cookie-attacks

A guide to reviewing and testing session cookies, which browsers use to keep users signed in. It covers cookie security settings, scope, lifetime, token quality, server-side session handling, and browser caching.

In plain words
What is it for?
Use it to check Secure, HttpOnly, and SameSite settings, Domain and Path scope, token predictability, expiration, and cache controls.
Why use it?
It helps find ways session tokens could be exposed, reused, guessed, or sent in unsafe situations.

Skill for Claude CodeCodex

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/securityfortech/hacking-skills/cookie-attacks
Any agent
npx skills add securityfortech/hacking-skills --skill cookie-attacks
Clone the repo
git clone --depth 1 https://github.com/securityfortech/hacking-skills

Made for: Claude Code, Codex.

Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,342 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. Scan, not verified.
Origin unknown 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 $0.00109 $0.02342
Opus 5 $0.00055 $0.01171
Sonnet 5 $0.00022 $0.00468
Haiku 4.5 $0.00011 $0.00234

Measured 2d ago against content hash bb9d64b68ca7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cookie-attacks scanned grade A 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 2d 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.

Sends data to an external URLlowData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

r = requests.post("https://TARGET/login",

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 -sI -X POST "https://TARGET/login" \
skills/web/session/cookie-attacks/SKILL.md · 188 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 2d ago First seen · 188 lines · 109 tokens per session scan A bb9d64b68ca7

Subscribe to this mod's changes

cookie-attacks is a skill published in the GitHub repository securityfortech/hacking-skills (11 stars, last pushed 5mo ago), with no licence file. It adds 109 tokens to every session and 2,342 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 2 findings (sends data to an external url, 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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