T03 · Remote Payload Retrieval and Execution
Error
- Location
- SKILL.md:62
- Finding
- Unverified Remote Installer Executed Directly by a Shell## Vulnerability Details **File Location**: `SKILL.md`, lines 62 and 99 **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: Critical **Vulnerable code at line 62:** ```bash curl -fsSL https://tailscale.com/install.sh | sh ``` **Vulnerable code at line 99:** ```bash curl -fsSL https://tailscale.com/install.sh | sh ``` ### Technical Analysis The Skill instructs users to retrieve a mutable installation script from an external URL and stream it directly into `sh`. The downloaded content is not pinned to a specific version, saved for inspection, or validated using a cryptographic signature or checksum. HTTPS protects the connection in transit under normal conditions, and the URL appears to use Tailscale's official domain. However, it does not establish that the returned script is immutable or independently verified. The effective code can change after the Skill has been reviewed. Compromise of the remote hosting infrastructure, domain, TLS trust chain, or installer publication process could therefore turn these instructions into an arbitrary code-execution channel. Installing Tailscale is relevant to the declared functionality, but executing an unverified remote script immediately is not the least-risk installation method. The installer may invoke privileged package-management operations or ask the user for authorization, potentially modifying repositories, packages, services, firewall settings, and network configuration. ### Attack Path 1. The user or AI agent follows either the residential-node or cloud-node setup instructions. 2. `curl` requests the current contents of `https://tailscale.com/install.sh`. 3. An attacker who has compromised the publication infrastructure, domain, delivery path, or installer supplies modified shell code. 4. The pipeline passes the response directly to `sh` without inspection or integrity verification. 5. The malicious commands execute with the invoking user' ...[truncated 978 chars]
- Remediation
- ## Remediation Suggestions - Remove both direct `curl | sh` pipelines. - Prefer installation through an authenticated operating-system package repository using the platform's native package manager. - Pin the package or installer to an explicitly reviewed version where operationally feasible. - If a standalone installer must be used, download it to disk first, verify a vendor-published cryptographic signature or checksum obtained through a trusted channel, inspect it, and execute it only after verification succeeds. - Require explicit human confirmation before installation, privilege elevation, service activation, firewall changes, or system-wide route changes. - Document which packages, repositories, services, firewall rules, and networking settings the installation is expected to modify. - Separate download, verification, and execution into distinct commands so that retrieval failure or verification failure cannot proceed to execution. - Apply the safer installation procedure consistently to both the residential node and the cloud node.