SRCmail/vnc/plugins/smime/verify-fixes.mjs

// Standalone proof for the two VNC hardening fixes. Reimplements only the
// decision logic under test (no pkijs/DOM needed) so it runs with plain node.
//   node vnc/plugins/smime/verify-fixes.mjs
import { readFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';

const here = dirname(fileURLToPath(import.meta.url));
let pass = 0, fail = 0;
const check = (name, got, want) => {
  const ok = got === want;
  console.log(`${ok ? '  PASS' : '  FAIL'}  ${name}${ok ? '' : `  (got ${JSON.stringify(got)}, want ${JSON.stringify(want)})`}`);
  ok ? pass++ : fail++;
};

// ── Fix 1: auto-import gate ─────────────────────────────────────────
// Mirrors the guard order in index.js maybeAutoImportSigner.
function wouldImport(status, autoImport = true) {
  if (autoImport === false) return false;
  const cert = status && status.signerCert;
  if (!cert || !status.signatureValid || !cert.email) return false;
  if (status.signerEmailMatch !== true) return false;
  if (status.selfSigned) return false;
  return true;
}
const cert = { email: 'a@b.com', fingerprint: 'ff' };

console.log('\nFix 1 — certificate auto-import gate');
check('CA-signed, address matches -> import',
  wouldImport({ signerCert: cert, signatureValid: true, signerEmailMatch: true, selfSigned: false }), true);
check('THE ATTACK: self-signed, address matches -> REFUSE',
  wouldImport({ signerCert: cert, signatureValid: true, signerEmailMatch: true, selfSigned: true }), false);
check('address mismatch -> REFUSE',
  wouldImport({ signerCert: cert, signatureValid: true, signerEmailMatch: false, selfSigned: false }), false);
check('signerEmailMatch undefined (no From) -> REFUSE (fail closed)',
  wouldImport({ signerCert: cert, signatureValid: true, signerEmailMatch: undefined, selfSigned: false }), false);
check('invalid signature -> REFUSE',
  wouldImport({ signerCert: cert, signatureValid: false, signerEmailMatch: true, selfSigned: false }), false);
check('setting off -> REFUSE',
  wouldImport({ signerCert: cert, signatureValid: true, signerEmailMatch: true, selfSigned: false }, false), false);

// ── Fix 2 (finding 3): CRLF stripping ───────────────────────────────
function stripCrlf(value) {
  return String(value).replace(/[\r\n]+[ \t]*/g, ' ');
}
console.log('\nFinding 3 — CRLF header sanitisation');
check('BCC injection via display name',
  stripCrlf('Evil\r\nBcc: attacker@evil.com'), 'Evil Bcc: attacker@evil.com');
check('bare LF',   stripCrlf('a\nb'), 'a b');
check('bare CR',   stripCrlf('a\rb'), 'a b');
check('folded continuation collapsed', stripCrlf('a\r\n\tb'), 'a b');
check('multiple injected headers',
  stripCrlf('x\r\nBcc: a@b.c\r\nReply-To: d@e.f'), 'x Bcc: a@b.c Reply-To: d@e.f');
check('clean value untouched', stripCrlf('Normal Subject'), 'Normal Subject');
check('non-ASCII untouched', stripCrlf('Grüße büro'), 'Grüße büro');

// ── Finding 2: content-encryption allowlist ─────────────────────────
const ALLOW = new Map([
  ['2.16.840.1.101.3.4.1.2',  { name: 'AES-128-CBC', authenticated: false }],
  ['2.16.840.1.101.3.4.1.22', { name: 'AES-192-CBC', authenticated: false }],
  ['2.16.840.1.101.3.4.1.42', { name: 'AES-256-CBC', authenticated: false }],
  ['2.16.840.1.101.3.4.1.6',  { name: 'AES-128-GCM', authenticated: true }],
  ['2.16.840.1.101.3.4.1.26', { name: 'AES-192-GCM', authenticated: true }],
  ['2.16.840.1.101.3.4.1.46', { name: 'AES-256-GCM', authenticated: true }],
]);
const accepts = (oid) => ALLOW.has(oid);
const authed = (oid) => ALLOW.get(oid)?.authenticated ?? null;

console.log('\nFinding 2 — content-encryption allowlist');
check('AES-256-GCM accepted',           accepts('2.16.840.1.101.3.4.1.46'), true);
check('AES-256-GCM is authenticated',   authed('2.16.840.1.101.3.4.1.46'), true);
check('AES-128-CBC accepted (RFC 5751 interop)', accepts('2.16.840.1.101.3.4.1.2'), true);
check('AES-128-CBC NOT authenticated',  authed('2.16.840.1.101.3.4.1.2'), false);
check('3DES-CBC REFUSED',               accepts('1.2.840.113549.3.7'), false);
check('DES-CBC REFUSED',                accepts('1.3.14.3.2.7'), false);
check('RC2-CBC REFUSED',                accepts('1.2.840.113549.3.2'), false);
check('unknown OID REFUSED',            accepts('1.2.3.4.5'), false);

