514 lines
16 KiB
C#
514 lines
16 KiB
C#
/*
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Copyright (C) 2011-2014 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.Text;
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using dnlib.IO;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Confuser {
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abstract class ConstantsDecrypterBase : IVersionProvider {
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protected ModuleDefMD module;
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protected byte[] fileData;
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protected ISimpleDeobfuscator simpleDeobfuscator;
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protected MethodDef nativeMethod;
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MethodDefAndDeclaringTypeDict<DecrypterInfo> methodToDecrypterInfo = new MethodDefAndDeclaringTypeDict<DecrypterInfo>();
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FieldDefAndDeclaringTypeDict<bool> fields = new FieldDefAndDeclaringTypeDict<bool>();
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protected EmbeddedResource resource;
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protected IBinaryReader reader;
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public class DecrypterInfo {
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public MethodDef decryptMethod;
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public uint key0, key1, key2, key3;
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public byte doubleType, singleType, int32Type, int64Type, stringType;
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public void Initialize() {
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if (!InitializeKeys())
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throw new ApplicationException("Could not find all keys");
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if (!InitializeTypeCodes())
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throw new ApplicationException("Could not find all type codes");
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}
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protected virtual bool InitializeKeys() {
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if (!FindKey0(decryptMethod, out key0))
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return false;
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if (!FindKey1(decryptMethod, out key1))
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return false;
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if (!FindKey2Key3(decryptMethod, out key2, out key3))
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return false;
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return true;
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}
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protected static bool FindKey0(MethodDef method, out uint key) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 5; i++) {
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if (!instrs[i].IsLdloc())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Or)
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continue;
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var ldci4 = instrs[i + 2];
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if (!ldci4.IsLdcI4())
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continue;
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if (instrs[i + 3].OpCode.Code != Code.Xor)
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continue;
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if (instrs[i + 4].OpCode.Code != Code.Add)
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continue;
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if (!instrs[i + 5].IsStloc())
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continue;
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key = (uint)ldci4.GetLdcI4Value();
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return true;
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}
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key = 0;
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return false;
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}
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static bool FindKey1(MethodDef method, out uint key) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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int index = ConfuserUtils.FindCallMethod(instrs, i, Code.Callvirt, "System.Int32 System.Reflection.MemberInfo::get_MetadataToken()");
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if (index < 0)
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break;
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if (index + 2 > instrs.Count)
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break;
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if (!instrs[index + 1].IsStloc())
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continue;
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var ldci4 = instrs[index + 2];
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if (!ldci4.IsLdcI4())
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continue;
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key = (uint)ldci4.GetLdcI4Value();
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return true;
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}
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key = 0;
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return false;
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}
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protected static bool FindKey2Key3(MethodDef method, out uint key2, out uint key3) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 3; i++) {
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var ldci4_1 = instrs[i];
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if (!ldci4_1.IsLdcI4())
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continue;
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if (!instrs[i + 1].IsStloc())
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continue;
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var ldci4_2 = instrs[i + 2];
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if (!ldci4_2.IsLdcI4())
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continue;
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if (!instrs[i + 3].IsStloc())
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continue;
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key2 = (uint)ldci4_1.GetLdcI4Value();
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key3 = (uint)ldci4_2.GetLdcI4Value();
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return true;
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}
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key2 = 0;
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key3 = 0;
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return false;
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}
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bool InitializeTypeCodes() {
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var allBlocks = new Blocks(decryptMethod).MethodBlocks.GetAllBlocks();
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if (!FindTypeCode(allBlocks, out doubleType, Code.Call, "System.Double System.BitConverter::ToDouble(System.Byte[],System.Int32)"))
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return false;
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if (!FindTypeCode(allBlocks, out singleType, Code.Call, "System.Single System.BitConverter::ToSingle(System.Byte[],System.Int32)"))
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return false;
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if (!FindTypeCode(allBlocks, out int32Type, Code.Call, "System.Int32 System.BitConverter::ToInt32(System.Byte[],System.Int32)"))
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return false;
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if (!FindTypeCode(allBlocks, out int64Type, Code.Call, "System.Int64 System.BitConverter::ToInt64(System.Byte[],System.Int32)"))
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return false;
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if (!FindTypeCode(allBlocks, out stringType, Code.Callvirt, "System.String System.Text.Encoding::GetString(System.Byte[])") &&
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!FindTypeCode(allBlocks, out stringType, Code.Callvirt, "System.String System.Text.Encoding::GetString(System.Byte[],System.Int32,System.Int32)"))
