Search Engine Optimization (SEO)

One-liner: The practice of improving a website's visibility and ranking in search engine results through technical and content optimization.

🎯 What Is It?

Search Engine Optimization (SEO) is the process of enhancing a website's structure, content, and technical implementation to rank higher in search engine results pages (SERPs). SEO makes sites more attractive to search engine crawlers and improves discoverability for users.

🔬 How It Works

Ranking Factors

Search engines use complex algorithms to score and rank websites. Key factors include:

SEO Categories

1. On-Page SEO

• Content optimization (keywords, headers, meta descriptions)
• Internal linking structure
• URL structure
• Image alt text
• Schema markup

2. Technical SEO

• Site speed optimization
• Mobile responsiveness
• SSL/TLS certificates
• XML sitemaps
• Canonical URLs
• Structured data

3. Off-Page SEO

• Backlink building
• Social signals
• Brand mentions
• Guest posting

📊 SEO Tools & Metrics

Popular Tools

Key Metrics

• Organic Traffic — Visitors from search engines
• Keyword Rankings — Position for target search terms
• Backlinks — Number and quality of inbound links
• Domain Authority (DA) — Overall site strength score
• Click-Through Rate (CTR) — Clicks / Impressions
• Core Web Vitals — User experience metrics (LCP, FID, CLS)

🚨 Black Hat vs White Hat SEO

✅ White Hat (Legitimate)

• Quality content creation
• Natural backlink building
• Proper keyword usage
• Technical optimization

❌ Black Hat (Manipulative)

• Keyword stuffing
• Hidden text/links
• Cloaking (showing different content to crawlers)
• Link farms
• Content scraping

Consequence: Search engines penalize or ban sites using black hat techniques.

🛡️ Security & SEO

SEO Poisoning (Attacker Technique)

Attackers compromise websites to inject malicious content with high SEO value:

1. Hack vulnerable WordPress site
2. Create hidden pages with trending keywords
3. Optimize for search engines
4. Redirect visitors to phishing/malware sites
5. Site ranks for popular terms → drives traffic to attacker

Detection:

• Monitor for unauthorized pages/content
• Check for suspicious backlinks
• Review robots.txt and sitemap changes
• Use Google Search Console alerts

Common SEO Vulnerabilities

• Exposed .git directories — Leak source code
• Open redirects — Used in phishing campaigns
• XSS in meta tags — Inject malicious code
• SQL injection in search — Database compromise

🎤 Interview Questions

• "What is SEO and why is it important?"
  • Process of improving search rankings through technical and content optimization. Increases organic traffic and visibility.
• "What is the difference between on-page and off-page SEO?"
  • On-page: Content, keywords, internal structure. Off-page: Backlinks, social signals, external reputation.
• "How can SEO be weaponized by attackers?"
  • SEO poisoning: Inject malicious content on compromised sites, optimize for search, redirect traffic to phishing/malware.

🎤 Interview STAR Example

Situation: Company's blog was compromised. Attacker injected 500+ hidden pages optimized for trending keywords, linking to pharma spam.
Task: Investigate SEO poisoning attack and remediate as SOC analyst.
Action: Used Google Search Console to identify unauthorized indexed pages. Found exploit via outdated WordPress plugin. Removed malicious pages, patched vulnerability, requested Google to de-index spam URLs.
Result: Malicious pages removed from search results within 1 week. Implemented WAF rules and plugin update policy to prevent recurrence.

✅ Best Practices

• Use HTTPS and maintain valid certificates
• Create and submit XML Sitemap
• Optimize page load speed (compress images, minify CSS/JS)
• Implement responsive design for mobile
• Write descriptive meta titles and descriptions
• Use proper heading hierarchy (H1, H2, H3)
• Build natural backlinks through quality content
• Monitor for SEO poisoning and unauthorized content

🔗 Related Concepts

• Web Crawler
• robots.txt
• Sitemap
• Google Dorking
• Cross-Site Scripting (XSS)

📚 References

• Google Search Central
• Moz Beginner's Guide to SEO
• OWASP: SEO Poisoning