/** * @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(args) { var certs = [], keys = [], pemFileNames = args.pem; 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); 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;