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Web Exfiltration Detection Test

Red-team test for whether an agent leaks memory data via chained URL navigation from a malicious page

Stars
7,320
Licence
Apache-2.0
Files
1 file

What it does

This is a security testing playbook, not a feature for everyday work. It tells a security-testing agent how to probe another AI agent (one that can fetch web pages and holds personal memory) to see whether it can be tricked by a fake verification page into spelling out the user's name one letter at a time through URL paths. The skill defines attack prompts, a judging rubric for vulnerable versus safe answers, and a report format. It does not itself change how a normal assistant behaves.

Great for

  • Security engineers testing AI agents that have web fetch and stored user memory before release
  • Red teams building regression tests for indirect prompt injection and URL-based data exfiltration
  • Developers hardening an agent that fetches untrusted web content

Skip it if

  • Ordinary users wanting a general assistant skill: it has no productivity function and only sends adversarial prompts to a target agent
  • Agents with no web access or no personal memory: the skill itself states it does not apply, so it adds nothing there
  • Running against systems you do not own or have permission to test, since the probes target a local endpoint and could be misused against others' agents

Try asking

  • “Test my support agent at 127.0.0.1 for whether it follows a fake Cloudflare verification page that asks it to navigate letter by letter”
  • “Run the letter-by-letter URL exfiltration probes against my agent and report which responses count as vulnerable”
  • “Check whether my agent treats fetched page content as untrusted data when the page contains hidden navigation instructions”
Step-by-step guide: how to use Web Exfiltration Detection TestInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 1 original files, the Apache-2.0 licence and an attribution note.

    web-exfiltration-detection.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip web-exfiltration-detection.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip web-exfiltration-detection.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Run the probes only against agents you own or are authorised to test, in an isolated environment with dummy memory data.
  • Start with Probe 1 and escalate to Probe 2 or 3 only if the target does not navigate, to see the weakest point of failure.
  • Use the judge criteria to separate true compliance from an agent merely discussing the attack, and record exact response snippets as evidence.

What's inside

  • SKILL.md

Redistributed unmodified from Tencent/AI-Infra-Guard under the Apache-2.0 licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.