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MeshCentral/authenticode.js

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/**
* @description Authenticode parsing
* @author Ylian Saint-Hilaire & Bryan Roe
* @copyright Intel Corporation 2018-2022
* @license Apache-2.0
* @version v0.0.1
*/
/*jslint node: true */
/*jshint node: true */
/*jshint strict:false */
/*jshint -W097 */
/*jshint esversion: 6 */
"use strict";
const fs = require('fs');
const crypto = require('crypto');
const forge = require('node-forge');
const pki = forge.pki;
const p7 = require('./pkcs7-modified');
// Generate a test self-signed certificate with code signing extension
function createSelfSignedCert(args) {
var keys = pki.rsa.generateKeyPair(2048);
var cert = pki.createCertificate();
cert.publicKey = keys.publicKey;
cert.serialNumber = (typeof args.serial == 'string')?args.serial:'012345'; // Serial number must always have a single leading '0', otherwise toPEM/fromPEM will not work right.
cert.validity.notBefore = new Date();
cert.validity.notAfter = new Date();
cert.validity.notAfter.setFullYear(cert.validity.notBefore.getFullYear() + 10);
var attrs = [];
if (typeof args.cn == 'string') { attrs.push({ name: 'commonName', value: args.cn }); }
if (typeof args.country == 'string') { attrs.push({ name: 'countryName', value: args.country }); }
if (typeof args.state == 'string') { attrs.push({ name: 'ST', value: args.state }); }
if (typeof args.locality == 'string') { attrs.push({ name: 'localityName', value: args.locality }); }
if (typeof args.org == 'string') { attrs.push({ name: 'organizationName', value: args.org }); }
if (typeof args.orgunit == 'string') { attrs.push({ name: 'OU', value: args.orgunit }); }
cert.setSubject(attrs);
cert.setIssuer(attrs);
cert.setExtensions([{ name: 'basicConstraints', cA: false }, { name: 'keyUsage', keyCertSign: false, digitalSignature: true, nonRepudiation: false, keyEncipherment: false, dataEncipherment: false }, { name: 'extKeyUsage', codeSigning: true }, { name: "subjectKeyIdentifier" }]);
cert.sign(keys.privateKey, forge.md.sha384.create());
return { cert: cert, key: keys.privateKey, extraCerts: [] };
}
// Create the output filename if not already specified
function createOutFile(args, filename) {
if (typeof args.out == 'string') return;
var outputFileName = filename.split('.');
outputFileName[outputFileName.length - 2] += '-out';
args.out = outputFileName.join('.');
}
// Load certificates and private key from PEM files
function loadCertificates(pemFileNames) {
var certs = [], keys = [];
if (pemFileNames == null) return;
if (typeof pemFileNames == 'string') { pemFileNames = [pemFileNames]; }
for (var i in pemFileNames) {
try {
// Read certificate
var pem = fs.readFileSync(pemFileNames[i]).toString();
var pemCerts = pem.split('-----BEGIN CERTIFICATE-----');
for (var j in pemCerts) {
var k = pemCerts[j].indexOf('-----END CERTIFICATE-----');
if (k >= 0) { certs.push(pki.certificateFromPem('-----BEGIN CERTIFICATE-----' + pemCerts[j].substring(0, k) + '-----END CERTIFICATE-----')); }
}
var PemKeys = pem.split('-----BEGIN RSA PRIVATE KEY-----');
for (var j in PemKeys) {
var k = PemKeys[j].indexOf('-----END RSA PRIVATE KEY-----');
if (k >= 0) { keys.push(pki.privateKeyFromPem('-----BEGIN RSA PRIVATE KEY-----' + PemKeys[j].substring(0, k) + '-----END RSA PRIVATE KEY-----')); }
