601 lines
19 KiB
C#
601 lines
19 KiB
C#
/*
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Copyright (C) 2011-2012 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Text;
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using Mono.MyStuff;
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using de4dot.PE;
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namespace de4dot.code.deobfuscators.MaxtoCode {
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// Decrypts methods and resources
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class MethodsDecrypter {
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DecrypterInfo decrypterInfo;
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class MethodInfos {
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MainType mainType;
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PeImage peImage;
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PeHeader peHeader;
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McKey mcKey;
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uint structSize;
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uint methodInfosOffset;
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uint encryptedDataOffset;
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uint xorKey;
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Dictionary<uint, DecryptedMethodInfo> infos = new Dictionary<uint, DecryptedMethodInfo>();
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List<IDecrypter> decrypters = new List<IDecrypter>();
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const int ENCRYPTED_DATA_INFO_SIZE = 0x13;
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delegate byte[] Decrypt(byte[] encrypted);
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readonly Decrypt[] decryptHandlersV1;
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readonly Decrypt[] decryptHandlersV2;
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readonly Decrypt[] decryptHandlersV3;
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readonly Decrypt[] decryptHandlersV4;
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readonly Decrypt[] decryptHandlersV5a;
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readonly Decrypt[] decryptHandlersV5b;
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readonly Decrypt[] decryptHandlersV5c;
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public class DecryptedMethodInfo {
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public uint bodyRva;
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public byte[] body;
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public DecryptedMethodInfo(uint bodyRva, byte[] body) {
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this.bodyRva = bodyRva;
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this.body = body;
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}
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}
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public MethodInfos(MainType mainType, PeImage peImage, PeHeader peHeader, McKey mcKey) {
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this.mainType = mainType;
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this.peImage = peImage;
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this.peHeader = peHeader;
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this.mcKey = mcKey;
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decryptHandlersV1 = new Decrypt[] { decrypt1a, decrypt4a, decrypt2a, decrypt3a, decrypt5, decrypt6, decrypt7 };
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decryptHandlersV2 = new Decrypt[] { decrypt3a, decrypt2a, decrypt1a, decrypt4a, decrypt5, decrypt6, decrypt7 };
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decryptHandlersV3 = new Decrypt[] { decrypt1a, decrypt2a, decrypt3a, decrypt4a, decrypt5, decrypt6, decrypt7 };
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decryptHandlersV4 = new Decrypt[] { decrypt2a, decrypt1a, decrypt3a, decrypt4a, decrypt5, decrypt6, decrypt7 };
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decryptHandlersV5a = new Decrypt[] { decrypt4a, decrypt2a, decrypt3a, decrypt1a, decrypt5, decrypt6, decrypt7 };
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decryptHandlersV5b = new Decrypt[] { decrypt4b, decrypt2b, decrypt3b, decrypt1b, decrypt6, decrypt7, decrypt5 };
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decryptHandlersV5c = new Decrypt[] { decrypt4c, decrypt2c, decrypt3c, decrypt1c, decrypt6, decrypt7, decrypt5 };
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structSize = getStructSize(mcKey);
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uint methodInfosRva = peHeader.getRva(0x0FF8, mcKey.readUInt32(0x005A));
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uint encryptedDataRva = peHeader.getRva(0x0FF0, mcKey.readUInt32(0x0046));
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methodInfosOffset = peImage.rvaToOffset(methodInfosRva);
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encryptedDataOffset = peImage.rvaToOffset(encryptedDataRva);
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}
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static uint getStructSize(McKey mcKey) {
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uint magicLo = mcKey.readUInt32(0x8C0);
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uint magicHi = mcKey.readUInt32(0x8C4);
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foreach (var info in EncryptionInfos.McKey8C0h) {
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if (magicLo == info.MagicLo && magicHi == info.MagicHi)
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return 0xC + 6 * ENCRYPTED_DATA_INFO_SIZE;
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}
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return 0xC + 3 * ENCRYPTED_DATA_INFO_SIZE;
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}
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EncryptionVersion getVersion() {
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if (peHeader.EncryptionVersion != EncryptionVersion.Unknown)
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return peHeader.EncryptionVersion;
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uint m2lo = mcKey.readUInt32(0x8C0);
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uint m2hi = mcKey.readUInt32(0x8C4);
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foreach (var info in EncryptionInfos.McKey8C0h) {
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if (info.MagicLo == m2lo && info.MagicHi == m2hi)
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return info.Version;
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}
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Log.w("Could not detect MC version. Magic2: {0:X8} {1:X8}", m2lo, m2hi);
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return EncryptionVersion.Unknown;
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}
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public DecryptedMethodInfo lookup(uint bodyRva) {
