Cybersecurity Terminology Every Beginner Should Learn

import hashlib

def sha256_of(text: str) -> str:
    return hashlib.sha256(text.encode()).hexdigest()

original = "Pay Rs 500 to account 1234"
stored_hash = sha256_of(original)

received = "Pay Rs 5000 to account 1234"   # tampered
print("unchanged?", sha256_of(received) == stored_hash)  # False
# Integrity (the I in CIA): detect if data was changed.

def risk(likelihood: int, impact: int) -> str:
    """likelihood and impact on a 1-5 scale"""
    score = likelihood * impact
    level = "High" if score >= 15 else "Medium" if score >= 8 else "Low"
    return f"score={score} level={level}"

print("Unpatched public web server:", risk(4, 5))
print("Old laptop in locked store room:", risk(1, 2))
print("Shared admin password:", risk(4, 4))

from difflib import SequenceMatcher

TRUSTED = ["examplebank.com", "uncodemy.com"]

def suspicious(domain: str) -> list:
    hits = []
    for good in TRUSTED:
        ratio = SequenceMatcher(None, domain, good).ratio()
        if domain != good and ratio > 0.85:
            hits.append((good, round(ratio, 2)))
    return hits

for d in ["examp1ebank.com", "examplebank.com", "news-site.in"]:
    print(d, "->", suspicious(d) or "no look-alike match")

import socket

# Check common ports on YOUR OWN machine only
PORTS = {22: "SSH", 80: "HTTP", 443: "HTTPS", 3306: "MySQL", 5432: "Postgres"}

for port, name in PORTS.items():
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.settimeout(0.3)
        open_ = s.connect_ex(("127.0.0.1", port)) == 0
    print(f"{port:5} {name:8} {'OPEN' if open_ else 'closed'}")
# Fewer open ports = smaller attack surface.

# pip install bcrypt
import bcrypt

password = b"MyS3cure!Pass"
hashed = bcrypt.hashpw(password, bcrypt.gensalt())
print("stored:", hashed[:20], b"...")

print("correct login:", bcrypt.checkpw(b"MyS3cure!Pass", hashed))
print("wrong login:  ", bcrypt.checkpw(b"wrongpass", hashed))
# Hashing is one-way: systems store hashes, never plain passwords.

from collections import Counter

log = [
    "2026-11-05 10:00:01 FAIL user=asha ip=203.0.113.7",
    "2026-11-05 10:00:03 FAIL user=asha ip=203.0.113.7",
    "2026-11-05 10:00:05 FAIL user=ravi ip=203.0.113.7",
    "2026-11-05 10:00:07 FAIL user=meena ip=203.0.113.7",
    "2026-11-05 10:01:00 OK   user=ravi ip=198.51.100.4",
]
fails = Counter(l.split("ip=")[1] for l in log if " FAIL " in l)
for ip, n in fails.items():
    if n >= 3:
        print(f"ALERT: {n} failed logins from {ip} (possible password guessing)")

Term: Least privilege
Plain meaning: Give each user or system only the access it needs
Example: Support staff can view but not delete accounts
Why it matters: Limits damage from mistakes or stolen accounts
Related: Role-based access control, MFA

Core:        CIA triad, asset, threat, vulnerability, risk
Threats:     phishing, malware, ransomware, attack surface, zero-day
Protection:  encryption, hashing, MFA, least privilege, patching
Operations:  SOC, SIEM, incident, IOC, false positive

Explain each in one sentence, without notes:

1. Threat vs vulnerability vs risk
2. Encryption vs hashing
3. Why MFA stops many account attacks
4. What a SOC analyst does in a shift
5. What a false positive is and why it matters