CEH v13 312-50v13 Book

An advanced persistent threat (APT) may be a broad term wont to describe AN attack campaign within which an intruder, or team of intruders, establishes a bootleg, long presence on a network so as to mine sensitive knowledge.

The targets of those assaults, that square measure terribly fastidiously chosen and researched, usually embrace massive enterprises or governmental networks. the implications of such intrusions square measure huge, and include:

Intellectual property thieving (e.g., trade secrets or patents)

Compromised sensitive info (e.g., worker and user personal data)

The sabotaging of essential structure infrastructures (e.g., information deletion)

Total website takeovers

Executing an APT assault needs additional resources than a regular internet application attack. The perpetrators square measure typically groups of intimate cybercriminals having substantial resource. Some APT attacks square measure government-funded and used as cyber warfare weapons.

APT attacks dissent from ancient internet application threats, in that:

They’re considerably additional advanced.

They’re not hit and run attacks—once a network is infiltrated, the culprit remains so as to realize the maximum amount info as potential.

They’re manually dead (not automated) against a selected mark and indiscriminately launched against an outsized pool of targets.

They typically aim to infiltrate a complete network, as opposition one specific half.

More common attacks, like remote file inclusion (RFI), SQL injection and cross-site scripting (XSS), square measure oftentimes employed by perpetrators to ascertain a footing in a very targeted network. Next, Trojans and backdoor shells square measure typically wont to expand that foothold and make a persistent presence inside the targeted perimeter.

Comprehensive and Detailed Explanation From CEH v13 Guide:

The Network Time Protocol (NTP) is used by systems, including Linux servers, to synchronize their clocks with a time server. If NTP fails, time discrepancies may lead to inaccurate log records and affect security monitoring.

CEH v13 Reference:

Module 17: Evading IDS, Firewalls, and Honeypots – Log Tampering

“Accurate timekeeping is essential for proper logging and correlation. NTP ensures system time is synchronized across hosts.”

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Passive reconnaissance focuses on collecting information without directly touching or interacting with the target’s systems. CEH materials stress that any action that sends network traffic to the target—such as scanning, probing, fingerprinting, or enumeration—creates logs and increases the risk of detection. Email headers, however, are considered an excellent source of passive intelligence because they reveal internal IP structures, routing paths, mail server hostnames, internal domain formats, and technology stacks without requiring interaction with the target environment. Since these headers are already in the possession of the ethical hacker through legitimate communication records, examining them does not generate traffic or trigger monitoring systems. SSL certificates and WHOIS data provide valuable external information, but they rarely disclose internal addressing schemes. Active scanning tools, such as Nmap, would immediately violate the requirement to avoid detection. Therefore, analyzing previously received email headers is the most effective and covert method for extracting internal network details during the reconnaissance phase.

Bob wants Alice to verify that the message hasn’t been tampered with. This is a use case for ensuring data integrity and authenticity. The process described matches the creation of a digital signature:

Bob computes a checksum (typically a cryptographic hash) of the message.

Then, he encrypts this checksum (hash) using his own private key.

Alice receives the message and decrypts the checksum using Bob’s public key.

If the decrypted checksum matches the hash she computes from the received message, she confirms the message’s integrity and authenticity.

This is a fundamental principle of digital signatures.

Incorrect Options:

A. Alice's private key is never used by others; it's confidential.

B. Encrypting with Alice’s public key ensures confidentiality, not authenticity.

D. Bob’s public key is used by the receiver to verify authenticity, not for encryption in this context.

Reference – CEH v13 Official Courseware:

Module 20: Cryptography

Section: “Digital Signatures”

Subsection: “Using Private Keys to Sign and Public Keys to Verify”

CEH Engage Lab: Email Signing and Verification

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