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DecryptedMethodInfo info;
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infos.TryGetValue(bodyRva, out info);
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return info;
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}
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byte readByte(uint offset) {
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return peImage.offsetReadByte(methodInfosOffset + offset);
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}
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short readInt16(uint offset) {
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return (short)peImage.offsetReadUInt16(methodInfosOffset + offset);
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}
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uint readUInt32(uint offset) {
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return peImage.offsetReadUInt32(methodInfosOffset + offset);
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}
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int readInt32(uint offset) {
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return (int)readUInt32(offset);
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}
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short readEncryptedInt16(uint offset) {
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return (short)(readInt16(offset) ^ xorKey);
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}
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int readEncryptedInt32(uint offset) {
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return (int)readEncryptedUInt32(offset);
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}
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uint readEncryptedUInt32(uint offset) {
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return readUInt32(offset) ^ xorKey;
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}
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interface IDecrypter {
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byte[] decrypt(int type, byte[] encrypted);
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}
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class Decrypter : IDecrypter {
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Decrypt[] decrypterHandlers;
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public Decrypter(Decrypt[] decrypterHandlers) {
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this.decrypterHandlers = decrypterHandlers;
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}
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public byte[] decrypt(int type, byte[] encrypted) {
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if (1 <= type && type <= decrypterHandlers.Length)
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return decrypterHandlers[type - 1](encrypted);
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throw new ApplicationException(string.Format("Invalid encryption type: {0:X2}", type));
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}
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}
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void initializeDecrypter() {
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switch (getVersion()) {
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case EncryptionVersion.V1: decrypters.Add(new Decrypter(decryptHandlersV1)); break;
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case EncryptionVersion.V2: decrypters.Add(new Decrypter(decryptHandlersV2)); break;
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case EncryptionVersion.V3: decrypters.Add(new Decrypter(decryptHandlersV3)); break;
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case EncryptionVersion.V4: decrypters.Add(new Decrypter(decryptHandlersV4)); break;
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case EncryptionVersion.V5:
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decrypters.Add(new Decrypter(decryptHandlersV5a));
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decrypters.Add(new Decrypter(decryptHandlersV5b));
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decrypters.Add(new Decrypter(decryptHandlersV5c));
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break;
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case EncryptionVersion.Unknown:
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default:
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throw new ApplicationException("Unknown MC version");
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}
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}
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public void initializeInfos() {
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initializeDecrypter();
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if (!initializeInfos2())
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throw new ApplicationException("Could not decrypt methods");
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}
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bool initializeInfos2() {
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foreach (var decrypter in decrypters) {
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try {
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if (initializeInfos2(decrypter))
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return true;
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}
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catch {
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}
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}
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return false;
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}
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bool initializeInfos2(IDecrypter decrypter) {
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int numMethods = readInt32(0) ^ readInt32(4);
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if (numMethods < 0)
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throw new ApplicationException("Invalid number of encrypted methods");
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xorKey = (uint)numMethods;
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int numEncryptedDataInfos = ((int)structSize - 0xC) / ENCRYPTED_DATA_INFO_SIZE;
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var encryptedDataInfos = new byte[numEncryptedDataInfos][];
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uint offset = 8;
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for (int i = 0; i < numMethods; i++, offset += structSize) {
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uint methodBodyRva = readEncryptedUInt32(offset);
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uint totalSize = readEncryptedUInt32(offset + 4);
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uint methodInstructionRva = readEncryptedUInt32(offset + 8);
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// Read the method body header and method body (instrs + exception handlers).
