T09 · Insecure Skill Coding Practices
Error
- Location
src/python-bridge/index.ts:14- Finding
Path Traversal Enables Execution of Arbitrary Local Python Scripts
- Content
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{ return new Promise((resolve, reject) => { const scriptPath = path.join(PYTHON_CORE_DIR, `${scriptName}.py`); const python = spawn('python3', [scriptPath, JSON.stringify(input)]); ``` ### Technical Analysis The exported `callPython` function accepts an unrestricted `scriptName` and constructs an executable path by joining that value with `PYTHON_CORE_DIR`. The value is not checked against an allowlist and the normalized path is not verified to remain inside the intended directory. Although `spawn` is used without a shell, which prevents conventional shell metacharacter injection, directory traversal remains possible. A value containing components such as `../../` can resolve to a Python file outside `python-core`. The resulting path is passed directly to the Python interpreter. The automatically appended `.py` suffix limits the target to Python files, but it does not prevent traversal or execution of attacker-selected scripts. ### Attack Path 1. An attacker obtains access to the exported `callPython` bridge, such as through application code that exposes it or permits arbitrary bridge calls. 2. The attacker supplies a traversal value such as `../../../../tmp/payload` as `scriptName`. 3. `path.join` normalizes the path outside `PYTHON_CORE_DIR`, resulting in a target such as `/tmp/payload.py`. 4. If that Python file exists and is readable, `spawn('python3', ...)` executes it. 5. The script runs with the operating-system identity and permissions of the Node.js process. Exploitation requires the attacker to control the `scriptName` argument and identify or place an executable Python file on the local filesystem. ### Impact Asses ...[truncated 423 chars]- Remediation
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