV" -sV: Probe open ports to determine service/version info

https://www.infocyte.com/blog/2019/02/16/cybersecurity-101-what-you-need-to-know-about-false-positives-and-false-negatives/

False positives are mislabeled security alerts, indicating there is a threat when in actuality, there isn’t. These false/non-malicious alerts (SIEM events) increase noise for already over-worked security teams and can include software bugs, poorly written software, or unrecognized network traffic.

False negatives are uncaught cyber threats — overlooked by security tooling because they’re dormant, highly sophisticated (i.e. file-less or capable of lateral movement) or the security infrastructure in place lacks the technological ability to detect these attacks.

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.