T08 · Insecure Dependencies
- Location
SKILL.md:238- Finding
Unpinned Executable Installed from a Third-Party Homebrew Tap
- Content
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Vulnerability Details
File Location:
SKILL.md, line 238; repeated at lines 249, 334, and 357
Vulnerability Type: Unverified third-party dependency
Risk Level: Mediumbash brew install odysseus0/tap/feedTechnical Analysis
The Skill instructs users or agents to install the required
feedexecutable from a third-party Homebrew tap without pinning an exact version, commit, or artifact checksum. The documentation also does not identify a reviewed source repository or require verification of the downloaded package.Because the external formula and its referenced artifacts can change after the Skill has been audited, the code ultimately executed by subsequent
feed fetch,feed get, andfeed updatecommands is not bounded to a reviewed version. A compromise of the tap, its maintainer account, the formula's upstream download location, or the release artifact could introduce attacker-controlled code.Network access is necessary for the declared RSS-fetching functionality, and the reviewed Skill does not explicitly transmit credentials or private files. The risk instead arises from executing a mutable, externally supplied dependency with the permissions of the user or agent.
Attack Path
- An attacker compromises the third-party Homebrew tap, its maintainer account, or an upstream artifact referenced by its formula.
- The attacker publishes a modified formula or malicious
feedrelease under the expected package name. - A user or agent follows the Skill's documented
brew install odysseus0/tap/feedinstruction. - Homebrew downloads and installs the altered dependency without the Skill verifying an expected version or checksum.
- The Skill invokes the installed binary through commands such as
feed fetch. - The malicious binary executes with the invoking account's permissions and can abuse any filesystem, process, environment, or network access available in that execution context.
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- Remediation
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Remediation Suggestions
- Pin the dependency to a reviewed immutable version or commit rather than installing the current package from a mutable tap.
- Publish the expected SHA-256 checksum for the release artifact and verify it before installation or execution.
- Document the canonical source repository, release URL, maintainer identity, and reviewed version.
- Prefer an official package source with signed releases and provenance attestations. If the third-party tap remains necessary, pin the tap repository to a reviewed commit.
- Build from a pinned source revision in a controlled environment where practical, and verify reproducible build outputs.
- Run the CLI in a restricted sandbox with access only to its feed database and required configuration files.
- Limit outbound network access to explicitly configured HTTP or HTTPS feed hosts and deny loopback, private-network, link-local, and cloud-metadata destinations unless they are specifically required.
- Avoid exposing unrelated secrets or sensitive environment variables to the CLI process.
- Add dependency integrity checks and periodic source review to the Skill's installation workflow.