34 lines
2.4 KiB
Org Mode
34 lines
2.4 KiB
Org Mode
#+TITLE: Root Cause Analysis: Shell Actuator Security Hardening
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#+DATE: 2026-04-11
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#+FILETAGS: :rca:security:shell:injection:autonomy:
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* Executive Summary
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During the formal verification of the `org-skill-shell-actuator`, a critical command injection vulnerability was identified and patched. The previous implementation relied on a naive whitelist check that could be bypassed using shell metacharacters.
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* 1. Issue: Command Injection Vulnerability
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** Symptoms
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Commands like `ls ; rm -rf /` were potentially executable if the first word (`ls`) was in the whitelist.
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** Root Cause
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The `execute-shell-safely` function only checked the first space-delimited word of the command string against the `*allowed-commands*` whitelist. Since `uiop:run-program` executes string-based commands via `/bin/sh -c`, the shell would process the entire string, including injected commands following metacharacters like `;`, `&`, or `|`.
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** Resolution
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1. **Metacharacter Blacklist:** Introduced `*shell-metacharacters*` containing dangerous shell symbols (`; & | > < $ \` \ !`).
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2. **Strict Validation:** Updated `execute-shell-safely` to scan the *entire* command string for these characters before performing the whitelist check.
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3. **Defense-in-Depth:** Any command containing a metacharacter is now rejected with a "Security Violation" error, even if the primary command is whitelisted.
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* 2. Side-Issue: Missing Package Context
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** Symptoms
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`UNDEFINED-FUNCTION EXECUTE-SHELL-SAFELY` during unit tests.
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** Root Cause
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`src/shell-logic.lisp` was missing an `(in-package :opencortex)` declaration, causing symbols to be defined in the default `COMMON-LISP-USER` package instead of the harness package.
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** Resolution
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Added the `in-package` header to `shell-logic.lisp`.
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* 3. opencortex Mandate Alignment
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** Invariant Check
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- *High-Integrity Memory:* The shell actuator is now formally verified with 4 new unit tests covering whitelist enforcement and injection blocking.
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- *Literate Programming:* Updated `org-skill-shell-actuator.org` Phase A and Build sections to reflect the hardened logic.
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* 4. Permanent Learnings
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- **Whole-String Validation:** Never assume that whitelisting the "head" of a command string is sufficient when passing that string to a shell.
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- **Subshell Avoidance:** While the current fix blacklists metacharacters, future iterations should move toward passing command arguments as a Lisp list to `uiop:run-program`, bypassing the shell entirely.
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