T03 · Remote Payload Retrieval and Execution
- Location
- INSTALL.md:210
- Finding
- Unverified Remote Installer Is Piped Directly Into a Shell<![CDATA[ ## Vulnerability Details **File Location**: `INSTALL.md:210-216` **Vulnerability Type**: Remote payload retrieval and immediate execution **Risk Level**: Critical ### Vulnerable Code ```bash # Ubuntu/Debian sudo apt install python3.8 # Or use pyenv curl https://pyenv.run | bash pyenv install 3.8.10 pyenv global 3.8.10 ``` ### Technical Analysis The installation guide instructs users to download a mutable script from `https://pyenv.run` and pipe it directly into `bash`. The response is neither inspected nor pinned to a reviewed version, and no cryptographic signature or checksum is verified. Although pyenv is a legitimate project, this installation pattern makes the code ultimately executed on the host depend on the remote server's response at installation time. The effective payload can therefore change after the Skill itself has been reviewed. ### Attack Path 1. A user follows the Python troubleshooting instructions. 2. `curl` retrieves the current response from `pyenv.run`. 3. The response is immediately interpreted by `bash`. 4. If the remote service, publishing pipeline, DNS resolution, or network path is compromised, attacker-supplied shell commands execute with the invoking user's privileges. 5. Those commands can modify user startup files, install additional payloads, access user-readable data, or establish persistence. ### Impact Assessment Successful exploitation provides arbitrary command execution as the user running the command. If the command is run from a privileged shell, the payload receives the same elevated privileges. At minimum, it may access the user's files, environment, credentials, shell configuration, and development workspace. ]]>
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the `curl | bash` pipeline from the installation guide. 2. Prefer a trusted operating-system package where available. 3. If pyenv is necessary, pin a reviewed release or commit. 4. Download the installer separately rather than executing it immediately: ```bash curl --fail --proto '=https' --tlsv1.2 \ --output pyenv-installer \ https://raw.githubusercontent.com/pyenv/pyenv-installer/<PINNED_COMMIT>/bin/pyenv-installer ``` 5. Verify the file against a documented cryptographic checksum or trusted signature. 6. Inspect the downloaded script before execution. 7. Run installation without `sudo` and under a minimally privileged account. ]]>