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// The method body header is always in the first one. The instrs + ex handlers
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// are always in the last 4, and evenly divided (each byte[] is totalLen / 4).
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// The 2nd one is for the exceptions (or padding), but it may be null.
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uint offset2 = offset + 0xC;
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int exOffset = 0;
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for (int j = 0; j < encryptedDataInfos.Length; j++, offset2 += ENCRYPTED_DATA_INFO_SIZE) {
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// readByte(offset2); <-- index
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int encryptionType = readEncryptedInt16(offset2 + 1);
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uint dataOffset = readEncryptedUInt32(offset2 + 3);
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uint encryptedSize = readEncryptedUInt32(offset2 + 7);
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uint realSize = readEncryptedUInt32(offset2 + 11);
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if (j == 1)
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exOffset = readEncryptedInt32(offset2 + 15);
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if (j == 1 && exOffset == 0)
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encryptedDataInfos[j] = null;
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else
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encryptedDataInfos[j] = decrypt(decrypter, encryptionType, dataOffset, encryptedSize, realSize);
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}
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var decryptedData = new byte[totalSize];
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int copyOffset = 0;
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copyOffset = copyData(decryptedData, encryptedDataInfos[0], copyOffset);
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for (int j = 2; j < encryptedDataInfos.Length; j++)
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copyOffset = copyData(decryptedData, encryptedDataInfos[j], copyOffset);
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copyData(decryptedData, encryptedDataInfos[1], exOffset); // Exceptions or padding
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if (!MethodBodyParser.verify(decryptedData))
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throw new InvalidMethodBody();
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var info = new DecryptedMethodInfo(methodBodyRva, decryptedData);
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infos[info.bodyRva] = info;
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}
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return true;
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}
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static int copyData(byte[] dest, byte[] source, int offset) {
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if (source == null)
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return offset;
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Array.Copy(source, 0, dest, offset, source.Length);
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return offset + source.Length;
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}
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byte[] readData(uint offset, int size) {
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return peImage.offsetReadBytes(encryptedDataOffset + offset, size);
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}
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byte[] decrypt(IDecrypter decrypter, int type, uint dataOffset, uint encryptedSize, uint realSize) {
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if (realSize == 0)
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return null;
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if (realSize > encryptedSize)
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throw new ApplicationException("Invalid realSize");
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var encrypted = readData(dataOffset, (int)encryptedSize);
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var decrypted = decrypter.decrypt(type, encrypted);
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if (realSize > decrypted.Length)
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throw new ApplicationException("Invalid decrypted length");
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Array.Resize(ref decrypted, (int)realSize);
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return decrypted;
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}
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byte[] decrypt1a(byte[] encrypted) {
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return decrypt1(encrypted, 0, 0, 0x2000);
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}
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byte[] decrypt1b(byte[] encrypted) {
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return decrypt1(encrypted, 6, 6, 0x500);
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}
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byte[] decrypt1c(byte[] encrypted) {
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return decrypt1(encrypted, 6, 0, 0x1000);
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}
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byte[] decrypt1(byte[] encrypted, int keyStart, int keyReset, int keyEnd) {
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var decrypted = new byte[encrypted.Length];
