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CompTIA Security+ Cram Sheet
Exam Structure (SY0-701)
- Questions: Max 90 | 90 minutes
- Passing score: 750 (on 100–900 scale)
- Question types: MCQ + Performance-based (PBQs)
- Domains: 5 domains — General Security (12%), Threats/Vulnerabilities (22%), Architecture (18%), Implementation (28%), GRC (20%)
Common Ports to Know
- 20/21 FTP (data/control)
- 22 SSH / SFTP / SCP
- 25 SMTP
- 53 DNS
- 80/443 HTTP/HTTPS
- 110/995 POP3/POP3S
- 143/993 IMAP/IMAPS
- 389/636 LDAP/LDAPS
- 3389 RDP
Attack Types — Quick Reference
- Phishing — mass email deception | Spear phishing — targeted individual | Whaling — targets executives | Vishing — voice calls
- SQL Injection — malicious SQL in input fields to manipulate databases
- XSS (Cross-Site Scripting) — injects scripts into trusted websites
- CSRF — forces authenticated user to execute unwanted actions
- Man-in-the-Middle (MitM) — intercepts communication between two parties
- Replay attack — intercepts and retransmits valid authentication data
- DoS/DDoS — floods a system to make it unavailable
- Brute force — tries all password combinations | Dictionary attack — common password wordlist
- Pass-the-hash — uses captured password hash without cracking it
- Privilege escalation — gains higher permissions than authorized
- Zero-day — exploits unknown/unpatched vulnerability
- Rootkit — hides malware at OS/kernel level
Encryption Types
- Symmetric — same key encrypt/decrypt (AES, 3DES, RC4)
- Asymmetric — public/private key pair (RSA, ECC, Diffie-Hellman)
- AES — current standard; 128/192/256-bit
- RSA — asymmetric; 2048+ bit keys recommended
- ECC — smaller keys, same strength as RSA
- Hashing — one-way (MD5 broken, SHA-256 current)
- Salting — random data added before hashing (prevents rainbow tables)
AAA Framework
- Authentication — verify identity (who you are)
- Authorization — determine permissions (what you can do)
- Accounting — log/track what was done
- MFA factors: Something you know, have, are, somewhere you are, something you do
- RADIUS — centralized AAA protocol
- TACACS+ — Cisco AAA, encrypts entire packet
PKI & Certificates
- CA (Certificate Authority) — issues digital certificates
- Root CA — top of trust chain | Intermediate CA — issues end-entity certs
- CSR — Certificate Signing Request sent to CA
- CRL — Certificate Revocation List (periodic updates)
- OCSP — Online Certificate Status Protocol (real-time revocation check)
- Certificate types: DV (domain), OV (organization), EV (extended validation)
- Wildcard cert — *.domain.com covers all subdomains
- SAN cert — multiple domains on one certificate
Network Security
- Firewall — packet filter, stateful, NGFW, WAF
- IDS — detects, alerts only | IPS — detects + blocks
- SIEM — aggregates/correlates security logs
- DMZ — buffer zone between internet and internal network
- VPN — encrypted tunnel (IPSec, SSL/TLS, L2TP)
- NAC — Network Access Control; enforces endpoint compliance
- VLAN — logical network segmentation
GRC Key Terms
- Risk = Threat × Vulnerability × Impact
- Risk acceptance — accept risk as-is
- Risk transfer — insurance, outsource
- Risk avoidance — don't do the activity
- Risk mitigation — reduce likelihood/impact
- BIA — Business Impact Analysis (RTO, RPO)
- RTO — max downtime tolerated | RPO — max data loss tolerated
- Frameworks: NIST CSF, ISO 27001, COBIT, CIS Controls
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