authbypass-authentication-flaws

authbypass-authentication-flaws is a skill for Claude Code, Codex from SecurityTalent/bugskill-ai. It costs 43 tokens per session (3,830 once invoked), scanned A, a copy of authbypass-authentication-flaws, MIT.

A security-testing guide for weaknesses in the login and account-recovery process. It covers password resets, multi-factor authentication, session boundaries, token generation, account discovery, and resistance to repeated guesses.

In plain words
What is it for?
Use it to assess sign-in, password recovery, account registration, MFA, sessions, brute-force controls, default credentials, and username exposure.
Why use it?
It helps identify ways to enter an account or bypass a login check without finding a separate flaw in the application after authentication.

Skill for Claude CodeCodex

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is **AI LOAD INSTRUCTION**: Expert authentication bypass techniques. Covers SQL injection-based login bypass, password reset flaws, token predictability, account e.

Good fit Use it to assess sign-in, password recovery, account registration, MFA, sessions, brute-force controls, default credentials, and username exposure.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/SecurityTalent/bugskill-ai
agentmods
npx agentmods add skills/securitytalent/bugskill-ai/authbypass-authentication-flaws

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 authbypass-authentication-flaws

README.md
[![agentmods](https://agentmods.dev/badge/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws/github.svg)](https://agentmods.dev/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws)
Your own site
<a href="https://agentmods.dev/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws"><img src="https://agentmods.dev/badge/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws/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 authbypass-authentication-flaws

Your own site · 80×15
<a href="https://agentmods.dev/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws"><img src="https://agentmods.dev/badge/skills/securitytalent/bugskill-ai/authbypass-authentication-flaws.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,830 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 100% copy Near-identical to another mod 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 $0.00043 $0.03830
Opus 5.5 $0.00017 $0.01532
Sonnet 5.5 $0.00009 $0.00766
Haiku 4.5 $0.00004 $0.00383

Measured 1mo ago against content hash e930a9b50792, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

authbypass-authentication-flaws 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 1mo 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

This is a copy

100% identical to authbypass-authentication-flaws — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

Awesome-Claude-Code-Agent-Skills/03-Authentication-and-Access-Control/authbypass-authentication-flaws/SKILL.md · 442 lines

How it starts

The opening of the file, as written. The whole thing — 442 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Authentication Bypass — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert authentication bypass techniques. Covers SQL injection-based login bypass, password reset flaws, token predictability, account enumeration, brute force bypass, and multi-factor auth bypass. Distinct from JWT/OAuth (covered in ../jwt-oauth-token-attacks/SKILL.md). Focus on the login mechanism itself.

0. AUTHORIZED CREDENTIAL TEST PLANNING

After reducing routing entries, default credentials, username variants, port focus, and wordlist sizing are handled here in one place.

Service-first tiny sets

Service Type First Usernames First Passwords
phpMyAdmin root, admin empty, root, phpmyadmin, admin
FTP ftp, admin, test empty, ftp, admin, 123456
SSH root, admin, service account names root, admin, seasonal variants
MySQL root, mysql empty, root, mysql
Tomcat / Java admin tomcat, admin, manager tomcat, admin, s3cret
WebLogic weblogic, admin weblogic, welcome1, admin

Username classes

Class Examples
Generic admins admin, administrator, root, test, guest
Support / ops dev, ops, sysadmin, service, backup
Name-based firstname, lastname, f.lastname, first.last
Mail-derived left side of corporate email formats
Product-based tomcat, weblogic, jenkins, gitlab

Wordlist sizing and port focus

Scenario Preferred Size Why
Default admin panel 5 to 50 passwords Defaults beat giant lists here
Internal service with known product vendor-specific small set Better signal than generic lists
Consumer login with weak controls Top 20 or Top 100 Fast verification
Rate-limited login tiny list + header/rotation strategy Preserve attempts
Offline hash cracking large dictionaries Online brute rules do not apply

Prioritize common ports and service surfaces: 80/443/8080/8443 admin panels, 22 SSH, 21 FTP, and 3306/5432/6379/27017 data or management services.

Read the full file on GitHub · 442 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. 1mo ago First seen · 442 lines · 43 tokens per session scan A e930a9b50792

Subscribe to this mod's changes

authbypass-authentication-flaws is a skill published in the GitHub repository SecurityTalent/bugskill-ai (13 stars, last pushed 21d ago), licensed MIT. It adds 43 tokens to every session and 3,830 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to authbypass-authentication-flaws, differing in 0 lines, and is treated as a copy.

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