sc-ssrf

sc-ssrf is a skill for Claude Code, Codex from ersinkoc/security-check. It costs 26 tokens per session (851 once invoked), scanned C, original, MIT.

A source-code checker for Server-Side Request Forgery, or SSRF. SSRF happens when an attacker can influence a server into sending a web request to an internal service, private network address, or cloud metadata endpoint.

In plain words
What is it for?
Use it to trace user input into server-side HTTP requests. It checks common request libraries and looks for both full and partial control of a request URL or host.
Why use it?
It helps find unsafe URL fetching that could expose internal systems or sensitive cloud information through the application server.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Install

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.

agentmods
npx agentmods add skills/ersinkoc/security-check/sc-ssrf
Any agent
npx skills add ersinkoc/security-check --skill sc-ssrf
Clone the repo
git clone --depth 1 https://github.com/ersinkoc/security-check

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for sc-ssrf

README.md
[![agentmods](https://agentmods.dev/badge/skills/ersinkoc/security-check/sc-ssrf.svg)](https://agentmods.dev/skills/ersinkoc/security-check/sc-ssrf)
Your own site
<a href="https://agentmods.dev/skills/ersinkoc/security-check/sc-ssrf"><img src="https://agentmods.dev/badge/skills/ersinkoc/security-check/sc-ssrf.svg" alt="Measured on agentmods" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 851 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00026 $0.00851
Opus 5 $0.00013 $0.00426
Sonnet 5 $0.00005 $0.00170
Haiku 4.5 $0.00003 $0.00085

Measured 6d ago against content hash 748a28de333e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade C, and why

sc-ssrf scanned grade C 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 6d 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 endpointhighServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

- AWS: `http://169.254.169.254/latest/meta-data/`

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

"requests.get(", "requests.post(", "urllib.request.urlopen(",
skills/sc-ssrf/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SC: Server-Side Request Forgery (SSRF)

Purpose

Detects SSRF vulnerabilities where user-controlled input influences server-side HTTP requests, enabling attackers to access internal services, cloud metadata endpoints, and private network resources. Covers direct SSRF, blind SSRF, DNS rebinding, and partial SSRF through header injection.

Activation

Called by sc-orchestrator during Phase 2. Runs against all web applications and APIs.

Phase 1: Discovery

Keyword Patterns to Search

"requests.get(", "requests.post(", "urllib.request.urlopen(",
"http.Get(", "http.Post(", "http.NewRequest(",
"fetch(", "axios.get(", "axios.post(", "got(",
"curl_exec(", "file_get_contents(", "fopen(",
"HttpClient", "WebClient", "HttpWebRequest",
"RestTemplate", "WebClient.create(", "OkHttpClient"

Data Flow: User Input → HTTP Request URL

# VULNERABLE
url = request.GET['url']
response = requests.get(url)  # User controls entire URL

# VULNERABLE: Partial SSRF
host = request.GET['host']
response = requests.get(f"https://{host}/api/data")  # User controls host

# SAFE: URL allowlist
ALLOWED_HOSTS = ['api.example.com', 'cdn.example.com']
parsed = urlparse(request.GET['url'])
if parsed.hostname not in ALLOWED_HOSTS:
    return HttpResponseForbidden()
response = requests.get(request.GET['url'])

Cloud Metadata Endpoints

Flag any request that could reach:

  • AWS: http://169.254.169.254/latest/meta-data/
  • GCP: http://metadata.google.internal/
  • Azure: http://169.254.169.254/metadata/instance

IP Bypass Techniques to Check

When blocklists are used, verify they catch:

  • Decimal: 2130706433 (127.0.0.1)
  • Hex: 0x7f000001
  • Octal: 0177.0.0.1
  • IPv6: [::1], [::ffff:127.0.0.1]
  • DNS rebinding: attacker domain resolving to internal IP

Severity Classification

  • Critical: SSRF accessing cloud metadata or internal admin services
  • High: SSRF to arbitrary internal hosts, blind SSRF with out-of-band confirmation
  • Medium: SSRF with limited impact (port scanning), partial URL control
  • Low: SSRF with strong allowlist that may have minor bypass

Read the full file on GitHub · 92 lines

Changes

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.

  1. 6d ago First seen · 92 lines · 26 tokens per session scan C 748a28de333e

Subscribe to this mod's changes

sc-ssrf is a skill published in the GitHub repository ersinkoc/security-check (56 stars, last pushed 2mo ago), licensed MIT. It adds 26 tokens to every session and 851 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C 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 2026-08-30.

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