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for (int i = 0, ki = keyStart; i < decrypted.Length; i++) {
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decrypted[i] = (byte)(encrypted[i] ^ mcKey.readByte(ki));
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if (++ki == keyEnd)
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ki = keyReset;
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}
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return decrypted;
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}
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byte[] decrypt2a(byte[] encrypted) {
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return decrypt2(encrypted, 0x00FA);
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}
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byte[] decrypt2b(byte[] encrypted) {
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return decrypt2(encrypted, 0x00FA + 9);
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}
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byte[] decrypt2c(byte[] encrypted) {
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return decrypt2(encrypted, 0x00FA + 0x24);
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}
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byte[] decrypt2(byte[] encrypted, int offset) {
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if ((encrypted.Length & 7) != 0)
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throw new ApplicationException("Invalid encryption #2 length");
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uint key4 = mcKey.readUInt32(offset + 4 * 4);
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uint key5 = mcKey.readUInt32(offset + 5 * 4);
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byte[] decrypted = new byte[encrypted.Length & ~7];
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var writer = new BinaryWriter(new MemoryStream(decrypted));
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int loopCount = encrypted.Length / 8;
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for (int i = 0; i < loopCount; i++) {
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uint val0 = BitConverter.ToUInt32(encrypted, i * 8);
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uint val1 = BitConverter.ToUInt32(encrypted, i * 8 + 4);
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uint x = (val1 >> 26) + (val0 << 6);
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uint y = (val0 >> 26) + (val1 << 6);
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writer.Write(x ^ key4);
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writer.Write(y ^ key5);
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}
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return decrypted;
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}
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byte[] decrypt3a(byte[] encrypted) {
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return decrypt3(encrypted, 0x015E);
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}
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byte[] decrypt3b(byte[] encrypted) {
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return decrypt3(encrypted, 0x015E + 0xE5);
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}
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byte[] decrypt3c(byte[] encrypted) {
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return decrypt3(encrypted, 0x015E + 0x28);
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}
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static readonly byte[] decrypt3Shifts = new byte[16] { 5, 11, 14, 21, 6, 20, 17, 29, 4, 10, 3, 2, 7, 1, 26, 18 };
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byte[] decrypt3(byte[] encrypted, int offset) {
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if ((encrypted.Length & 7) != 0)
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throw new ApplicationException("Invalid encryption #3 length");
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uint key0 = mcKey.readUInt32(offset + 0 * 4);
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uint key3 = mcKey.readUInt32(offset + 3 * 4);
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byte[] decrypted = new byte[encrypted.Length & ~7];
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var writer = new BinaryWriter(new MemoryStream(decrypted));
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int loopCount = encrypted.Length / 8;
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for (int i = 0; i < loopCount; i++) {
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uint x = BitConverter.ToUInt32(encrypted, i * 8);
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uint y = BitConverter.ToUInt32(encrypted, i * 8 + 4);
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foreach (var shift in decrypt3Shifts) {
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int shift1 = 32 - shift;
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uint x1 = (y >> shift1) + (x << shift);
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uint y1 = (x >> shift1) + (y << shift);
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x = x1;
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y = y1;
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}
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writer.Write(x ^ key0);
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writer.Write(y ^ key3);
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}
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return decrypted;
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}
