T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:18
- Finding
- Mutable Remote Installer Is Executed Directly Through Bash## Vulnerability Details **File Location**: `SKILL.md`, line 18 **Vulnerability Type**: Remote payload retrieval and immediate shell execution **Risk Level**: High **Vulnerable Code**: ```bash bun --version || curl -fsSL https://bun.sh/install | bash ``` ### Technical Analysis When Bun is unavailable, the command downloads the current response from `https://bun.sh/install` and immediately passes it to Bash. The remote script is neither version-pinned nor authenticated through a checksum or cryptographic signature. It is also not saved for inspection before execution. Consequently, the code that ultimately runs can change after the Skill has been reviewed. Compromise of the remote service, its deployment pipeline, or the applicable DNS/TLS trust path could cause arbitrary shell commands to be returned and executed. Bun may be needed by the subsequent build operation, but executing a mutable remote response through `curl | bash` is not the minimum privilege or minimum-risk installation mechanism necessary for the Skill's documentation-querying purpose. ### Attack Path 1. Bun is absent from the user's environment. 2. The user or agent follows the setup instructions in `SKILL.md`. 3. The shell evaluates the fallback after `bun --version` fails. 4. `curl` retrieves a mutable script from the external endpoint. 5. The response is streamed directly into Bash without integrity verification or review. 6. A malicious or compromised response executes arbitrary commands with the permissions of the invoking user. ### Impact Assessment A malicious response can obtain the invoking user's privileges and access files, environment variables, credentials, and network resources available to that account. It could modify shell configuration, install additional software, or establish persistence, although the reviewed Skill does not itself explicitly instruct the installer to perform those actions. If Context7 credentials are already ...[truncated 261 chars]
- Remediation
- ## Remediation Suggestions - Remove the `curl | bash` installation instruction. - Declare Bun as an explicit prerequisite and direct users to an approved package manager or official manual installation process. - Pin Bun to a reviewed version. - Download the installer or release artifact separately, verify its published cryptographic signature or SHA-256 checksum, and only then execute or install it. - Avoid automatic installation during Skill execution; require explicit user approval before changing the local development environment. - Run installation with ordinary user privileges and do not request `sudo` or administrator access.
