357 lines
12 KiB
C#
357 lines
12 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 dot10.DotNet;
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using dot10.DotNet.Emit;
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using Mono.MyStuff;
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using de4dot.blocks;
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using de4dot.PE;
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namespace de4dot.code.deobfuscators.dotNET_Reactor.v4 {
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class MethodsDecrypter {
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ModuleDefinition module;
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EncryptedResource encryptedResource;
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Dictionary<uint, byte[]> tokenToNativeMethod = new Dictionary<uint, byte[]>();
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Dictionary<MethodDef, byte[]> methodToNativeMethod = new Dictionary<MethodDef, byte[]>();
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int totalEncryptedNativeMethods = 0;
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long xorKey;
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public bool Detected {
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get { return encryptedResource.Method != null; }
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}
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public bool HasNativeMethods {
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get { return methodToNativeMethod.Count > 0; }
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}
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public TypeDef DecrypterType {
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get { return encryptedResource.Type; }
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}
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public MethodDef Method {
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get { return encryptedResource.Method; }
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}
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public EmbeddedResource Resource {
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get { return encryptedResource.Resource; }
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}
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public MethodsDecrypter(ModuleDefinition module) {
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this.module = module;
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this.encryptedResource = new EncryptedResource(module);
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}
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public MethodsDecrypter(ModuleDefinition module, MethodsDecrypter oldOne) {
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this.module = module;
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this.encryptedResource = new EncryptedResource(module, oldOne.encryptedResource);
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this.tokenToNativeMethod = oldOne.tokenToNativeMethod;
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this.totalEncryptedNativeMethods = oldOne.totalEncryptedNativeMethods;
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this.xorKey = oldOne.xorKey;
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}
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public void find() {
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var additionalTypes = new string[] {
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"System.IntPtr",
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// "System.Reflection.Assembly", //TODO: Not in unknown DNR version with jitter support
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};
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var checkedMethods = new Dictionary<MethodReferenceAndDeclaringTypeKey, bool>();
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var callCounter = new CallCounter();
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int typesLeft = 30;
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foreach (var type in module.GetTypes()) {
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var cctor = DotNetUtils.getMethod(type, ".cctor");
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if (cctor == null || cctor.Body == null)
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continue;
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if (typesLeft-- <= 0)
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break;
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foreach (var method in DotNetUtils.getCalledMethods(module, cctor)) {
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var key = new MethodReferenceAndDeclaringTypeKey(method);
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if (!checkedMethods.ContainsKey(key)) {
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checkedMethods[key] = false;
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if (method.DeclaringType.BaseType == null || method.DeclaringType.BaseType.FullName != "System.Object")
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continue;
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if (!DotNetUtils.isMethod(method, "System.Void", "()"))
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continue;
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if (!encryptedResource.couldBeResourceDecrypter(method, additionalTypes))
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continue;
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checkedMethods[key] = true;
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}
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else if (!checkedMethods[key])
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continue;
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callCounter.add(method);
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}
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}
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encryptedResource.Method = (MethodDef)callCounter.most();
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}
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void xorEncrypt(byte[] data) {
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if (xorKey == 0)
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return;
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var stream = new MemoryStream(data);
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var reader = new BinaryReader(stream);
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var writer = new BinaryWriter(stream);
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int count = data.Length / 8;
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for (int i = 0; i < count; i++) {
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long val = reader.ReadInt64();
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val ^= xorKey;
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stream.Position -= 8;
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writer.Write(val);
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}
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}
