saml-sso-assertion-attacks

saml-sso-assertion-attacks is a skill for Claude Code, Codex from yaklang/hack-skills. It costs 44 tokens per session (469 once invoked), scanned A, original, MIT.

A security testing guide for SAML, the XML-based standard used by many companies for single sign-on. It explains how to check whether login assertions and identity-provider trust are validated correctly.

In plain words
What is it for?
Use it to assess SAML login flows, assertion signatures, audience and recipient checks, ACS endpoints, issuer trust, replay protection, account mapping, and XML parsing.
Why use it?
It helps find authentication flaws caused by accepting altered, misdirected, replayed, or incorrectly signed login data.

Skill for Claude CodeCodex

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

Good fit Use it to assess SAML login flows, assertion signatures, audience and recipient…

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Install with agentmods
npx agentmods add skills/yaklang/hack-skills/saml-sso-assertion-attacks
About the project

HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.

yaklang/hack-skills · 2,098 stars · on GitHub

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.

Any agent
npx skills add yaklang/hack-skills --skill saml-sso-assertion-attacks
Clone the repo
git clone --depth 1 https://github.com/yaklang/hack-skills

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 saml-sso-assertion-attacks

README.md
[![agentmods](https://agentmods.dev/badge/skills/yaklang/hack-skills/saml-sso-assertion-attacks.svg)](https://agentmods.dev/skills/yaklang/hack-skills/saml-sso-assertion-attacks)
Your own site
<a href="https://agentmods.dev/skills/yaklang/hack-skills/saml-sso-assertion-attacks"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/saml-sso-assertion-attacks.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 469 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00044 $0.00469
Opus 5 $0.00022 $0.00234
Sonnet 5 $0.00009 $0.00094
Haiku 4.5 $0.00004 $0.00047

Measured 3d ago against content hash f8c00817762b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

saml-sso-assertion-attacks scanned grade A with 0 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 3d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

skills/saml-sso-assertion-attacks/SKILL.md · 41 lines

What it actually says

SKILL: SAML SSO and Assertion Attacks — Signature Validation, Binding, and Trust Confusion

AI LOAD INSTRUCTION: Use this skill when the target uses SAML-based SSO and you need to validate assertion trust: signature coverage, audience and recipient checks, ACS handling, XML parsing weaknesses, and IdP/SP confusion.

1. WHEN TO LOAD THIS SKILL

Load when:

  • Enterprise SSO uses SAML requests or responses
  • You see SAMLRequest, SAMLResponse, XML assertions, or ACS endpoints
  • Login flows involve an external IdP and browser POST/redirect binding

2. HIGH-VALUE MISCONFIGURATION CHECKS

Theme What to Check
signature validation unsigned assertion accepted, wrong node signed, signature wrapping
audience and recipient weak Audience, Recipient, Destination, or ACS validation
issuer trust wrong IdP accepted or multi-tenant issuer confusion
replay and freshness missing InResponseTo, weak NotBefore / NotOnOrAfter enforcement
account mapping email-only binding, case folding, unverified attributes
XML parser behavior XXE-like parser issues or unsafe transforms around SAML documents

3. QUICK TRIAGE

  1. Capture one full login round trip.
  2. Inspect which XML nodes are signed and which attributes drive account binding.
  3. Compare SP-initiated and IdP-initiated flows.
  4. Test replay, altered attributes, and assertion placement confusion.
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. 3d ago First seen · 41 lines · 44 tokens per session scan A f8c00817762b

Subscribe to this mod's changes

saml-sso-assertion-attacks is a skill published in the GitHub repository yaklang/hack-skills (2,098 stars, last pushed 2mo ago), licensed MIT. It adds 44 tokens to every session and 469 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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