T08 · Insecure Dependencies
Warning
- Location
- SKILL.md:34
- Finding
- Unpinned Third-Party Package Execution Through npx## Vulnerability Details **File Location**: `SKILL.md:34-37` **Vulnerability Type**: Unpinned and mutable third-party dependency execution **Risk Level**: Medium ```markdown ## Connect once ``` npx skills add powmcp/skills --skill preflight-client-endpoint-before-integration ``` ``` ### Technical Analysis The installation instructions invoke the third-party `skills` package through `npx` without specifying an exact package version or integrity digest. If the package is not already available locally, `npx` can retrieve and execute its currently published version. The `powmcp/skills` source is likewise referenced without an immutable commit identifier or reviewed release version. Consequently, the code executed during installation can change after this Skill has been reviewed. Compromise of the npm package, its publisher account, or the referenced Skill repository could introduce malicious installation behavior through a later release. This is a supply-chain risk rather than evidence that the currently referenced package is malicious. ### Attack Path 1. An attacker compromises the npm package, its publishing credentials, or the mutable `powmcp/skills` source. 2. The attacker publishes a modified package or repository revision containing malicious installation logic. 3. A user follows the documented `npx skills add ...` command. 4. `npx` resolves and downloads the mutable package version, while the installer resolves the mutable Skill source. 5. Attacker-controlled code executes in the user's environment during installation or subsequent Skill loading. 6. The payload operates with the permissions of the user who ran the command. ### Impact Assessment Successful exploitation could allow arbitrary code execution with the installing user's privileges. Depending on that user's access and the behavior of the compromised package, the payload could read or alter accessible files, environment variables ...[truncated 251 chars]
- Remediation
- ## Remediation Suggestions 1. Pin the `skills` CLI to a reviewed exact version, for example by using an explicit package version rather than allowing `npx` to resolve the latest release. 2. Pin `powmcp/skills` to an immutable commit hash, signed tag, or versioned release supported by the installer. 3. Use a lockfile and verify package integrity hashes where the installation workflow supports them. 4. Disable automatic acceptance of newly published versions and require security review before updating either dependency. 5. Prefer a trusted, preinstalled CLI in controlled environments instead of downloading executable package content at invocation time. 6. Run installation with the minimum required user privileges and without unnecessary credentials or sensitive environment variables. 7. Document the expected package version, source revision, and checksum so users can verify the reviewed artifact before execution.