T01 · Skill Instruction Hijacking
Error
- Location
- SKILL.md:614
- Finding
- Mutable Remote Skill Content Is Treated as Runtime Execution Authority<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md:614-620` **Vulnerability Type**: Remote instruction replacement and execution **Risk Level**: Critical ### Vulnerable Code ```markdown Always **refresh** the full skill bundle at the start of every heartbeat — the latest published version at <https://openjobs.bot/heartbeat.md> and <https://openjobs.bot/skill.md> are the **runtime execution authority**: ```bash # Re-install the full skill bundle (updates HEARTBEAT.md, SKILL.md, references/): openjobs install-skill --agent <your-runtime> --force ``` ``` ### Technical Analysis The Skill explicitly instructs the Agent to overwrite the locally reviewed Skill bundle at the beginning of every heartbeat. It also declares the latest remotely published documents to be the authoritative runtime instructions. This creates a mutable execution channel outside the audited project. The effective instructions executed by the Agent can change after review without a local code change, integrity verification, version pin, diff review, or renewed operator approval. The `--force` option increases the risk by permitting replacement of the existing reviewed files. This behavior exceeds the minimum privileges needed to interact with the OpenJobs marketplace. Marketplace operations do not require remotely hosted instructions to replace the local Skill before every run. ### Attack Path 1. An attacker compromises `openjobs.bot`, its deployment pipeline, the CLI publisher account, or another component involved in distributing the Skill bundle. 2. The attacker modifies the remotely distributed `SKILL.md`, `HEARTBEAT.md`, or associated references. 3. A scheduled or manually triggered heartbeat runs the mandatory refresh command with `--force`. 4. The reviewed local Skill is replaced with attacker-controlled instructions. 5. The Agent loads the new content as “runtime execution authority.” 6. The malicious instructions can direct the Agent to invoke tools, disclose file ...[truncated 901 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the requirement to refresh the Skill automatically before every heartbeat. 2. Do not designate remote documents as runtime execution authority. 3. Pin the Skill and CLI to an explicitly reviewed version. 4. Verify downloaded content using an allowlisted cryptographic digest or signed release metadata. 5. Download proposed updates into a staging directory rather than overwriting active Skill files. 6. Display a version comparison and complete diff before installation. 7. Require explicit operator approval before activating updated instructions. 8. Re-audit updated scripts and instructions before execution. 9. Avoid `--force` in automated workflows. 10. Retain a verified rollback copy of the previously approved Skill. ]]>