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byte[] decrypt4a(byte[] encrypted) {
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return decrypt4(encrypted, 0, 0, 0x2000);
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}
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byte[] decrypt4b(byte[] encrypted) {
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return decrypt4(encrypted, 0x14, 0x14, 0x1000);
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}
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byte[] decrypt4c(byte[] encrypted) {
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return decrypt4(encrypted, 5, 0, 0x2000);
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}
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byte[] decrypt4(byte[] encrypted, int keyStart, int keyReset, int keyEnd) {
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var decrypted = new byte[encrypted.Length / 3 * 2 + 1];
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int count = encrypted.Length / 3;
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int i = 0, ki = keyStart, j = 0;
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while (count-- > 0) {
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byte k1 = mcKey.readByte(ki + 1);
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byte k2 = mcKey.readByte(ki + 2);
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byte k3 = mcKey.readByte(ki + 3);
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decrypted[j++] = (byte)(((encrypted[i + 1] ^ k2) >> 4) | ((encrypted[i] ^ k1) & 0xF0));
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decrypted[j++] = (byte)(((encrypted[i + 1] ^ k2) << 4) + ((encrypted[i + 2] ^ k3) & 0x0F));
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i += 3;
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ki += 4;
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if (ki == keyEnd)
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ki = keyReset;
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}
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if ((encrypted.Length % 3) != 0)
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decrypted[j] = (byte)(encrypted[i] ^ mcKey.readByte(ki));
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return decrypted;
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}
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byte[] decrypt5(byte[] encrypted) {
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return CryptDecrypter.decrypt(mcKey.readBytes(0x0032, 15), encrypted);
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}
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byte[] decrypt6(byte[] encrypted) {
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return Decrypter6.decrypt(mcKey.readBytes(0x0096, 32), encrypted);
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}
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byte[] decrypt7(byte[] encrypted) {
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var decrypted = (byte[])encrypted.Clone();
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new Blowfish(getBlowfishKey()).decrypt_LE(decrypted);
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return decrypted;
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}
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byte[] blowfishKey;
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byte[] getBlowfishKey() {
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if (blowfishKey != null)
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return blowfishKey;
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var key = new byte[100];
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int i;
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for (i = 0; i < key.Length; i++) {
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byte b = mcKey.readByte(i);
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if (b == 0)
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break;
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key[i] = b;
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}
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for (; i < key.Length; i++)
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key[i] = 0;
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key[key.Length - 1] = 0;
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return blowfishKey = key;
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}
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}
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public MethodsDecrypter(DecrypterInfo decrypterInfo) {
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this.decrypterInfo = decrypterInfo;
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}
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public bool decrypt(ref DumpedMethods dumpedMethods) {
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dumpedMethods = decryptMethods();
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if (dumpedMethods == null)
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return false;
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decryptResources();
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decryptStrings();
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return true;
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}
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DumpedMethods decryptMethods() {
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var dumpedMethods = new DumpedMethods();
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var peImage = decrypterInfo.peImage;
