T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:26
- Finding
- Unverified Remote Installer Is Piped Directly into a Shell<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md`, line 26 **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: Critical ### Vulnerable Code ```bash curl -fsSL https://kubevpn.dev/install.sh | sh # Linux/macOS ``` ### Technical Analysis The installation instructions download a mutable script from an external endpoint and immediately execute it with `sh`. The user has no opportunity to inspect the retrieved content, and the command performs no version pinning, checksum validation, or cryptographic signature verification. HTTPS protects the network connection in transit but does not guarantee that the server, hosting account, DNS infrastructure, or published script has not been compromised. Because the effective payload can change after this Skill has been reviewed, the command creates a direct remote code-execution channel. The installation source may be associated with the documented KubeVPN project, but the repository contains no checksum, signature, pinned artifact, or local copy that would allow the executed payload to be independently verified. ### Attack Path 1. An attacker compromises the `kubevpn.dev` hosting endpoint, its deployment pipeline, DNS, or another component capable of changing `install.sh`. 2. The attacker replaces or modifies the script with malicious shell commands. 3. A user or agent follows the documented installation command. 4. `curl` retrieves the attacker-controlled response. 5. The shell executes the response immediately without integrity verification or review. 6. The payload performs arbitrary actions using the privileges of the invoking account. If the installer obtains or is run with elevated privileges, the compromise may extend to the entire host. ### Impact Assessment Successful exploitation permits arbitrary command execution as the user running the command. Potential consequences include credential theft, modification of user files, installation of malicious binaries, per ...[truncated 369 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the direct `curl | sh` installation pattern. 2. Direct users to a version-pinned release artifact from the project's documented official release channel. 3. Download the artifact separately so it can be reviewed before execution. 4. Publish and require verification of a SHA-256 checksum or, preferably, a cryptographic signature whose verification key is distributed through a separate trusted channel. 5. Use a workflow similar to: ```bash curl -fL -o kubevpn.tar.gz https://example.invalid/releases/download/vX.Y.Z/kubevpn.tar.gz echo "<EXPECTED_SHA256> kubevpn.tar.gz" | sha256sum --check - ``` 6. Extract and install only after successful verification. 7. Prefer package managers that support signed, versioned packages. 8. Document whether installation requires elevated privileges and ensure elevation is limited to the exact filesystem operation that needs it. ]]>