Four gaps in DANGEROUS_PATTERNS found by running 10 targeted tests that
each mapped to a specific pattern in approval.py and checked whether the
documented defense actually held.
1. **Heredoc script injection** — `python3 << 'EOF'` bypasses the
existing `-e`/`-c` flag pattern. Adds pattern for interpreter + `<<`
covering python{2,3}, perl, ruby, node.
2. **PID expansion self-termination** — `kill -9 $(pgrep hermes)` is
opaque to the existing `pkill|killall` + name pattern because command
substitution is not expanded at detection time. Adds structural
patterns matching `kill` + `$(pgrep` and backtick variants.
3. **Git destructive operations** — `git reset --hard`, `push --force`,
`push -f`, `clean -f*`, and `branch -D` were entirely absent.
Note: `branch -d` also triggers because IGNORECASE is global —
acceptable since -d is still a delete, just a safe one, and the
prompt is only a confirmation, not a hard block.
4. **chmod +x then execute** — two-step social engineering where a
script containing dangerous commands is first written to disk (not
checked by write_file), then made executable and run as `./script`.
Pattern catches `chmod +x ... [;&|]+ ./` combos. Does not solve the
deeper architectural issue (write_file not checking content) — that
is called out in the PR description as a known limitation.
Tests: 23 new cases across 4 test classes, all in test_approval.py:
- TestHeredocScriptExecution (7 cases, incl. regressions for -c)
- TestPgrepKillExpansion (5 cases, incl. safe kill PID negative)
- TestGitDestructiveOps (8 cases, incl. safe git status/push negatives)
- TestChmodExecuteCombo (3 cases, incl. safe chmod-only negative)
Full suite: 146 passed, 0 failed.
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