Ace Your 312-50v13 CEH v13 Exam

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.

From CEH v13 Module 03: Scanning Networks, OS fingerprinting with Nmap (using the -O option) requires privileged access to craft raw packets (especially SYN, ACK, and ICMP). On Unix/Linux systems:

Root privileges are mandatory to perform TCP/IP stack fingerprinting.

If Nmap is run as a normal user, it fails to initiate OS scanning and exits with a message like “QUITTING!”.

So, in this case, the scan fails because the shell opened does not have elevated (root) privileges.

Cross-site request forgery (also known as CSRF) is a web security vulnerability that allows an attacker to induce users to perform actions that they do not intend to perform.

This is done by making a logged in user in the victim platform access an attacker controlled website and from there execute malicious JS code, send forms or retrieve "images" to the victims account.

In order to be able to abuse a CSRF vulnerability you first need to find a relevant action to abuse (change password or email, make the victim follow you on a social network, give you more privileges...). The session must rely only on cookies or HTTP Basic Authentication header, any other header can't be used to handle the session. An finally, there shouldn't be unpredictable parameters on the request.

Several counter-measures could be in place to avoid this vulnerability. Common defenses:

- SameSite cookies: If the session cookie is using this flag, you may not be able to send the cookie from arbitrary web sites.

- Cross-origin resource sharing: Depending on which kind of HTTP request you need to perform to abuse the relevant action, you may take int account the CORS policy of the victim site. Note that the CORS policy won't affect if you just want to send a GET request or a POST request from a form and you don't need to read the response.

- Ask for the password user to authorise the action.

- Resolve a captcha

- Read the Referrer or Origin headers. If a regex is used it could be bypassed form example with:

(ends with the url)

(starts with the url)

- Modify the name of the parameters of the Post or Get request

- Use a CSRF token in each session. This token has to be send inside the request to confirm the action. This token could be protected with CORS.

Passive OS fingerprinting involves observing traffic from a remote host and analyzing it to infer details about the operating system without actively sending packets or probes. This is useful in stealthy reconnaissance where avoiding detection is critical.

tcpdump is a packet analyzer that captures traffic in real time. By analyzing certain TCP/IP header fields such as TTL (Time-To-Live), window size, TCP options, and DF (Don't Fragment) flags, attackers can passively deduce the operating system of the target host.

CEH v13 Guide states:

“Passive fingerprinting tools like tcpdump and Wireshark allow the attacker to capture packets and analyze them for OS-specific traits, making it possible to identify the OS without sending packets to the target system.”

Reference – CEH v13 Study Guide:

Module 02: Footprinting and Reconnaissance, Section: “OS Fingerprinting Techniques”, Subsection: “Passive OS Fingerprinting”

Incorrect Options Explained:

A: nmap is primarily an active scanning tool (though it has limited passive capabilities).

C: tracert is used for tracing packet routes, not OS fingerprinting.

D: ping checks host availability and latency, not OS details.

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