}
} catch (ex) { }
}
if ((certs.length == 0) || (keys.length != 1)) return; // No certificates or private keys
var r = { cert: certs[0], key: keys[0], extraCerts: [] }
if (certs.length > 1) { for (var i = 1; i < certs.length; i++) { r.extraCerts.push(certs[i]); } }
return r;
}
function createAuthenticodeHandler(path) {
const obj = {};
obj.header = { path: path }
// Read a file slice
function readFileSlice(start, length) {
var buffer = Buffer.alloc(length);
var len = fs.readSync(obj.fd, buffer, 0, buffer.length, start);
if (len < buffer.length) { buffer = buffer.slice(0, len); }
return buffer;
}
// Close the file
obj.close = function () {
if (obj.fd == null) return;
fs.closeSync(obj.fd);
delete obj.fd;
}
// Private OIDS
obj.Oids = {
SPC_INDIRECT_DATA_OBJID: '1.3.6.1.4.1.311.2.1.4',
SPC_STATEMENT_TYPE_OBJID: '1.3.6.1.4.1.311.2.1.11',
SPC_SP_OPUS_INFO_OBJID: '1.3.6.1.4.1.311.2.1.12',
SPC_INDIVIDUAL_SP_KEY_PURPOSE_OBJID: '1.3.6.1.4.1.311.2.1.21',
SPC_COMMERCIAL_SP_KEY_PURPOSE_OBJID: '1.3.6.1.4.1.311.2.1.22',
SPC_MS_JAVA_SOMETHING: '1.3.6.1.4.1.311.15.1',
SPC_PE_IMAGE_DATA_OBJID: '1.3.6.1.4.1.311.2.1.15',
SPC_CAB_DATA_OBJID: '1.3.6.1.4.1.311.2.1.25',
SPC_TIME_STAMP_REQUEST_OBJID: '1.3.6.1.4.1.311.3.2.1',
SPC_SIPINFO_OBJID: '1.3.6.1.4.1.311.2.1.30',
SPC_PE_IMAGE_PAGE_HASHES_V1: '1.3.6.1.4.1.311.2.3.1',
SPC_PE_IMAGE_PAGE_HASHES_V2: '1.3.6.1.4.1.311.2.3.2',
SPC_NESTED_SIGNATURE_OBJID: '1.3.6.1.4.1.311.2.4.1',
SPC_RFC3161_OBJID: '1.3.6.1.4.1.311.3.3.1'
}
// Open the file and read header information
function openFile() {
if (obj.fd != null) return true;
// Open the file descriptor
obj.path = path;
try { obj.fd = fs.openSync(path); } catch (ex) { return false; } // Unable to open file
obj.stats = fs.fstatSync(obj.fd);
obj.filesize = obj.stats.size;
if (obj.filesize < 64) { obj.close(); return false; } // File too short.
// Read the PE header size
var buf = readFileSlice(60, 4);
obj.header.header_size = buf.readUInt32LE(0);
// Check file size and PE header
if (obj.filesize < (160 + obj.header.header_size)) { obj.close(); return false; } // Invalid SizeOfHeaders.
if (readFileSlice(obj.header.header_size, 4).toString('hex') != '50450000') { obj.close(); return false; } // Invalid PE File.
// Check header magic data
var magic = readFileSlice(obj.header.header_size + 24, 2).readUInt16LE(0);
switch (magic) {
case 0x20b: obj.header.pe32plus = 1; break;
case 0x10b: obj.header.pe32plus = 0; break;
default: { obj.close(); return false; } // Invalid Magic in PE
}
// Read PE header information
obj.header.pe_checksum = readFileSlice(obj.header.header_size + 88, 4).readUInt32LE(0);
obj.header.numRVA = readFileSlice(obj.header.header_size + 116 + (obj.header.pe32plus * 16), 4).readUInt32LE(0);
buf = readFileSlice(obj.header.header_size + 152 + (obj.header.pe32plus * 16), 8);
obj.header.sigpos = buf.readUInt32LE(0);
obj.header.siglen = buf.readUInt32LE(4);
obj.header.signed = ((obj.header.sigpos != 0) && (obj.header.siglen != 0));
if (obj.header.signed) {
// Read signature block
// Check if the file size allows for the signature block
if (obj.filesize < (obj.header.sigpos + obj.header.siglen)) { obj.close(); return false; } // Executable file too short to contain the signature block.