// HTML suppression decision (EFAIL mitigation)
const suppress = (contentAuthenticated, optOut = false) => !contentAuthenticated && !optOut;
check('GCM -> HTML rendered',                      suppress(true), false);
check('CBC -> HTML suppressed by default',         suppress(false), true);
check('CBC + explicit opt-out -> HTML rendered',   suppress(false, true), false);

// ── Finding 5: parser resource limits ───────────────────────────────
const MAX_DEPTH = 20, MAX_PARTS = 500;
// Mirrors the bounded recursion in parseEntity: past MAX_DEPTH a multipart is
// treated as a leaf; past MAX_PARTS siblings are dropped.
function walk(depth, budget) {
  if (depth >= MAX_DEPTH) return { depth, recursed: false };
  if (budget.parts >= MAX_PARTS) return { depth, recursed: false };
  budget.parts += 1;
  return walk(depth + 1, budget);
}
console.log('\nFinding 5 — parser resource limits');
check('recursion stops at MAX_DEPTH', walk(0, { parts: 0 }).depth, MAX_DEPTH);
check('part budget stops further recursion', walk(0, { parts: MAX_PARTS }).recursed, false);
check('deep-but-legal nesting still reaches the cap', walk(16, { parts: 0 }).depth, MAX_DEPTH);

// ── Source assertions: guard against silent regression ──────────────
console.log('\nSource assertions');
const idx = readFileSync(join(here, 'src/index.js'), 'utf8');
const mb = readFileSync(join(here, 'src/mime-builder.js'), 'utf8');
check('index.js checks signerEmailMatch !== true', idx.includes('status.signerEmailMatch !== true'), true);
check('index.js checks selfSigned', /if \(status\.selfSigned\)/.test(idx), true);
check('formatHeader sanitises its value', /function formatHeader\(name, rawValue\)[\s\S]{0,80}stripCrlf\(rawValue\)/.test(mb), true);
check('attachment Content-Type sanitised', mb.includes('stripCrlf(att.contentType)'), true);
check('Content-ID sanitised', mb.includes('stripCrlf(att.cid)'), true);
// Every header assembled outside formatHeader must use a literal or a sanitised value.
const bypass = [...mb.matchAll(/lines\.push\(`([A-Za-z-]+): ([^`]*)`\)/g)]
  .filter(([, , v]) => /\$\{/.test(v) && !/stripCrlf|encodeHeaderValue|boundary|altBoundary|disposition/.test(v));
check('no unsanitised interpolated headers remain', bypass.length, 0);
if (bypass.length) bypass.forEach(([m]) => console.log('      >>', m));

const dec = readFileSync(join(here, 'src/smime-decrypt.js'), 'utf8');
check('allowlist gate runs before any key use',
  dec.indexOf('checkContentEncryption(envelopedData)') < dec.indexOf('unlockedKeys.get'), true);
check('decrypt refuses non-allowlisted algorithms', /Refusing to decrypt/.test(dec), true);
check('no legacy CBC OID appears in the decrypt allowlist',
  /1\.2\.840\.113549\.3\.7|1\.3\.14\.3\.2\.7|1\.2\.840\.113549\.3\.2/.test(dec), false);
check('normal decrypt path uses the NATIVE engine',
  /if \(!useLiner\)[\s\S]{0,120}nativeEngine\(\)/.test(dec), true);
check('liner engine reachable only via useLiner',
  (dec.match(/getLinerCryptoEngine\(\)/g) || []).length, 1);
check('index.js suppresses HTML for unauthenticated content',
  idx.includes('suppressHtml') && idx.includes('result.contentAuthenticated'), true);

// finding 5
const mp = readFileSync(join(here, 'src/mime-parse.js'), 'utf8');
const det = readFileSync(join(here, 'src/smime-detect.js'), 'utf8');
check('mime-parse caps depth/parts/bytes',
  /MAX_DEPTH/.test(mp) && /MAX_PARTS/.test(mp) && /MAX_BYTES/.test(mp), true);
check('parseEntity threads depth + budget',
  /function parseEntity\(raw, depth = 0, budget/.test(mp), true);
check('parseEntity guards on depth before recursing',
  /params\.boundary && depth < MAX_DEPTH/.test(mp), true);
check('no unbounded .map(parseEntity) left', /\.map\(parseEntity\)/.test(mp), false);
check('both bodyStructure walkers are depth-capped',
  (det.match(/depth < MAX_WALK_DEPTH/g) || []).length, 2);

// finding 4 hardening
check('lockOnLogout opt-out removed from wipe paths',
  /settings\(\)\.lockOnLogout === false\) return/.test(idx), false);
check('exit wipe registered (pagehide + beforeunload)',
  idx.includes("addEventListener('pagehide'") && idx.includes("addEventListener('beforeunload'"), true);
check('boot wipe still present', /clearSessionKeys\(\)/.test(idx), true);
const mani = JSON.parse(readFileSync(join(here, 'manifest.json'), 'utf8'));
check('dead lockOnLogout setting removed from manifest',
  'lockOnLogout' in mani.settingsSchema, false);
check('auth:observe still declared (B-09 safety)',
  mani.permissions.includes('auth:observe'), true);

console.log(`\n${fail === 0 ? 'ALL PASS' : 'FAILURES'} — ${pass} passed, ${fail} failed\n`);
process.exit(fail === 0 ? 0 : 1);