Information Security Fundamentals

Directory services (such as LDAP or Active Directory) serve as the central repository storing user IDs, profiles, and authentication data. When users authenticate, the system queries the directory to verify their credentials, making it fundamental to authentication processes.

Password synchronization ensures that when a user changes their password on one system, the change propagates to all other systems where they have accounts. This maintains consistent passwords across LDAP, Active Directory, RADIUS, and other connected systems, unlike SSO which uses one credential for multiple systems without synchronizing passwords.

SYN Flooding is a classic Denial of Service (DoS) attack that exhausts a server's resources by flooding it with TCP SYN requests without completing the handshake. It does not involve cryptanalysis, social engineering, or repudiation.

The TEAR DROP attack exploits a vulnerability in IP fragment reassembly. It sends overlapping or malformed IP fragments that crash or hang systems when they attempt to reassemble the packet.

Kerberos authentication relies heavily on timestamps to prevent replay attacks. If the clocks on the KDC, client, and server are not synchronized, tickets will be rejected because they appear to be expired or issued in the future.

CHAP (Challenge Handshake Authentication Protocol) is a network authentication protocol that uses a three-way handshake to verify a user's identity without transmitting their password directly. The server sends a random challenge, the client responds with a hash of the challenge combined with their password, and the server verifies this hash. Options A and C are incorrect because CHAP is not about availability or using 'canonical'. Option B incorrectly uses 'Handover' instead of 'Handshake'.

Cryptanalysis is the science and practice of analyzing information systems to discover hidden aspects of the system, specifically studying methods for breaking encryption algorithms and ciphers. It is the counterpart to cryptography, which focuses on creating secure communication methods. Cryptogram refers to the encrypted text itself, steganography involves hiding messages within other content, and 'crptology' appears to be a typo.

SYN flooding attacks exploit the TCP three-way handshake mechanism where a client sends SYN, server responds with SYN-ACK, and client completes with ACK. The attacker sends many SYN packets but never completes the handshake, exhausting server resources. This attack does not target IIS or Netscape vulnerabilities specifically, and SCTP uses a four-way handshake which is not the target of SYN flooding.

CIA triad is the fundamental model of information security consisting of Confidentiality (preventing unauthorized disclosure), Integrity (preventing unauthorized modification), and Availability (ensuring authorized access when needed). Option B incorrectly uses 'accessibility' which is different from availability, Option C has incorrect terms, and Option D uses 'Access Control' which is a mechanism, not a core principle.

Passwords should be stored in hashed form using a slow, salted hash function like bcrypt, Argon2, or PBKDF2. Hashing is one-way, so even if the password database is compromised, attackers cannot easily recover the original passwords. Encryption is reversible and less secure for password storage, and plaintext storage is a critical security failure. Modern systems never store passwords in plaintext.

Steganography is the practice of concealing messages within other messages, images, or objects so that the very existence of the hidden message is not apparent to casual inspection. Unlike cryptography which hides the content of a message, steganography hides the existence of the message itself. The word derives from Greek meaning 'covered writing'. Cryptography is about encrypting messages, not hiding their existence.

Buffer overflows in programs running with administrator/root privileges are most dangerous because they can lead to complete system compromise. When an administrator-level process is exploited, the attacker gains the same high privileges as that process, allowing full control over the system. Overflowing a normal user program limits the attacker's scope, and programs 'run by the attacker' or 'run by the remote user' are nonsensical distractors in this context.

DES (Data Encryption Standard) is no longer considered secure due to its 56-bit key length, which can be brute-forced with modern computing power. It was officially withdrawn as a standard by NIST in 2005. Specialized hardware can break DES in hours or days, making it completely unsuitable for protecting sensitive data today. Modern replacements like AES should be used instead.

Digital signatures DO provide protection from tampering through their integrity verification mechanism. When a document is digitally signed, any modification after signing causes the signature verification to fail, alerting the recipient that tampering occurred. The signature is based on a cryptographic hash of the document content, so even a single bit change invalidates the signature. This is a fundamental security property of digital signatures.

Signing a document directly and signing its hash both provide the same level of data integrity protection because the signature operation mathematically operates on the hash in both cases. When you 'sign a document', the actual cryptographic operation first hashes the document then signs the hash. Explicitly hashing first just makes this process explicit. The security guarantee is identical because any change to the document changes the hash, which invalidates the signature.

One-time pads are theoretically unbreakable if implemented correctly with truly random keys that are used only once and never reused. This assumes unlimited time and resources for proper key generation and distribution. DES and Triple DES have known vulnerabilities, and Blowfish, while strong, is not provably 100% secure.

Blowfish is a symmetric-key block cipher designed by Bruce Schneier in 1993. It's known for its speed and effectiveness in encryption. Note that the correct spelling is 'Schneier', not 'Schiener' as shown in the option.

Mobile messaging devices like Blackberry and Treo continuously store emails, messages, and documents, making them repositories of confidential information. RAM is volatile memory that clears on power-off, VPNs are network tunnels not storage devices, and digital cameras store media but aren't typically business data repositories.

WPA (Wi-Fi Protected Access) replaced the broken WEP encryption and provides significantly stronger security through TKIP/AES encryption and improved authentication. WEP is notoriously insecure and easily cracked, Bluetooth has security vulnerabilities, and microwave communications isn't a standard wireless networking protocol.