Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add uphiago/recon-skills --skill hunt-host-headergit clone --depth 1 https://github.com/uphiago/recon-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/uphiago/recon-skills/hunt-host-header)<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-host-header"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-host-header/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-host-header"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-host-header.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Server-Side Request Forgery · line 171 Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
- medium Data Exfiltration · line 85 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 107 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00157 | $0.04304 |
| Opus 5 | $0.00078 | $0.02152 |
| Sonnet 5 | $0.00031 | $0.00861 |
| Haiku 4.5 | $0.00016 | $0.00430 |
Grade B, and why
hunt-host-header scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Cloud metadata endpointmediumServer-side request forgery
One request to 169.254.169.254 can return temporary IAM credentials.
-H "Host: metadata.google.internal" -H "Metadata-Flavor: Google" Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl --max-time 30 --connect-timeout 10 -s -X POST https://$TARGET/forgot-password \ How it starts
The opening of the file, as written. The whole thing — 301 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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 noALLOWED_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-Hostinto 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: [REDACTED_IP](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-URLto override the routed path → reach/adminor internal endpoints the edge ACL thought it blocked. (Different layer from routing SSRF — see Phase 3.) - OAuth/OIDC poisoning — Host drives
redirect_urior the OIDCissuer/ discovery doc → auth-code or token theft → ATO.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 301 lines · 157 tokens per session scan B 4521e87c1a85
hunt-host-header is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 157 tokens to every session and 4,304 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it B with 2 findings (cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other skills, from other repositories
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Hunt API security misconfiguration — mass assignment, prototype pollution, HTTP verb tampering. Mass assignment: send {isadmin:true, role:admin, verified:true} on profile/account/reset endpoints — server blindly applies. JWT signature/crypto forging (alg:none, key confusion, kid/jku) is owned by hunt-jwt-crypto; this…
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Detect and test for OWASP API3:2023 Broken Object Property Level Authorization vulnerabilities including excessive data exposure and mass assignment attacks.
detecting-shadow-api-endpoints
Discover and inventory shadow API endpoints that operate outside documented specifications using traffic analysis, code scanning, and API discovery platforms.