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static short[] nativeLdci4 = new short[] { 0x55, 0x8B, 0xEC, 0xB8, -1, -1, -1, -1, 0x5D, 0xC3 };
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static short[] nativeLdci4_0 = new short[] { 0x55, 0x8B, 0xEC, 0x33, 0xC0, 0x5D, 0xC3 };
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public bool decrypt(PeImage peImage, ISimpleDeobfuscator simpleDeobfuscator, ref DumpedMethods dumpedMethods, Dictionary<uint, byte[]> tokenToNativeCode) {
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if (encryptedResource.Method == null)
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return false;
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encryptedResource.init(simpleDeobfuscator);
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if (!encryptedResource.FoundResource)
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return false;
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var methodsData = encryptedResource.decrypt();
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bool hooksJitter = findDnrCompileMethod(encryptedResource.Method.DeclaringType) != null;
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xorKey = getXorKey();
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xorEncrypt(methodsData);
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var methodsDataReader = new BinaryReader(new MemoryStream(methodsData));
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int patchCount = methodsDataReader.ReadInt32();
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int mode = methodsDataReader.ReadInt32();
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int tmp = methodsDataReader.ReadInt32();
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methodsDataReader.BaseStream.Position -= 4;
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if ((tmp & 0xFF000000) == 0x06000000) {
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// It's method token + rva. DNR 3.7.0.3 (and earlier?) - 3.9.0.1
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methodsDataReader.BaseStream.Position += 8L * patchCount;
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patchCount = methodsDataReader.ReadInt32();
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mode = methodsDataReader.ReadInt32();
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patchDwords(peImage, methodsDataReader, patchCount);
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while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
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uint token = methodsDataReader.ReadUInt32();
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int numDwords = methodsDataReader.ReadInt32();
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patchDwords(peImage, methodsDataReader, numDwords / 2);
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}
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}
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else if (!hooksJitter || mode == 1) {
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// DNR 3.9.8.0, 4.0, 4.1, 4.2, 4.3, 4.4
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patchDwords(peImage, methodsDataReader, patchCount);
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while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
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uint rva = methodsDataReader.ReadUInt32();
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uint token = methodsDataReader.ReadUInt32(); // token, unknown, or index
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int size = methodsDataReader.ReadInt32();
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if (size > 0)
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peImage.dotNetSafeWrite(rva, methodsDataReader.ReadBytes(size));
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}
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}
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else {
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// DNR 4.0 - 4.4 (jitter is hooked)
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var metadataTables = peImage.Cor20Header.createMetadataTables();
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var methodDef = metadataTables.getMetadataType(MetadataIndex.iMethodDef);
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var rvaToIndex = new Dictionary<uint, int>((int)methodDef.rows);
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uint offset = methodDef.fileOffset;
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for (int i = 0; i < methodDef.rows; i++) {
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uint rva = peImage.offsetReadUInt32(offset);
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offset += methodDef.totalSize;
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if (rva == 0)
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continue;
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if ((peImage.readByte(rva) & 3) == 2)
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rva++;
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else
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rva += (uint)(4 * (peImage.readByte(rva + 1) >> 4));
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rvaToIndex[rva] = i;
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}
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patchDwords(peImage, methodsDataReader, patchCount);
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int count = methodsDataReader.ReadInt32();
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dumpedMethods = new DumpedMethods();
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while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
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uint rva = methodsDataReader.ReadUInt32();
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uint index = methodsDataReader.ReadUInt32();
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bool isNativeCode = index >= 0x70000000;
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int size = methodsDataReader.ReadInt32();
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var methodData = methodsDataReader.ReadBytes(size);
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int methodIndex;
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if (!rvaToIndex.TryGetValue(rva, out methodIndex)) {
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Log.w("Could not find method having code RVA {0:X8}", rva);
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continue;
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}
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uint methodToken = 0x06000001 + (uint)methodIndex;
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if (isNativeCode) {
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totalEncryptedNativeMethods++;
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if (tokenToNativeCode != null)
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tokenToNativeCode[methodToken] = methodData;
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// Convert return true / false methods. The others are converted to
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// throw 0xDEADCODE.