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return false;
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return true;
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}
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static bool FindTypeCode(IList<Block> allBlocks, out byte typeCode, Code callCode, string bitConverterMethod) {
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foreach (var block in allBlocks) {
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if (block.Sources.Count != 1)
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continue;
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int index = ConfuserUtils.FindCallMethod(block.Instructions, 0, callCode, bitConverterMethod);
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if (index < 0)
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continue;
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if (!FindTypeCode(block.Sources[0], out typeCode))
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continue;
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return true;
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}
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typeCode = 0;
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return false;
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}
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static Block FixBlock(Block block) {
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if (block.Sources.Count != 1)
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return block;
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if (block.GetOnlyTarget() == null)
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return block;
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if (block.Instructions.Count == 0) {
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}
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else if (block.Instructions.Count == 1 && block.Instructions[0].OpCode.Code == Code.Nop) {
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}
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else
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return block;
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return block.Sources[0];
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}
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static bool FindTypeCode(Block block, out byte typeCode) {
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block = FixBlock(block);
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var instrs = block.Instructions;
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int numCeq = 0;
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for (int i = instrs.Count - 1; i >= 0; i--) {
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var instr = instrs[i];
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if (instr.OpCode.Code == Code.Ceq) {
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numCeq++;
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continue;
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}
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if (!instr.Instruction.IsLdcI4())
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continue;
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if (numCeq != 0 && numCeq != 2)
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continue;
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typeCode = (byte)instr.Instruction.GetLdcI4Value();
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return true;
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}
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typeCode = 0;
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return false;
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}
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public uint CalcHash(uint x) {
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uint h0 = key1 ^ x;
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uint h1 = key2;
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uint h2 = key3;
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for (uint i = 1; i <= 64; i++) {
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h0 = (h0 << 8) | (h0 >> 24);
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uint n = h0 & 0x3F;
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if (n >= 0 && n < 16) {
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h1 |= ((byte)(h0 >> 8) & (h0 >> 16)) ^ (byte)~h0;
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h2 ^= (h0 * i + 1) & 0xF;
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h0 += (h1 | h2) ^ key0;
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}
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else if (n >= 16 && n < 32) {
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h1 ^= ((h0 & 0x00FF00FF) << 8) ^ (ushort)((h0 >> 8) | ~h0);
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h2 += (h0 * i) & 0x1F;
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h0 |= (h1 + ~h2) & key0;
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}
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else if (n >= 32 && n < 48) {
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h1 += (byte)(h0 | (h0 >> 16)) + (~h0 & 0xFF);
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h2 -= ~(h0 + n) % 48;
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h0 ^= (h1 % h2) | key0;
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}
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else if (n >= 48 && n < 64) {
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h1 ^= ((byte)(h0 >> 16) | ~(h0 & 0xFF)) * (~h0 & 0x00FF0000);
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h2 += (h0 ^ (i - 1)) % n;
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h0 -= ~(h1 ^ h2) + key0;
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}
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}
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return h0;
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}
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}
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public abstract bool Detected { get; }
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public MethodDef NativeMethod {
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get { return nativeMethod; }
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}
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public EmbeddedResource Resource {
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get { return resource; }
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}
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public IEnumerable<FieldDef> Fields {
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get { return fields.GetKeys(); }
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}
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protected bool HasDecrypterInfos {
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get { return methodToDecrypterInfo.Count > 0; }
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}
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public IEnumerable<DecrypterInfo> DecrypterInfos {
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get { return methodToDecrypterInfo.GetValues(); }
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}
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public ConstantsDecrypterBase(ModuleDefMD module, byte[] fileData, ISimpleDeobfuscator simpleDeobfuscator) {
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this.module = module;
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this.fileData = fileData;
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this.simpleDeobfuscator = simpleDeobfuscator;
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}
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public abstract bool GetRevisionRange(out int minRev, out int maxRev);
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public abstract void Initialize();
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protected void Add(DecrypterInfo info) {
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methodToDecrypterInfo.Add(info.decryptMethod, info);
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}
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protected bool Add(FieldDef field) {
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if (field == null)
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return false;
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fields.Add(field, true);
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return true;
