DC-079 2-round GLM-5.3 judge verdict: round1=C (blocking path-traversal
in assets/themes) → round2=A. 20/20 tests in routes/discover-disaster
(8 original + 12 new). Full repo: 2351/2351 (4 pre-existing billing
pdfkit failures unchanged).
THREAT MODEL
POST /api/v1/disaster/restore was the ONLY endpoint in the route tree
that wrote directly to process.env.CADDYFILE_PATH (=/caddyfile in
container = /etc/caddy/Caddyfile on host via start.sh:161 bind-mount).
Pre-fix: an authenticated dashboard operator POSTed
{caddyfile: '<attacker-controlled-string>'}
and the handler called fsp.writeFile(caddyfilePath, snapshot.caddyfile),
overwriting the live Caddyfile immediately. Caddy reads this file on
every reload (ACME renewal, health probe, admin API touch), so the
attacker-controlled content executes as Caddy config directives:
- import /etc/caddy/<anything-caddy-can-read> (content theft)
- admin off (lock out admin API)
- reverse_proxy to attacker IPs (Caddy becomes a pivot)
- acme_ca override to attacker CA (rogue cert issuance)
- log to attacker-writable paths (DoS/escape)
This bypassed the CLAUDE.md hard rule 'Caddyfile edits must use
caddy-apply' (validates + reloads + git-commits atomically).
FIX 1 — Caddyfile staging (round-1)
- New validateCaddyfileContent(): type check, non-empty check,
512 KiB byte cap (defense-in-depth below the 1 MB body-parser limit),
FORBIDDEN_IMPORT_RE rejects directives with absolute paths,
../-escape, ~/, or URL-encoded payloads.
- POST /disaster/restore now writes to <dataDir>/disaster-staged/
Caddyfile.candidate (atomic write + rename), NEVER to caddyfilePath.
- Response includes caddyfileStaged[{file, stagedPath, action: 'awaiting
caddy-apply', livePath}] and a DC-079 warning instructing the operator
to run `caddy-apply <reason>` to validate + reload + git-commit.
FIX 2 — assets/themes path-traversal (round-2 BLOCKING)
GLM round-1 caught a parallel vector: snapshot.assets[name] and
snapshot.themes[name] are user-controlled JSON keys flowing into
path.join(assetsDir, name) and path.join(themesDir, name). An attacker
could POST {assets: {'../../etc/caddy/Caddyfile': '<base64-evil>'}}
and overwrite the live Caddyfile via the dataDir bind-mount, fully
bypassing Fix 1.
- ASSET_KEY_RE = /^[a-zA-Z0-9._-]+$/ + ASSET_PATH_TRAVERSAL_RE catch
slashes, leading '..', and absolute-path keys.
- THEME_NAME_RE = /^[a-zA-Z0-9._-]+\.json\$/ additionally forces
.json extension and no slashes.
- assertSafeAssetKey/assertSafeThemeName helpers throw on invalid input.
- Both restore loops now: assert → path.resolve(dir, name) → containment
check (resolved must start with path.resolve(dir) + path.sep) → write
to resolved (never the raw join).
TESTS
12 new tests in __tests__/routes/discover-disaster.routes.test.js:
- staging: live sentinel unchanged, candidate at expected path
- rejects: non-string, empty, oversize, 3 forbidden-import variants
- assets: path-traversal key, absolute-path key
- themes: path-traversal name, no-extension name
- back-compat: no caddyfile field succeeds without staging
dashcaddy-polish