// Remove the padding if needed
var i, pkcs7raw = readFileSlice(obj.header.sigpos + 8, obj.header.siglen - 8);
var derlen = forge.asn1.getBerValueLength(forge.util.createBuffer(pkcs7raw.slice(1, 5))) + 4;
if (derlen != pkcs7raw.length) { pkcs7raw = pkcs7raw.slice(0, derlen); }
//console.log('pkcs7raw', Buffer.from(pkcs7raw, 'binary').toString('base64'));
// Decode the signature block
var pkcs7der = forge.asn1.fromDer(forge.util.createBuffer(pkcs7raw));
// To work around ForgeJS PKCS#7 limitation, this may break PKCS7 verify if ForjeJS adds support for it in the future
// Switch content type from "1.3.6.1.4.1.311.2.1.4" to "1.2.840.113549.1.7.1"
pkcs7der.value[1].value[0].value[2].value[0].value = forge.asn1.oidToDer(forge.pki.oids.data).data;
// Decode the PKCS7 message
var pkcs7 = p7.messageFromAsn1(pkcs7der);
var pkcs7content = pkcs7.rawCapture.content.value[0];
/*
// Verify a PKCS#7 signature
// Verify is not currently supported in node-forge, but if implemented in the future, this code could work.
var caStore = forge.pki.createCaStore();
for (var i in obj.certificates) { caStore.addCertificate(obj.certificates[i]); }
// Return is true if all signatures are valid and chain up to a provided CA
if (!pkcs7.verify(caStore)) { throw ('Executable file has an invalid signature.'); }
*/
// Get the signing attributes
obj.signingAttribs = [];
for (var i in pkcs7.rawCapture.authenticatedAttributes) {
if (forge.asn1.derToOid(pkcs7.rawCapture.authenticatedAttributes[i].value[0].value) == obj.Oids.SPC_SP_OPUS_INFO_OBJID) {
for (var j in pkcs7.rawCapture.authenticatedAttributes[i].value[1].value[0].value) {
var v = pkcs7.rawCapture.authenticatedAttributes[i].value[1].value[0].value[j].value[0].value;
if (v.startsWith('http://') || v.startsWith('https://') || ((v.length % 2) == 1)) { obj.signingAttribs.push(v); } else {
var r = ""; // This string value is in UCS2 format, convert it to a normal string.
for (var k = 0; k < v.length; k += 2) { r += String.fromCharCode((v.charCodeAt(k + 8) << 8) + v.charCodeAt(k + 1)); }
obj.signingAttribs.push(r);
}
}
}
}
// Set the certificate chain
obj.certificates = pkcs7.certificates;
// Get the file hashing algorithm
var hashAlgoOid = forge.asn1.derToOid(pkcs7content.value[1].value[0].value[0].value);
switch (hashAlgoOid) {
case forge.pki.oids.sha256: { obj.fileHashAlgo = 'sha256'; break; }
case forge.pki.oids.sha384: { obj.fileHashAlgo = 'sha384'; break; }
case forge.pki.oids.sha512: { obj.fileHashAlgo = 'sha512'; break; }
case forge.pki.oids.sha224: { obj.fileHashAlgo = 'sha224'; break; }
case forge.pki.oids.md5: { obj.fileHashAlgo = 'md5'; break; }
}
// Get the signed file hash
obj.fileHashSigned = Buffer.from(pkcs7content.value[1].value[1].value, 'binary')
// Compute the actual file hash
if (obj.fileHashAlgo != null) { obj.fileHashActual = obj.getHash(obj.fileHashAlgo); }
}
return true;
}
// Hash the file using the selected hashing system
obj.getHash = function(algo) {
var hash = crypto.createHash(algo);
runHash(hash, 0, obj.header.header_size + 88);
