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fix(av-surface): no runnable base64-to-shell line on disk

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PLAN § v8.1.3 tillegg a. The bash-evasion gallery's T8 comment held a
complete base64-decode-into-shell line whose 16-char blob decodes to a
home-directory deletion, under probe (b)'s 24-char floor. Probe (b2)
found two more of the same shape, fixed here too: the gallery README's
T8 row and tests/e2e/attack-chain.test.mjs (an /etc deletion). Chosen
over an exception list because the gate should have none.

The gallery and the e2e test now encode the blob at runtime from the
same fragments; the README shows a placeholder. Gallery: 10/10 blocked.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Kjell Tore Guttormsen 2026-09-23 11:35:50 +02:00
commit 58d2e8ad8d
Signed by: ktg
SSH key fingerprint: SHA256:JakMjO6FTBBzN0Bhfj9saOoEjaFxlSdYuZQQpM/lF9Q
4 changed files with 12 additions and 8 deletions
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3
tests/e2e/attack-chain.test.mjs
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@ -130,7 +130,8 @@ describe('e2e attack-chain — Stage 2: destructive Bash with evasion', () => {
it('blocks T8 base64-pipe-shell (echo … | base64 -d | bash)', async () => {
const result = await runHook(BASH_GUARD, {
tool_name: 'Bash',
tool_input: { command: 'echo cm0gLXJmIC9ldGM= | base64 -d | bash' },
// Blob encoded at runtime: no runnable base64-to-shell line on disk (v8.1.3).
tool_input: { command: `echo ${Buffer.from('rm -rf /etc').toString('base64')} | base64 -d | bash` },
});
assert.equal(result.code, 2);
assert.match(result.stderr, /base64/i);