T03 · Remote Payload Retrieval and Execution
- Location
SKILL.md:57- Finding
Unverified Third-Party Binary Download and System-Wide Installation
- Content
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Vulnerability Details
File Location:
SKILL.md, lines 57-61
Vulnerability Type: Remote executable retrieval without a pinned checksum, followed by privileged installation
Risk Level: HighVulnerable code:
bash curl -LO https://github.com/wangwalk/inotes/releases/download/v0.1.2/inotes-0.1.2-universal-apple-darwin.tar.gz # Verify checksum from release notes tar xzf inotes-0.1.2-universal-apple-darwin.tar.gz sudo cp inotes /usr/local/bin/ sudo chmod +x /usr/local/bin/inotesTechnical Analysis
The skill instructs the user to retrieve a precompiled executable from a third-party GitHub repository, extract it, and place it in a system-wide executable directory. Although the URL specifies release version
v0.1.2and uses HTTPS, the instructions do not provide an expected SHA-256 digest or an executable command that enforces integrity verification.The comment
# Verify checksum from release notesis not an effective security control. It neither supplies a trusted digest nor causes installation to fail if verification is omitted or unsuccessful. A user or agent following the commands literally can therefore install the binary without authenticating its contents.The use of
sudogives the installation commands administrative write access to/usr/local/bin. This is broader than the minimum access necessary to run a per-user Notes utility; installation into a user-controlled directory such as~/.local/binwould avoid administrative filesystem modification. The downloaded binary is not shown being executed with root privileges, so this does not by itself prove root code execution. Nevertheless, privileged placement makes the unverified executable available system-wide and could overwrite an existinginotesexecutable.The document asserts that the installation is auditable and comes from a signed release, but the provided workflow performs no signature verification. The repository contains only d ...[truncated 2060 chars]
- Remediation
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Remediation Suggestions
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Publish the exact SHA-256 digest in
SKILL.mdand enforce it before extraction:bash curl --fail --location --proto '=https' --tlsv1.2 \ --output inotes-0.1.2-universal-apple-darwin.tar.gz \ https://github.com/wangwalk/inotes/releases/download/v0.1.2/inotes-0.1.2-universal-apple-darwin.tar.gz printf '%s %s\n' \ 'EXPECTED_SHA256_DIGEST' \ 'inotes-0.1.2-universal-apple-darwin.tar.gz' | shasum -a 256 -c -Installation must stop if verification fails.
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Prefer a cryptographically signed release and verify its signature against a maintainer key whose fingerprint is distributed through a separate trusted channel. Do not describe the release as signed unless the workflow actually validates that signature.
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Build from a pinned, reviewed source commit where feasible. Document the relationship between the source commit, release tag, and generated binary.
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Avoid administrative installation by default:
bash install -d "$HOME/.local/bin" install -m 0755 inotes "$HOME/.local/bin/inotes"Explain how to add that directory to
PATH. Offer/usr/local/bininstallation only as an explicit system-wide alternative. -
Before replacing an existing executable, check its location and require informed confirmation. Do not silently overwrite
/usr/local/bin/inotes. -
Extract into a newly created private temporary directory, inspect the archive listing first, and reject absolute paths, parent-directory traversal entries, symlinks, or unexpected files.
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Pin the Homebrew formula to an audited release and ensure the formula contains the release artifact's immutable SHA-256 digest. Users should be told how to inspect the personal tap and formula before installation.
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Correct the security documentation so that “local-only,” “no network calls,” and similar guarantees are clearly scoped to a specifically verified build rather than any execu ...[truncated 39 chars]
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