runHash(hash, obj.header.header_size + 88 + 4, obj.header.header_size + 152 + (obj.header.pe32plus * 16));
runHash(hash, obj.header.header_size + 152 + (obj.header.pe32plus * 16) + 8, obj.header.sigpos > 0 ? obj.header.sigpos : obj.filesize);
return hash.digest();
}
// Hash the file from start to end loading 64k chunks
function runHash(hash, start, end) {
var ptr = start;
while (ptr < end) { const buf = readFileSlice(ptr, Math.min(65536, end - ptr)); hash.update(buf); ptr += buf.length; }
}
// Sign the file using the certificate and key. If none is specified, generate a dummy one
obj.sign = function (cert, args) {
if (cert == null) { cert = createSelfSignedCert({ cn: 'Test' }); }
var fileHash = obj.getHash('sha384');
// Create the signature block
var p7 = forge.pkcs7.createSignedData();
var content = { 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 0, 'type': 6, 'constructed': false, 'composed': false, 'value': forge.asn1.oidToDer('1.3.6.1.4.1.311.2.1.15').data }, { 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 0, 'type': 3, 'constructed': false, 'composed': false, 'value': '\u0000', 'bitStringContents': '\u0000', 'original': { 'tagClass': 0, 'type': 3, 'constructed': false, 'composed': false, 'value': '\u0000' } }, { 'tagClass': 128, 'type': 0, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 128, 'type': 2, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 128, 'type': 0, 'constructed': false, 'composed': false, 'value': '' }] }] }] }] }, { 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 0, 'type': 6, 'constructed': false, 'composed': false, 'value': forge.asn1.oidToDer(forge.pki.oids.sha384).data }, { 'tagClass': 0, 'type': 5, 'constructed': false, 'composed': false, 'value': '' }] }, { 'tagClass': 0, 'type': 4, 'constructed': false, 'composed': false, 'value': fileHash.toString('binary') }] }] };
p7.contentInfo = forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.SEQUENCE, true, [forge.asn1.create(forge.asn1.Class.UNIVERSAL, forge.asn1.Type.OID, false, forge.asn1.oidToDer('1.3.6.1.4.1.311.2.1.4').getBytes())]);
p7.contentInfo.value.push(forge.asn1.create(forge.asn1.Class.CONTEXT_SPECIFIC, 0, true, [content]));
p7.content = {}; // We set .contentInfo and have .content empty to bypass node-forge limitation on the type of content it can sign.
p7.addCertificate(cert.cert);
if (cert.extraCerts) { for (var i = 0; i < cert.extraCerts.length; i++) { p7.addCertificate(cert.extraCerts[0]); } } // Add any extra certificates that form the cert chain
// Build authenticated attributes
var authenticatedAttributes = [
{ type: forge.pki.oids.contentType, value: forge.pki.oids.data },
{ type: forge.pki.oids.messageDigest } // This value will populated at signing time by node-forge
]
if ((typeof args.desc == 'string') || (typeof args.url == 'string')) {
var codeSigningAttributes = { 'tagClass': 0, 'type': 16, 'constructed': true, 'composed': true, 'value': [] };
if (args.desc != null) { // Encode description as big-endian unicode.
