250 lines
8.5 KiB
C#
250 lines
8.5 KiB
C#
/*
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Copyright (C) 2011 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 Mono.Cecil;
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using Mono.Cecil.Cil;
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using Mono.MyStuff;
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using de4dot.blocks;
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namespace de4dot.deobfuscators.dotNET_Reactor {
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class MethodsDecrypter {
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ModuleDefinition module;
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EncryptedResource encryptedResource;
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long xorKey;
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bool useXorKey;
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public bool Detected {
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get { return encryptedResource.ResourceDecrypterMethod != null; }
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}
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public MethodDefinition MethodsDecrypterMethod {
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get { return encryptedResource.ResourceDecrypterMethod; }
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}
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public EmbeddedResource MethodsResource {
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get { return encryptedResource.EncryptedDataResource; }
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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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}
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public void find() {
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var additionalTypes = new string[] {
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// "System.Diagnostics.StackFrame", //TODO: Not in DNR <= 3.7.0.3
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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 info in DotNetUtils.getCalledMethods(module, cctor)) {
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var method = info.Item2;
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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 (info.Item1.BaseType == null || info.Item1.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.ResourceDecrypterMethod = (MethodDefinition)callCounter.most();
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}
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public bool decrypt(PE.PeImage peImage, ISimpleDeobfuscator simpleDeobfuscator, ref Dictionary<uint, DumpedMethod> dumpedMethods) {
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if (encryptedResource.ResourceDecrypterMethod == null)
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return false;
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encryptedResource.init(simpleDeobfuscator);
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initXorKey();
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var methodsData = encryptedResource.decrypt();
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ArrayFinder arrayFinder = new ArrayFinder(encryptedResource.ResourceDecrypterMethod);
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bool hooksJitter = arrayFinder.exists(new byte[] { (byte)'g', (byte)'e', (byte)'t', (byte)'J', (byte)'i', (byte)'t' });
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if (useXorKey) {
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// DNR 4.3, 4.4
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var stream = new MemoryStream(methodsData);
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var reader = new BinaryReader(stream);
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var writer = new BinaryWriter(stream);
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int count = methodsData.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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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 (4.0-4.2?), 4.3, 4.4 (jitter is hooked)
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var metadataTables = peImage.Cor20Header.createMetadataTables();
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var methodDef = metadataTables.getMetadataType(PE.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 Dictionary<uint, DumpedMethod>();
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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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if (isNativeCode) {
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//TODO: Convert to CIL code
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Log.w("Found native code. Ignoring it for now... Assembly won't run. token: {0:X8}", 0x06000001 + methodIndex);
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}
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else {
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var dm = new DumpedMethod();
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dm.token = (uint)(0x06000001 + methodIndex);
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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[dm.token] = dm;
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}
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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(PE.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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void initXorKey() {
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useXorKey = false;
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var instructions = encryptedResource.ResourceDecrypterMethod.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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xorKey = DotNetUtils.getLdcI4Value(ldci4);
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useXorKey = true;
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return;
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}
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}
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}
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}
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