Trust Assessment
webapp-testing received a trust score of 10/100, placing it in the Untrusted category. This skill has significant security findings that require attention before use in production.
SkillShield's automated analysis identified 6 findings: 2 critical, 3 high, 1 medium, and 0 low severity. Key findings include Arbitrary command execution, Dangerous call: subprocess.run(), Dangerous call: subprocess.Popen().
The analysis covered 4 layers: Manifest Analysis, Static Code Analysis, Dependency Graph, LLM Behavioral Safety. The Manifest Analysis layer scored lowest at 40/100, indicating areas for improvement.
Last analyzed on February 16, 2026 (commit ccf6204f). SkillShield performs automated 4-layer security analysis on AI skills and MCP servers.
Layer Breakdown
Behavioral Risk Signals
Security Findings6
| Severity | Finding | Layer | Location | |
|---|---|---|---|---|
| CRITICAL | Arbitrary command execution Python shell execution (os.system, subprocess) Review all shell execution calls. Ensure commands are static (not built from user input), use absolute paths, and are strictly necessary. Prefer library APIs over shell commands. | Manifest | webapp-testing/scripts/with_server.py:69 | |
| CRITICAL | Arbitrary command execution Python shell execution (os.system, subprocess) Review all shell execution calls. Ensure commands are static (not built from user input), use absolute paths, and are strictly necessary. Prefer library APIs over shell commands. | Manifest | webapp-testing/scripts/with_server.py:88 | |
| HIGH | Dangerous call: subprocess.run() Call to 'subprocess.run()' detected in function 'main'. This can execute arbitrary code. Avoid using dangerous functions like exec/eval/os.system. Use safer alternatives. | Static | webapp-testing/scripts/with_server.py:88 | |
| HIGH | Dangerous call: subprocess.Popen() Call to 'subprocess.Popen()' detected in function 'main'. This can execute arbitrary code. Avoid using dangerous functions like exec/eval/os.system. Use safer alternatives. | Static | webapp-testing/scripts/with_server.py:69 | |
| HIGH | Command Injection via `subprocess.Popen` with `shell=True` The `scripts/with_server.py` helper script is designed to start user-defined servers. It uses `subprocess.Popen` with `shell=True` to execute the server commands provided via the `--server` command-line argument. This allows an attacker to inject arbitrary shell commands by crafting a malicious string for the `--server` argument (e.g., `--server "npm run dev; rm -rf /"`), leading to arbitrary code execution on the host system. The `SKILL.md` explicitly instructs users to run this script with user-provided server commands, making this a directly exploitable vulnerability. Avoid using `shell=True` when executing user-controlled commands. Instead, parse the command string into a list of arguments and pass `shell=False` (the default). If shell features like `cd` or `&&` are necessary, consider using a more controlled execution environment (e.g., `subprocess.Popen(['bash', '-c', user_command_string])`) or, preferably, manage directory changes and multiple commands programmatically within Python (e.g., `os.chdir()` before `subprocess.Popen`). For example, to handle `cd backend && python server.py`, you could use `os.chdir('backend')` followed by `subprocess.Popen(['python', 'server.py'], shell=False)`. | LLM | scripts/with_server.py:68 | |
| MEDIUM | Suspicious import: socket Import of 'socket' detected. This module provides network or low-level system access. Verify this import is necessary. Network and system modules in skill code may indicate data exfiltration. | Static | webapp-testing/scripts/with_server.py:18 |
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