var desc = "", ucs = Buffer.from(args.desc, 'ucs2').toString()
for (var k = 0; k < ucs.length; k += 2) { desc += String.fromCharCode(ucs.charCodeAt(k + 1), ucs.charCodeAt(k)); }
codeSigningAttributes.value.push({ 'tagClass': 128, 'type': 0, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 128, 'type': 0, 'constructed': false, 'composed': false, 'value': desc }] });
}
if (args.url != null) { codeSigningAttributes.value.push({ 'tagClass': 128, 'type': 1, 'constructed': true, 'composed': true, 'value': [{ 'tagClass': 128, 'type': 0, 'constructed': false, 'composed': false, 'value': args.url }] }); }
authenticatedAttributes.push({ type: obj.Oids.SPC_SP_OPUS_INFO_OBJID, value: codeSigningAttributes });
}
// Add the signer and sign
p7.addSigner({
key: cert.key,
certificate: cert.cert,
digestAlgorithm: forge.pki.oids.sha384,
authenticatedAttributes: authenticatedAttributes
});
p7.sign();
var p7signature = Buffer.from(forge.pkcs7.messageToPem(p7).split('-----BEGIN PKCS7-----')[1].split('-----END PKCS7-----')[0], 'base64');
//console.log('Signature', Buffer.from(p7signature, 'binary').toString('base64'));
// Open the outut file
var output = fs.openSync(args.out, 'w');
var tmp, written = 0;
var executableSize = obj.header.sigpos ? obj.header.sigpos : this.filesize;
// Compute pre-header length and copy that to the new file
var preHeaderLen = (obj.header.header_size + 152 + (obj.header.pe32plus * 16));
var tmp = readFileSlice(written, preHeaderLen);
fs.writeSync(output, tmp);
written += tmp.length;
// Quad Align the results, adding padding if necessary
var len = executableSize + p7signature.length;
var padding = (8 - ((len) % 8)) % 8;
// Write the signature header
var addresstable = Buffer.alloc(8);
addresstable.writeUInt32LE(executableSize);
addresstable.writeUInt32LE(8 + p7signature.length + padding, 4);
fs.writeSync(output, addresstable);
written += addresstable.length;
// Copy the rest of the file until the start of the signature block
while ((executableSize - written) > 0) {
tmp = readFileSlice(written, Math.min(executableSize - written, 65536));
fs.writeSync(output, tmp);
written += tmp.length;
}
// Write the signature block header and signature
var win = Buffer.alloc(8); // WIN CERTIFICATE Structure
win.writeUInt32LE(p7signature.length + padding + 8); // DWORD length
win.writeUInt16LE(512, 4); // WORD revision
win.writeUInt16LE(2, 6); // WORD type
fs.writeSync(output, win);
fs.writeSync(output, p7signature);
if (padding > 0) { fs.writeSync(output, Buffer.alloc(padding, 0)); }
// Close the file
fs.closeSync(output);
}
// Save an executable without the signature
obj.unsign = function (args) {
// Open the file
var output = fs.openSync(args.out, 'w');
var written = 0, totalWrite = obj.header.sigpos;
// Compute pre-header length and copy that to the new file
var preHeaderLen = (obj.header.header_size + 152 + (obj.header.pe32plus * 16));
var tmp = readFileSlice(written, preHeaderLen);
fs.writeSync(output, tmp);
written += tmp.length;
// Write the new signature header
fs.writeSync(output, Buffer.alloc(8));
written += 8;
// Copy the rest of the file until the start of the signature block
while ((totalWrite - written) > 0) {
tmp = readFileSlice(written, Math.min(totalWrite - written, 65536));
fs.writeSync(output, tmp);
written += tmp.length;
}
fs.closeSync(output);
}
// Return null if we could not open the file
return (openFile() ? obj : null);
}
function start() {
// Parse the arguments
const args = require('minimist')(process.argv.slice(2));
// Show tool help
if (process.argv.length < 3) {
console.log("MeshCentral Authenticode Tool.");
console.log("Usage:");
console.log(" node authenticode.js [command] [options]");
console.log("Commands:");
console.log(" info: Show information about an executable.");
console.log(" --json Show information in JSON format.");
console.log(" sign: Sign an executable.");
console.log(" --exe [file] Required executable to sign.");
console.log(" --out [file] Resulting signed executable.");
console.log(" --pem [pemfile] Certificate & private key to sign the executable with.");
console.log(" --desc [description] Description string to embbed into signature.");
console.log(" --url [url] URL to embbed into signature.");
console.log(" unsign: Remove the signature from the executable.");
console.log(" --exe [file] Required executable to un-sign.");
console.log(" --out [file] Resulting executable with signature removed.");
