web-vuln-saml-sso

web-vuln-saml-sso is a skill for Claude Code, Codex from woohyun212/security-skill. It costs 22 tokens per session (1,925 once invoked), scanned B, original, MIT.

A security-testing guide for SAML-based single sign-on, a login system that lets one identity service authenticate users across applications. It checks whether an application incorrectly accepts altered or replayed login messages.

In plain words
What is it for?
Testing SAML identity providers and applications for XML Signature Wrapping, removed signatures, injected comments, replay, XXE, and incorrect destination URL handling.
Why use it?
It helps find weaknesses that could let an attacker bypass login checks, alter identity information, or reuse an old login response.

Skill for Claude CodeCodex

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

Good fit Testing SAML identity providers and applications for XML Signature Wrapping, removed signatures, injected comments, replay, XXE, and incorrect destination URL handling.

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Install with agentmods
npx agentmods add skills/woohyun212/security-skill/web-vuln-saml-sso
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 woohyun212/security-skill --skill web-vuln-saml-sso
Clone the repo
git clone --depth 1 https://github.com/woohyun212/security-skill

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 web-vuln-saml-sso

README.md
[![agentmods](https://agentmods.dev/badge/skills/woohyun212/security-skill/web-vuln-saml-sso/github.svg)](https://agentmods.dev/skills/woohyun212/security-skill/web-vuln-saml-sso)
Your own site
<a href="https://agentmods.dev/skills/woohyun212/security-skill/web-vuln-saml-sso"><img src="https://agentmods.dev/badge/skills/woohyun212/security-skill/web-vuln-saml-sso/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.

agentmods 80×15 button for web-vuln-saml-sso

Your own site · 80×15
<a href="https://agentmods.dev/skills/woohyun212/security-skill/web-vuln-saml-sso"><img src="https://agentmods.dev/badge/skills/woohyun212/security-skill/web-vuln-saml-sso.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,925 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 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 $0.00022 $0.01925
Opus 5 $0.00011 $0.00962
Sonnet 5 $0.00004 $0.00385
Haiku 4.5 $0.00002 $0.00193

Measured 11d ago against content hash 9a9cb3fae4fe, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade B, and why

web-vuln-saml-sso 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 11d 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.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

| `xmllint` not found | libxml2-utils not installed | `sudo apt install libxml2-utils` |

Makes network callslowCapability

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

- `curl` must be installed
web-vuln-saml-sso/SKILL.md · 179 lines

How it starts

The opening of the file, as written. The whole thing — 179 lines — stays where its author put it; the contents beside it link to each section on GitHub.

What this skill does

Detects vulnerabilities in SAML-based Single Sign-On implementations by intercepting and manipulating SAML responses. Tests for XML Signature Wrapping (XSW variants XSW1–XSW8), signature removal/stripping, NameID comment injection, SAML replay attacks, XXE in SAML responses, and Assertion Consumer Service (ACS) URL manipulation.

When to use

  • When auditing a web application that uses SAML 2.0 for authentication or federation
  • When testing an Identity Provider (IdP) or Service Provider (SP) for SSO weaknesses
  • When evaluating whether SAML signature validation can be bypassed to authenticate as an arbitrary user
  • When checking for XML-level injection or replay vulnerabilities in SSO flows

Prerequisites

  • curl must be installed
  • base64 (GNU coreutils) must be available
  • xmllint (from libxml2-utils) must be installed for XML parsing: apt install libxml2-utils
  • Ability to intercept and replay SAML responses (browser proxy or captured assertion)
  • A valid SAML response from a legitimate authentication flow

Inputs

Variable Description Example
ACS_URL Assertion Consumer Service URL (SP endpoint that receives SAML response) https://sp.example.com/saml/acs
SAML_RESPONSE_B64 Base64-encoded SAML response captured from a valid login PHNhbWxwOl...
TARGET_USER Username/email to impersonate in tests [email protected]
LEGITIMATE_USER Username of the account used to obtain the real assertion [email protected]

Workflow

Step 1: Identify SAML endpoints and decode the response

ACS_URL="https://sp.example.com/saml/acs"
SAML_RESPONSE_B64="PHNhbWxwOl..."
TARGET_USER="[email protected]"
LEGITIMATE_USER="[email protected]"

WORK_DIR=$(mktemp -d /tmp/saml_test_XXXXXX)
echo "[+] Working directory: $WORK_DIR"

# Decode and pretty-print the SAML response
echo "$SAML_RESPONSE_B64" | base64 -d > "$WORK_DIR/saml_original.xml"
xmllint --format "$WORK_DIR/saml_original.xml" > "$WORK_DIR/saml_pretty.xml" 2>/dev/null \
  || cp "$WORK_DIR/saml_original.xml" "$WORK_DIR/saml_pretty.xml"

echo "=== Step 1: SAML response structure ==="
grep -E "<(saml:|samlp:)?(Issuer|NameID|Conditions|AudienceRestriction|Audience|AuthnStatement|AttributeStatement|Signature)" \
  "$WORK_DIR/saml_pretty.xml" | head -20

echo ""
echo "[+] NameID value:"
grep -oP '(?<=<saml:NameID[^>]*>)[^<]+' "$WORK_DIR/saml_pretty.xml" | head -3

Read the full file on GitHub · 179 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 11d ago First seen · 179 lines · 22 tokens per session scan B 9a9cb3fae4fe

Subscribe to this mod's changes

web-vuln-saml-sso is a skill published in the GitHub repository woohyun212/security-skill (21 stars, last pushed 4mo ago), licensed MIT. It adds 22 tokens to every session and 1,925 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 2 findings (asks for root, 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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