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if (DeobUtils.isCode(nativeLdci4, methodData)) {
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uint val = BitConverter.ToUInt32(methodData, 4);
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// ldc.i4 XXXXXXXXh / ret
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methodData = new byte[] { 0x20, 0, 0, 0, 0, 0x2A };
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methodData[1] = (byte)val;
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methodData[2] = (byte)(val >> 8);
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methodData[3] = (byte)(val >> 16);
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methodData[4] = (byte)(val >> 24);
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}
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else if (DeobUtils.isCode(nativeLdci4_0, methodData)) {
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// ldc.i4.0 / ret
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methodData = new byte[] { 0x16, 0x2A };
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}
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else {
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tokenToNativeMethod[methodToken] = methodData;
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// ldc.i4 0xDEADCODE / conv.u4 / throw
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methodData = new byte[] { 0x20, 0xDE, 0xC0, 0xAD, 0xDE, 0x6D, 0x7A };
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}
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}
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var dm = new DumpedMethod();
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dm.token = methodToken;
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dm.code = methodData;
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offset = methodDef.fileOffset + (uint)(methodIndex * methodDef.totalSize);
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rva = peImage.offsetReadUInt32(offset);
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dm.mdImplFlags = peImage.offsetReadUInt16(offset + (uint)methodDef.fields[1].offset);
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dm.mdFlags = peImage.offsetReadUInt16(offset + (uint)methodDef.fields[2].offset);
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dm.mdName = peImage.offsetRead(offset + (uint)methodDef.fields[3].offset, methodDef.fields[3].size);
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dm.mdSignature = peImage.offsetRead(offset + (uint)methodDef.fields[4].offset, methodDef.fields[4].size);
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dm.mdParamList = peImage.offsetRead(offset + (uint)methodDef.fields[5].offset, methodDef.fields[5].size);
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if ((peImage.readByte(rva) & 3) == 2) {
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dm.mhFlags = 2;
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dm.mhMaxStack = 8;
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dm.mhCodeSize = (uint)dm.code.Length;
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dm.mhLocalVarSigTok = 0;
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}
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else {
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dm.mhFlags = peImage.readUInt16(rva);
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dm.mhMaxStack = peImage.readUInt16(rva + 2);
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dm.mhCodeSize = (uint)dm.code.Length;
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dm.mhLocalVarSigTok = peImage.readUInt32(rva + 8);
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}
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dumpedMethods.add(dm);
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}
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}
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return true;
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}
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static void patchDwords(PeImage peImage, BinaryReader reader, int count) {
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for (int i = 0; i < count; i++) {
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uint rva = reader.ReadUInt32();
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uint data = reader.ReadUInt32();
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peImage.dotNetSafeWrite(rva, BitConverter.GetBytes(data));
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}
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}
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long getXorKey() {
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var instructions = encryptedResource.Method.Body.Instructions;
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for (int i = 0; i < instructions.Count - 1; i++) {
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if (instructions[i].OpCode.Code != Code.Ldind_I8)
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continue;
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var ldci4 = instructions[i + 1];
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if (!DotNetUtils.isLdcI4(ldci4))
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continue;
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return DotNetUtils.getLdcI4Value(ldci4);
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}
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return 0;
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}
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public void reloaded() {
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foreach (var pair in tokenToNativeMethod) {
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int token = (int)pair.Key;
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var method = module.LookupToken(token) as MethodDef;
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if (method == null)
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throw new ApplicationException(string.Format("Could not find method {0:X8}", token));
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methodToNativeMethod[method] = pair.Value;
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}
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tokenToNativeMethod = null;
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}
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public void encryptNativeMethods(MetadataBuilder builder) {
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if (methodToNativeMethod.Count == 0)
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return;
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Log.v("Encrypting native methods");
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var stream = new MemoryStream();
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var writer = new BinaryWriter(stream);
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writer.Write((uint)0); // patch count
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writer.Write((uint)0); // mode
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writer.Write(methodToNativeMethod.Count);
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int index = 0;
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var codeWriter = builder.CodeWriter;
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foreach (var pair in methodToNativeMethod) {
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var method = pair.Key;
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if (method.DeclaringType == null)
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continue; // Method was removed
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if (method.DeclaringType.Module == null)
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continue; // method.DeclaringType was removed
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var code = pair.Value;
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uint codeRva = builder.GetMethodBodyRva((int)method.MDToken.RID - 1);
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if ((codeWriter.ReadByteAtRva(codeRva) & 3) == 2)
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codeRva++;
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else
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codeRva += 4 * (uint)(codeWriter.ReadByteAtRva(codeRva + 1) >> 4);
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Log.v("Native method {0:X8}, code RVA {1:X8}", method.MDToken.ToInt32(), codeRva);
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writer.Write(codeRva);
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writer.Write(0x70000000 + index++);
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writer.Write(code.Length);
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writer.Write(code);
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}
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if (index != 0)
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Log.n("Re-encrypted {0}/{1} native methods", index, totalEncryptedNativeMethods);
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var encryptedData = stream.ToArray();
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xorEncrypt(encryptedData);
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encryptedResource.updateResource(encryptedResource.encrypt(encryptedData));
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}
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public static MethodDef findDnrCompileMethod(TypeDef type) {
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foreach (var method in type.Methods) {
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if (!method.IsStatic || method.Body == null)
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continue;
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if (method.Parameters.Count != 6)
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continue;
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if (!DotNetUtils.isMethod(method, "System.UInt32", "(System.UInt64&,System.IntPtr,System.IntPtr,System.UInt32,System.IntPtr&,System.UInt32&)"))
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continue;
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return method;
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}
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return null;
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}
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}
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}
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