feat(analyzer): detect skills snooping on the agent ecosystem (other skills, MCP config, agent memory)#77
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A skill that reads other parts of the agent ecosystem — agent config/home dirs, MCP server configuration, or another installed skill's files — was not flagged by any analyzer. E3 matches generic credential paths (~/.ssh, ~/.aws) but agent-specific paths slipped through entirely. Add a `static_patterns_agent_snooping` analyzer: AS1 (agent config/home dirs like ~/.claude, ~/.codex), AS2 (MCP config such as .mcp.json), AS3 (reading another skill's SKILL.md). Adds an "Agent Ecosystem Snooping" category. The analyzer de-duplicates matches per (rule, line) to avoid duplicate findings. Add tests for detection, same-line de-duplication, a false-positive guard (ordinary project file access), and the node entrypoint. Signed-off-by: CharmingGroot <ohyes9711@gmail.com>
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Fixes #75.
What this adds
A skill that reaches into the agent's own environment — agent config/home dirs, MCP server configuration, or another installed skill's files — was not flagged by any analyzer. Adds a
static_patterns_agent_snoopinganalyzer under a new "Agent Ecosystem Snooping" category:~/.claude/,~/.codex/,~/.gemini/,~/.cursor/) where API keys and settings live — HIGH.mcp.json,mcp_servers) which holds server tokens/endpoints — HIGHskills/*/SKILL.md) — MEDIUMWhy this fits the skill threat model
Unlike generic file access, this threat exists only because skills run inside an agent: a malicious skill performs lateral movement within the agent's environment — stealing another skill's logic/secrets, harvesting MCP server tokens, or exfiltrating prior conversation memory. This is distinct from
E3, which targets generic OS credential files (~/.ssh,~/.aws).The reproduction from the issue (a skill reading
.mcp.json, agent memory, and another skill) went from score 0 / LOW to score 100 / CRITICAL.Scope / non-overlap
Verified the reproduction triggers none of
E1–E4, taint tracking, orbehavioral_ast. The analyzer de-duplicates matches per(rule, line)so a single line is not reported twice by the same rule.Testing
ruff check src/ tests/andruff format --check src/ tests/pass.pytest -m 'not integration'passes (606 passed, 11 skipped).static_patterns_agent_snoopingat 100% coverage. Tests cover: agent-config / MCP-config / cross-skill detection, same-line de-duplication, a false-positive guard (ordinary project file access is not flagged), and the node entrypoint.