CompTIA Security+ (SY0-601) - Core Principles

A DDoS attack is a malicious attempt to disrupt the normal traffic of a targeted server, service, or network by overwhelming the target or its surrounding infrastructure with a flood of internet traffic from multiple compromised computer systems (botnet).

Phishing is a social engineering technique where attackers attempt to trick individuals into revealing sensitive information (e.g., usernames, passwords, credit card details) or installing malware by masquerading as a trustworthy entity in an electronic communication, often via email. Characteristics include urgent language, suspicious links, and generic greetings.

Ransomware is a type of malware that encrypts a victim's files, making them inaccessible. The attacker then demands a ransom payment (usually in cryptocurrency) in exchange for the decryption key. It often spreads via phishing emails or exploiting vulnerabilities.

Social engineering is the psychological manipulation of people into performing actions or divulging confidential information. It relies on human error and trust rather than technical exploits, often used to gain unauthorized access to systems or data.

A zero-day exploit is an attack that takes advantage of a software vulnerability that is unknown to the vendor or for which no patch has been released. Attackers exploit the 'zero days' the vendor has had to fix it, making these attacks particularly dangerous.

AES is a symmetric encryption algorithm widely used for securing data. It uses the same key for both encryption and decryption, making it efficient for bulk data encryption. It replaced DES as the U.S. government standard.

RSA is an asymmetric (public-key) encryption algorithm. It uses a pair of keys: a public key for encryption and a private key for decryption. It's commonly used for secure data transmission, digital signatures, and key exchange.

The primary purpose of cryptographic hashing is to ensure data integrity. A hash function takes an input (or 'message') and returns a fixed-size alphanumeric string (the 'hash value' or 'digest'). Any change to the input will result in a different hash value, allowing detection of tampering.