T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:40
- Finding
- Unverified Remote Installer Is Piped Directly into Bash## Vulnerability Details **File Location**: `SKILL.md:40` **Vulnerability Type**: Remote payload retrieval and immediate execution **Risk Level**: High ### Vulnerable Code ```bash curl -sSfL https://raw.githubusercontent.com/Navneeth08k/semanticFS/main/scripts/install.sh | bash ``` ### Technical Analysis The documented installation command retrieves a shell script from the mutable `main` branch of a personal GitHub repository and immediately executes it with Bash. The artifact does not include the installer, so its behavior could not be audited as part of this review. No immutable commit or release version is selected, and the command performs no cryptographic hash or signature verification. Piping the response directly into Bash also prevents meaningful inspection before execution. Consequently, the effective installation payload can change after the Skill has been reviewed. Although installing the `semanticfs` executable supports the Skill's stated functionality, remote, unverified shell execution exceeds the minimum-risk method necessary to perform that installation. The installer receives all permissions held by the invoking user. ### Attack Path 1. An attacker compromises the referenced repository, its maintainer account, or another component of the content-delivery trust chain. 2. The attacker modifies `scripts/install.sh` on the mutable `main` branch. 3. A user or agent follows the prerequisite instructions in `SKILL.md`. 4. `curl` downloads the modified response from the external URL. 5. The shell pipeline passes the response directly to Bash without integrity verification or review. 6. The attacker's commands execute with the permissions of the invoking user and can retrieve additional payloads or interact with user-accessible system resources. ### Impact Assessment Successful exploitation permits arbitrary command execution with the invoking user's privileges. The payload could read or modify accessible ...[truncated 570 chars]
- Remediation
- ## Remediation Suggestions 1. Do not pipe network responses directly into a shell. Download the installer to a local file and require inspection before explicit execution. 2. Prefer distributing the executable through a trusted package manager or signed release mechanism. 3. Pin downloads to an immutable release artifact or commit rather than the mutable `main` branch. 4. Publish and verify a cryptographic digest or signature before running the installer. Store the expected digest in a separately authenticated, versioned location. 5. Include the installer in the audited Skill package when practical so its complete behavior can be reviewed. 6. Run installation with an unprivileged account and request elevated privileges only for narrowly defined operations that genuinely require them. 7. Use a hardened installation pattern such as: ```bash curl -fL -o install.sh "https://example.invalid/immutable-release/install.sh" echo "EXPECTED_SHA256 install.sh" | sha256sum -c - less install.sh bash install.sh ``` The placeholder URL and digest must be replaced with an immutable, authenticated release URL and its verified checksum.
