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

DNS poisoning (also known as DNS cache poisoning) occurs when a malicious actor injects false DNS data into a DNS resolver's cache. The poisoned entry will persist for the duration of its TTL (Time To Live), which is defined in the DNS SOA (Start of Authority) record.

The SOA record contains several fields including:

Serial number

Refresh

Retry

Expire

Minimum TTL

The Minimum TTL value in the SOA record determines how long a DNS resolver should cache the DNS data — including any potentially poisoned data.

From CEH v13 Official Courseware:

Module 3: Scanning Networks

Topic: DNS Enumeration & Poisoning

CEH v13 Study Guide states:

“The SOA record includes a minimum TTL value that dictates how long DNS information should be cached by other DNS servers. If DNS cache poisoning occurs, the false information will persist until the TTL expires.”

Incorrect Options:

A: MX (Mail Exchange) defines mail servers, not TTLs.

C: NS (Name Server) specifies authoritative servers, not caching durations.

D: TIMEOUT is not a valid DNS resource record.

Ettercap is a comprehensive MITM attack tool that supports live traffic interception and content injection. It can modify HTTP streams in real time and inject malicious payloads, such as JavaScript or applets, into web traffic.

Reference – CEH v13 Official Study Guide:

Module 8: Sniffing

Quote:

“Ettercap allows attackers to intercept, analyze, and alter data on the fly, including injecting malicious content like Java applets in HTTP sessions during MITM attacks.”

Incorrect Options Explained:

A & D. Wireshark and Tcpdump are passive sniffers with no injection capability.

C. Aircrack-ng is for Wi-Fi key cracking, not traffic manipulation.

=

https://ru.wikipedia.org/wiki/DNS_spoofing

DNS spoofing is a threat that copies the legitimate server destinations to divert the domain's traffic. Ignorant these attacks, the users are redirected to malicious websites, which results in insensitive and personal data being leaked. It is a method of attack where your DNS server is tricked into saving a fake DNS entry. This will make the DNS server recall a fake site for you, thereby posing a threat to vital information stored on your server or computer.

The cache poisoning codes are often found in URLs sent through spam emails. These emails are sent to prompt users to click on the URL, which infects their computer. When the computer is poisoned, it will divert you to a fake IP address that looks like a real thing. This way, the threats are injected into your systems as well.

Different Stages of Attack of DNS Cache Poisoning:

- The attacker proceeds to send DNS queries to the DNS resolver, which forwards the Root/TLD authoritative DNS server request and awaits an answer.

- The attacker overloads the DNS with poisoned responses that contain several IP addresses of the malicious website. To be accepted by the DNS resolver, the attacker's response should match a port number and the query ID field before the DNS response. Also, the attackers can force its response to increasing their chance of success.

- If you are a legitimate user who queries this DNS resolver, you will get a poisoned response from the cache, and you will be automatically redirected to the malicious website.

CEH v13 identifies the Idle Scan as one of the most stealthy and advanced reconnaissance techniques due to its ability to avoid generating any traffic directly between the attacker and the target. Using a “zombie host,” which has predictable IP ID sequencing, the attacker forges packets so that all scan traffic appears to originate from the zombie. The IDS sees communication only between the zombie and the target, not the attacker. This allows evasion of network monitoring tools, traffic correlation systems, and intrusion detection signatures. CEH highlights Idle Scanning as a core technique for bypassing sophisticated detection controls because it leaves no direct fingerprint of the attacker. Options A and B still originate from the attacker’s IP. Option C can evade some filters but remains detectable due to packet anomalies. Only Idle Scanning provides full origin obfuscation, making it the most appropriate method for stealth port enumeration.