T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:36
- Finding
- Mutable Remote Installation Script Is Downloaded and Executed Without Verification<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md`, line 36 **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: Critical ```bash curl -sSL https://raw.githubusercontent.com/dwirx/duckse/main/scripts/install.sh | bash ``` ### Technical Analysis The installation instructions retrieve a shell script from the mutable `main` branch of a personal GitHub repository and pipe the response directly into Bash. The downloaded content is neither pinned to an immutable release or commit nor authenticated through a cryptographic signature or checksum. This pattern creates a remote code-execution channel whose effective payload can change after the Skill has been audited. It also prevents meaningful review before execution. Compromise of the repository owner’s account, repository, upstream delivery path, or installation script would allow an attacker to substitute arbitrary shell commands. Installing a search utility supports the Skill’s declared functionality, but executing an unverified, mutable remote script is not necessary and exceeds the minimum authority required for installation. The project contains no local copy of the installer, so its behavior and security properties cannot be bounded by this audit. ### Attack Path 1. An attacker compromises the external repository, its maintainer account, or another component capable of modifying the referenced installer. 2. The attacker changes `scripts/install.sh` on the `main` branch to include malicious shell commands. 3. A user or Agent follows the Skill’s prerequisite instructions because `duckse` is unavailable. 4. `curl` downloads the modified script without pinning or integrity verification. 5. The shell immediately executes the response with the privileges of the invoking account. 6. The payload can access resources available to that account and may install further malicious components. ### Impact Assessment Successful exploitation provides arbitrary command execution wit ...[truncated 786 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the direct `curl | bash` installation command. 2. Prefer a trusted package registry or a versioned release artifact with transparent package metadata. 3. Pin downloads to an immutable release or commit rather than the mutable `main` branch. 4. Publish and verify a SHA-256 checksum or cryptographic signature before execution. 5. Download the installer to a local file, inspect it, and require explicit user approval before running it. For example: ```bash curl -fL -o install.sh "https://example.invalid/duckse/releases/download/vX.Y.Z/install.sh" echo "<EXPECTED_SHA256> install.sh" | sha256sum --check - less install.sh bash install.sh ``` 6. Document the installer’s filesystem and network actions and ensure it operates without administrative privileges. 7. Prefer reproducible manual installation steps or package-manager commands that install only the files required for the search CLI. 8. Advise users never to run the installer with `sudo` unless a narrowly defined, independently reviewed operation genuinely requires elevation. ]]>