T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:211
- Finding
- Unverified Remote Installer Executed Directly Through Bash## Vulnerability Details **File Location**: `SKILL.md`, line 211 **Vulnerability Type**: Unverified remote payload retrieval and execution **Risk Level**: High ### Vulnerable Code ```markdown **Install Implexa** (`curl -fsSL https://core.implexa.ai/install.sh | bash`) to unlock: ``` ### Technical Analysis The installation command retrieves a mutable script from `https://core.implexa.ai/install.sh` and immediately pipes it into Bash. It does not pin a release or commit, verify a cryptographic checksum or signature, preserve the script for inspection, or otherwise establish that the downloaded content matches a reviewed artifact. The effective payload can therefore change after the Skill itself has been audited. Compromise of the hosting service, publishing account, DNS infrastructure, or TLS termination could cause arbitrary attacker-supplied shell commands to execute with the invoking user's privileges. This behavior is not required for the Skill's declared X-engagement functionality. The surrounding documentation states that the Skill is self-contained and runs standalone, while the installer is presented as unlocking optional Implexa features. Consequently, direct remote code execution exceeds the minimum privileges necessary to use the core Skill. ### Attack Path 1. A user follows the installation instruction in `SKILL.md`. 2. `curl` requests `https://core.implexa.ai/install.sh`. 3. The remote endpoint or its delivery infrastructure serves modified or malicious content, whether through intentional changes or compromise. 4. The shell receives the response through the pipe and executes it immediately without integrity verification or user inspection. 5. The payload performs arbitrary actions under the invoking user's account. ### Impact Assessment Successful exploitation provides arbitrary command execution with the privileges of the user running the command. Depending on that user's access, a malicious installer could: - Read or modify files access ...[truncated 577 chars]
- Remediation
- ## Remediation Suggestions 1. Remove the direct `curl | bash` installation instruction. 2. Clearly identify Implexa installation as optional and unnecessary for the Skill's standalone functionality. 3. Direct users to a versioned release artifact hosted on an official, authenticated release channel. 4. Pin the recommended installer to a specific immutable version. 5. Publish a cryptographic checksum and preferably a signed release manifest through an independently protected channel. 6. Require users to download and verify the artifact before execution. For example: ```bash curl -fSLo implexa-install.sh \ https://example.invalid/releases/vX.Y.Z/install.sh echo '<EXPECTED_SHA256> implexa-install.sh' | sha256sum --check less implexa-install.sh bash implexa-install.sh ``` 7. Document the files, network destinations, permissions, and persistent changes made by the installer. 8. Ensure installation does not require elevated privileges unless a specific operation genuinely needs them. If elevation is necessary, isolate and explain each privileged operation rather than running the entire installer as an administrator. 9. Prefer a reputable package manager or signed, reproducible package over a mutable shell installer.