T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:37
- Finding
- Unverified Remote Installation Script Executed Directly by a Shell<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md:37` **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: Critical ### Vulnerable Code ```bash curl -fsSL https://raw.githubusercontent.com/CaseMark/homebrew-casedev/main/install.sh | sh ``` ### Technical Analysis The installation instructions retrieve `install.sh` from the current state of a remotely controlled GitHub repository and immediately pipe its contents into `sh`. The script is not pinned to an immutable commit or versioned artifact, and the instructions provide no checksum or cryptographic signature verification. This design means that the code executed by a user or agent can change after the Skill package has been reviewed. Compromise of the repository, maintainer account, referenced branch, or upstream delivery mechanism could cause attacker-controlled commands to be returned and executed. The remote script is not included in this project, so its contents and behavior could not be audited. This finding concerns the unsafe execution mechanism and does not assert that the current remote script is itself malicious. ### Attack Path 1. An agent or user follows the installation instructions in `SKILL.md`. 2. `curl` requests the current contents of the remote `install.sh`. 3. An attacker who has compromised or gained control of the remote source changes the script to include malicious commands. 4. The response body is passed directly to `sh` without local inspection or integrity verification. 5. The malicious commands execute with the privileges of the account running the installation command. ### Impact Assessment Successful exploitation provides arbitrary shell-command execution under the invoking user's account. The resulting access could permit reading or modifying files available to that account, accessing environment variables and locally stored credentials, installing additional software, or downloading further payloads. If the command is run from a p ...[truncated 401 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the direct `curl | sh` installation command. 2. Prefer installation through a trusted package manager or a signed, versioned release artifact. 3. If a shell installer is unavoidable: - Pin the download URL to an immutable, reviewed release or commit. - Download the script to a local file instead of piping it directly into a shell. - Publish and verify a SHA-256 checksum or cryptographic signature. - Require inspection of the downloaded script before execution. - Execute it with the least-privileged account required for installation. 4. Document the files, directories, network destinations, and configuration changes made by the installer. 5. Avoid requesting administrative privileges unless a specific installation operation requires them. ]]>