ctf-postmortem

ctf-postmortem is a skill for Claude Code, Codex from yhy0/CHYing-agent. It costs 54 tokens per session (2,121 once invoked), scanned A, original, MIT.

A guide for analyzing compiled programs and solving binary challenges in a CTF, or capture-the-flag security contest. It covers inspecting program structure, finding memory bugs, tracing execution, and building exploits.

In plain words
What is it for?
Use it to inspect binary files, identify architectures and protections, decompile or debug programs, investigate memory corruption, and create scripts for challenge exploits.
Why use it?
It gives a staged process for understanding an unfamiliar executable before attempting an exploit. It also accounts for protections, packing, programming language, and useful strings.

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/yhy0/chying-agent/ctf-postmortem
Any agent
npx skills add yhy0/CHYing-agent --skill ctf-postmortem
Clone the repo
git clone --depth 1 https://github.com/yhy0/CHYing-agent

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 ctf-postmortem

README.md
[![agentmods](https://agentmods.dev/badge/skills/yhy0/chying-agent/ctf-postmortem.svg)](https://agentmods.dev/skills/yhy0/chying-agent/ctf-postmortem)
Your own site
<a href="https://agentmods.dev/skills/yhy0/chying-agent/ctf-postmortem"><img src="https://agentmods.dev/badge/skills/yhy0/chying-agent/ctf-postmortem.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,121 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00054 $0.02121
Opus 5 $0.00027 $0.01060
Sonnet 5 $0.00011 $0.00424
Haiku 4.5 $0.00005 $0.00212

Measured 5d ago against content hash 338a50d760dc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ctf-postmortem scanned grade A with 1 finding 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 5d 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.

Makes network callslowCapability

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

| `JS_BLIND` | JS 渲染内容不可见,curl 看不到真实页面 | Content-Length=0,browser 未启用 |
.claude/skills/ctf-postmortem/SKILL.md · 209 lines

How it starts

The opening of the file, as written. The whole thing — 209 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CTF 赛后复盘分析

对 CHYing Agent 在一次或多次 CTF 比赛中的表现进行系统性分析,找出失败规律,提出系统级(非题目级)优化建议。

数据来源

  • challenge 工作目录agent-work/ctf/<Category>/<challenge_dir>/
  • 关键文件
    文件 内容
    progress.md 主任务状态、攻击树、Dead Ends、当前阶段
    findings.log 所有 key findings,含 kind/status/evidence
    dumps/commands.log 执行命令历史
    dumps/checkpoints.log Reflection 检查点与停滞诊断
    result.json 最终结果(若存在)

执行流程

第一步:收集所有 challenge 目录

agent-work/ctf/
├── Web/
│   └── <challenge_dir>/
├── PWN/
├── Crypto/
├── Misc/
├── Cloud/
├── reverse/
└── tencent_cloud/

用 Glob 工具扫描所有 */*/progress.md 文件,建立题目清单。

对每道题提取:

  • 题目名:从目录名推断
  • 类别:父目录名
  • 是否解出:检查 progress.md 中是否出现 FLAG{flag{ 字样,或 findings.log 中存在 kind: flag 条目
  • 最终状态:从 progress.md 的 "Current Phase" 或最后的 Dead Ends 推断

第二步:统计解题率

输出如下统计表:

## 解题统计

总题数: N
已解出: M (M/N = XX%)
未解出: K

| 类别  | 总数 | 解出 | 解出率 |
|-------|------|------|--------|
| Web   |  X   |  X   |  XX%   |
| PWN   |  X   |  X   |  XX%   |
| Crypto|  X   |  X   |  XX%   |
| Misc  |  X   |  X   |  XX%   |
| Cloud |  X   |  X   |  XX%   |

第三步:失败题目逐题诊断

对每道未解出的题目,读取其 progress.mdfindings.log,提取:

  1. 停止原因(stop_reason):timeout / consecutive_failures / blocked / max_turns
  2. 最后阶段(Current Phase):到哪一步卡住了
  3. Dead Ends:列举所有已证实无效的方向
  4. 最后的 highest_anomaly:最有价值但未被充分利用的线索
  5. 工具使用模式:主要用了哪类工具(executor/browser/reverse/c2)
  6. 是否触发了 kb_search:findings.log 中是否有知识库搜索记录
  7. 是否使用了 browser:是否做过 JS 渲染验证

第四步:失败模式归类

将所有失败题目归入以下根因类别(一题可归多类):

根因代码 含义 识别信号
TARGET_UNREACHABLE 目标服务不可达 大量连接错误/超时,无任何有效响应
TOOL_GAP 缺少合适工具或工具用法错误 反复 exec 失败,未尝试 browser/reverse
KB_MISS 未搜索知识库,错过已知漏洞/技术 存在版本号但无 kb_search,类型为 cloud/misc
JS_BLIND JS 渲染内容不可见,curl 看不到真实页面 Content-Length=0,browser 未启用
LOOP_SAME_VECTOR 在同一攻击向量上反复尝试,未转换方向 Dead Ends 全属同一类别,攻击树分支单一
PARTIAL_CHAIN 有部分发现但未串联成完整攻击链 findings.log 有多条 confirmed 但无 exploited
TIMEOUT_TOO_EARLY 时间到了但方向是对的,只是执行不够深入 最后阶段在正确方向上但 stop_reason=timeout
RECON_SHALLOW 侦察不足,缺少关键信息就开始攻击 progress.md 缺少服务版本/路径/参数信息
REFLECT_MISSED Reflection 机制未触发或触发后未改变策略 checkpoints.log 无记录,或记录后仍重复死路
SESSION_REPEAT 多次 session 重复相同工具路径 prior_knowledge 存在但策略未变

Read the full file on GitHub · 209 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. 5d ago First seen · 209 lines · 54 tokens per session scan A 338a50d760dc

Subscribe to this mod's changes

ctf-postmortem is a skill published in the GitHub repository yhy0/CHYing-agent (554 stars, last pushed 4mo ago), licensed MIT. It adds 54 tokens to every session and 2,121 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

local-ai-agents

Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…

microsoft/ai-agents-for-beginners · 200 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens

chronicle

Analyze Copilot session history for standup reports, usage tips, session search, and session reindexing. Use when the user asks for a standup, daily summary, usage tips, workflow recommendations, wants to search or find past sessions by keyword/file/PR, wants to reindex their session store, or asks about deleting…

microsoft/vscode · 72 tokens

babysit-pr

Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…

openai/codex · 114 tokens