T03 · Remote Payload Retrieval and Execution
Error
- Location
- references/spm-build.md:300
- Finding
- Unverified Remote Installer Piped Directly to Bash## Vulnerability Details **File Location**: `references/spm-build.md:300-302` **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: Critical ### Vulnerable Code ```bash # Install swiftly curl -L https://swift.org/install | bash ``` ### Technical Analysis The installation instructions stream content retrieved from an external URL directly into Bash. The response is executed immediately without being saved for inspection, pinned to a specific immutable release, or validated using a cryptographic checksum or signature. HTTPS authenticates the connection under normal conditions, but it does not make mutable upstream content safe to execute. Compromise of the hosting infrastructure, DNS or redirect chain, certificate trust path, or upstream installer could cause arbitrary attacker-controlled commands to run. The `-L` option also follows redirects without constraining the final host. Executing a network response directly is not required for the Skill's declared Swift and macOS development functionality. A verifiable package or separately downloaded and authenticated installer would provide the same functionality with substantially lower privilege and supply-chain risk. ### Attack Path 1. An attacker compromises the installer host, its publishing process, or a destination in the HTTP redirect chain. 2. The attacker modifies the response returned by `https://swift.org/install` to contain malicious shell commands. 3. A user or AI Agent follows the Skill's documented installation command. 4. `curl -L` retrieves and follows redirects to the attacker-controlled content. 5. The pipe sends the response directly to Bash without integrity verification or review. 6. Bash executes the payload with the privileges and environment of the invoking user. ### Impact Assessment Successful exploitation provides arbitrary command execution under the invoking user's account. The payload could: - Read or modify files accessible to the user. - Access deve ...[truncated 569 chars]
- Remediation
- ## Remediation Suggestions 1. Remove the direct `curl | bash` pipeline. 2. Prefer an official, signed operating-system package or another installer whose authenticity is verified by the platform. 3. If a shell installer is unavoidable: - Pin an immutable release URL rather than a mutable installer endpoint. - Download the file separately. - Restrict or carefully validate redirects and the final destination. - Verify a cryptographic signature or a checksum obtained through an authenticated, independent channel. - Inspect the downloaded script before execution. - Execute only the verified local file. 4. Document the expected signer, checksum, release version, and verification commands. 5. Run the installer with the minimum necessary user privileges and avoid requesting administrative access unless explicitly required and justified. A safer documentation pattern is: ```bash curl --fail --show-error --location \ --output swiftly-install.sh \ "PINNED_IMMUTABLE_RELEASE_URL" # Verify the publisher's signature or authenticated checksum here. # Inspect the file before executing it. less swiftly-install.sh bash swiftly-install.sh ``` The placeholder verification step must be replaced with the official publisher's concrete signature or checksum procedure before this pattern is recommended to users.