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var methodInfos = new MethodInfos(decrypterInfo.mainType, peImage, decrypterInfo.peHeader, decrypterInfo.mcKey);
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methodInfos.initializeInfos();
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var metadataTables = peImage.Cor20Header.createMetadataTables();
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var methodDef = metadataTables.getMetadataType(MetadataIndex.iMethodDef);
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uint methodDefOffset = methodDef.fileOffset;
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for (int i = 0; i < methodDef.rows; i++, methodDefOffset += methodDef.totalSize) {
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uint bodyRva = peImage.offsetReadUInt32(methodDefOffset);
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if (bodyRva == 0)
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continue;
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var info = methodInfos.lookup(bodyRva);
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if (info == null)
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continue;
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uint bodyOffset = peImage.rvaToOffset(bodyRva);
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ushort magic = peImage.offsetReadUInt16(bodyOffset);
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if (magic != 0xFFF3)
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continue;
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var dm = new DumpedMethod();
|
|
dm.token = (uint)(0x06000001 + i);
|
|
dm.mdImplFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[1].offset);
|
|
dm.mdFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[2].offset);
|
|
dm.mdName = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[3].offset, methodDef.fields[3].size);
|
|
dm.mdSignature = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[4].offset, methodDef.fields[4].size);
|
|
dm.mdParamList = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[5].offset, methodDef.fields[5].size);
|
|
|
|
var reader = new BinaryReader(new MemoryStream(info.body));
|
|
byte b = reader.ReadByte();
|
|
if ((b & 3) == 2) {
|
|
dm.mhFlags = 2;
|
|
dm.mhMaxStack = 8;
|
|
dm.mhCodeSize = (uint)(b >> 2);
|
|
dm.mhLocalVarSigTok = 0;
|
|
}
|
|
else {
|
|
reader.BaseStream.Position--;
|
|
dm.mhFlags = reader.ReadUInt16();
|
|
dm.mhMaxStack = reader.ReadUInt16();
|
|
dm.mhCodeSize = reader.ReadUInt32();
|
|
dm.mhLocalVarSigTok = reader.ReadUInt32();
|
|
uint codeOffset = (uint)(dm.mhFlags >> 12) * 4;
|
|
reader.BaseStream.Position += codeOffset - 12;
|
|
}
|
|
|
|
dm.code = reader.ReadBytes((int)dm.mhCodeSize);
|
|
if ((dm.mhFlags & 8) != 0) {
|
|
reader.BaseStream.Position = (reader.BaseStream.Position + 3) & ~3;
|
|
dm.extraSections = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
|
|
}
|
|
|
|
dumpedMethods.add(dm);
|
|
}
|
|
|
|
return dumpedMethods;
|
|
}
|
|
|
|
void decryptResources() {
|
|
var peHeader = decrypterInfo.peHeader;
|
|
var mcKey = decrypterInfo.mcKey;
|
|
var peImage = decrypterInfo.peImage;
|
|
var fileData = decrypterInfo.fileData;
|
|
|
|
uint resourceRva = peHeader.getRva(0x0E10, mcKey.readUInt32(0x00A0));
|
|
uint resourceSize = peHeader.readUInt32(0x0E14) ^ mcKey.readUInt32(0x00AA);
|
|
if (resourceRva == 0 || resourceSize == 0)
|
|
return;
|
|
if (resourceRva != peImage.Cor20Header.resources.virtualAddress ||
|
|
resourceSize != peImage.Cor20Header.resources.size) {
|
|
Log.w("Invalid resource RVA and size found");
|
|
}
|
|
|
|
Log.v("Decrypting resources @ RVA {0:X8}, {1} bytes", resourceRva, resourceSize);
|
|
|
|
int resourceOffset = (int)peImage.rvaToOffset(resourceRva);
|
|
for (int i = 0; i < resourceSize; i++)
|
|
fileData[resourceOffset + i] ^= mcKey[i % 0x2000];
|
|
}
|
|
|
|
void decryptStrings() {
|
|
var peHeader = decrypterInfo.peHeader;
|
|
var mcKey = decrypterInfo.mcKey;
|
|
var peImage = decrypterInfo.peImage;
|
|
var fileData = decrypterInfo.fileData;
|
|
|
|
uint usHeapRva = peHeader.getRva(0x0E00, mcKey.readUInt32(0x0078));
|
|
uint usHeapSize = peHeader.readUInt32(0x0E04) ^ mcKey.readUInt32(0x0082);
|
|
if (usHeapRva == 0 || usHeapSize == 0)
|
|
return;
|
|
var usHeap = peImage.Cor20Header.metadata.getStream("#US");
|
|
if (usHeap == null ||
|
|
peImage.rvaToOffset(usHeapRva) != usHeap.fileOffset ||
|
|
usHeapSize != usHeap.Length) {
|
|
Log.w("Invalid #US heap RVA and size found");
|
|
}
|
|
|
|
Log.v("Decrypting strings @ RVA {0:X8}, {1} bytes", usHeapRva, usHeapSize);
|
|
Log.indent();
|
|
|
|
int mcKeyOffset = 0;
|
|
int usHeapOffset = (int)peImage.rvaToOffset(usHeapRva);
|
|
int usHeapEnd = usHeapOffset + (int)usHeapSize;
|
|
usHeapOffset++;
|
|
while (usHeapOffset < usHeapEnd) {
|
|
if (fileData[usHeapOffset] == 0 || fileData[usHeapOffset] == 1) {
|
|
usHeapOffset++;
|
|
continue;
|
|
}
|
|
|
|
int usHeapOffsetOrig = usHeapOffset;
|
|
int stringDataLength = DeobUtils.readVariableLengthInt32(fileData, ref usHeapOffset);
|
|
int usHeapOffsetString = usHeapOffset;
|
|
int encryptedLength = stringDataLength - (usHeapOffset - usHeapOffsetOrig == 1 ? 1 : 2);
|
|
for (int i = 0; i < encryptedLength; i++) {
|
|
byte k = mcKey.readByte(mcKeyOffset++ % 0x2000);
|
|
fileData[usHeapOffset] = rolb((byte)(fileData[usHeapOffset] ^ k), 3);
|
|
usHeapOffset++;
|
|
}
|
|
|
|
try {
|
|
Log.v("Decrypted string: {0}", Utils.toCsharpString(Encoding.Unicode.GetString(fileData, usHeapOffsetString, stringDataLength - 1)));
|
|
}
|
|
catch {
|
|
Log.v("Could not decrypt string at offset {0:X8}", usHeapOffsetOrig);
|
|
}
|
|
|
|
usHeapOffset++;
|
|
}
|
|
|
|
Log.deIndent();
|
|
}
|
|
|
|
byte rolb(byte b, int n) {
|
|
return (byte)((b << n) | (b >> (8 - n)));
|
|
}
|
|
}
|
|
}
|