console.log(" createcert: Create a code signging self-signed certificate and key.");
console.log(" --out [pemfile] Required certificate file to create.");
console.log(" --cn [value] Required certificate common name.");
console.log(" --country [value] Certificate country name.");
console.log(" --state [value] Certificate state name.");
console.log(" --locality [value] Certificate locality name.");
console.log(" --org [value] Certificate organization name.");
console.log(" --ou [value] Certificate organization unit name.");
console.log(" --serial [value] Certificate serial number.");
console.log("");
console.log("Note that certificate PEM files must first have the signing certificate,");
console.log("followed by all certificates that form the trust chain.");
return;
}
// Check that a valid command is passed in
if (['info', 'sign', 'unsign', 'createcert'].indexOf(process.argv[2].toLowerCase()) == -1) {
console.log("Invalid command: " + process.argv[2]);
console.log("Valid commands are: info, sign, unsign, createcert");
return;
}
var exe = null;
if (args.exe) {
// Check the file exists and open the file
var stats = null;
try { stats = require('fs').statSync(args.exe); } catch (ex) { }
if (stats == null) { console.log("Unable to executable open file: " + args.exe); return; }
exe = createAuthenticodeHandler(args.exe);
}
// Execute the command
var command = process.argv[2].toLowerCase();
if (command == 'info') { // Get signature information about an executable
if (exe == null) { console.log("Missing --exe [filename]"); return; }
if (args.json) {
var r = { header: exe.header, filesize: exe.filesize }
if (exe.fileHashAlgo != null) { r.hashMethod = exe.fileHashAlgo; }
if (exe.fileHashSigned != null) { r.hashSigned = exe.fileHashSigned.toString('hex'); }
if (exe.fileHashActual != null) { r.hashActual = exe.fileHashActual.toString('hex'); }
if (exe.signingAttribs && exe.signingAttribs.length > 0) { r.signAttributes = exe.signingAttribs; }
console.log(JSON.stringify(r, null, 2));
} else {
console.log("Header", exe.header);
if (exe.fileHashAlgo != null) { console.log("Hash Method:", exe.fileHashAlgo); }
if (exe.fileHashSigned != null) { console.log("Signed Hash:", exe.fileHashSigned.toString('hex')); }
if (exe.fileHashActual != null) { console.log("Actual Hash:", exe.fileHashActual.toString('hex')); }
if (exe.signingAttribs && exe.signingAttribs.length > 0) { console.log("Signature Attributes:"); for (var i in exe.signingAttribs) { console.log(' ' + exe.signingAttribs[i]); } }
console.log("File Length: " + exe.filesize);
}
}
if (command == 'sign') { // Sign an executable
if (typeof args.exe != 'string') { console.log("Missing --exe [filename]"); return; }
createOutFile(args, args.exe);
const cert = loadCertificates(args.pem);
if (cert == null) { console.log("Unable to load certificate and/or private key, generating test certificate."); }
console.log("Signing to " + args.out); exe.sign(cert, args); console.log("Done.");
}
if (command == 'unsign') { // Unsign an executable
if (typeof args.exe != 'string') { console.log("Missing --exe [filename]"); return; }
createOutFile(args, args.exe);
if (exe.header.signed) { console.log("Unsigning to " + args.out); exe.unsign(args); console.log("Done."); } else { console.log("Executable is not signed."); }
}
if (command == 'createcert') { // Create a code signing certificate and private key
if (typeof args.out != 'string') { console.log("Missing --out [filename]"); return; }
if (typeof args.cn != 'string') { console.log("Missing --cn [name]"); return; }
if (typeof args.serial == 'string') { if (args.serial != parseInt(args.serial)) { console.log("Invalid serial number."); return; } else { args.serial = parseInt(args.serial); } }
if (typeof args.serial == 'number') { args.serial = '0' + args.serial; } // Serial number must be a integer string with a single leading '0'
const cert = createSelfSignedCert(args);
console.log("Writing to " + args.out);
fs.writeFileSync(args.out, pki.certificateToPem(cert.cert) + '\r\n' + pki.privateKeyToPem(cert.key));
console.log("Done.");
}
// Close the file
if (exe != null) { exe.close(); }
}
// If this is the main module, run the command line version
if (require.main === module) { start(); }
// Exports
module.exports.createAuthenticodeHandler = createAuthenticodeHandler;
module.exports.loadCertificates = loadCertificates;
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