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}
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protected void InitializeDecrypterInfos() {
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foreach (var info in methodToDecrypterInfo.GetValues()) {
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simpleDeobfuscator.Deobfuscate(info.decryptMethod);
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info.Initialize();
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}
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}
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protected void SetConstantsData(byte[] constants) {
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reader = MemoryImageStream.Create(constants);
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}
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protected EmbeddedResource FindResource(MethodDef method) {
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return DotNetUtils.GetResource(module, DotNetUtils.GetCodeStrings(method)) as EmbeddedResource;
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}
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protected static MethodDef FindNativeMethod(MethodDef method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var call = instrs[i];
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if (call.OpCode.Code != Code.Call)
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continue;
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var calledMethod = call.Operand as MethodDef;
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if (calledMethod == null || !calledMethod.IsStatic || !calledMethod.IsNative)
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continue;
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if (!DotNetUtils.IsMethod(calledMethod, "System.Int32", "(System.Int32)"))
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continue;
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return calledMethod;
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}
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return null;
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}
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static Local GetDynamicLocal_v17_r73740(MethodDef method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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i = ConfuserUtils.FindCallMethod(instrs, i, Code.Callvirt, "System.Byte System.IO.BinaryReader::ReadByte()");
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if (i < 0 || i + 5 >= instrs.Count)
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break;
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if (!instrs[i + 1].IsStloc())
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continue;
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var ldloc = instrs[i + 2];
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if (!ldloc.IsLdloc())
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continue;
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if (!instrs[i + 3].IsLdloc())
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continue;
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var ldci4 = instrs[i + 4];
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if (!ldci4.IsLdcI4() || ldci4.GetLdcI4Value() != 0x7F)
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continue;
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if (instrs[i + 5].OpCode.Code != Code.And)
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continue;
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return ldloc.GetLocal(method.Body.Variables);
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}
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return null;
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}
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static int GetDynamicEndIndex_v17_r73740(MethodDef method, Local local) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 5; i++) {
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int index = i;
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var stloc = instrs[index++];
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if (!stloc.IsStloc() || stloc.GetLocal(method.Body.Variables) != local)
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continue;
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if (!instrs[index++].IsLdloc())
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continue;
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if (instrs[index].OpCode.Code == Code.Call) {
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if (i + 7 >= instrs.Count)
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continue;
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index++;
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if (!instrs[index++].IsLdloc())
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continue;
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}
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if (!instrs[index++].IsLdloc())
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continue;
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var ldloc = instrs[index++];
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if (!ldloc.IsLdloc() || ldloc.GetLocal(method.Body.Variables) != local)
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continue;
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if (instrs[index++].OpCode.Code != Code.Conv_U1)
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continue;
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if (instrs[index++].OpCode.Code != Code.Stelem_I1)
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continue;
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return i;
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}
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return -1;
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}
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static int GetDynamicEndIndex_v17_r74788(MethodDef method, Local local) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 11; i++) {
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var stloc = instrs[i];
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if (!stloc.IsStloc() || stloc.GetLocal(method.Body.Variables) != local)
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continue;
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if (!instrs[i + 1].IsLdloc())
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continue;
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if (!instrs[i + 2].IsLdloc())
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continue;
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if (!instrs[i + 3].IsLdloc())
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continue;
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if (!instrs[i + 4].IsLdloc())
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continue;
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if (!instrs[i + 5].IsLdloc())
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continue;
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var ldci4 = instrs[i + 6];
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if (!ldci4.IsLdcI4() || (ldci4.GetLdcI4Value() != 8 && ldci4.GetLdcI4Value() != 16))
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continue;
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if (instrs[i + 7].OpCode.Code != Code.Rem)
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continue;
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if (instrs[i + 8].OpCode.Code != Code.Ldelem_U1)
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continue;
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if (instrs[i + 9].OpCode.Code != Code.Xor)
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continue;
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if (instrs[i + 10].OpCode.Code != Code.Conv_U1)
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continue;
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if (instrs[i + 11].OpCode.Code != Code.Stelem_I1)
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continue;
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return i;
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}
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return -1;
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}
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static int GetDynamicStartIndex_v17_r73740(MethodDef method, int endIndex) {
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if (endIndex < 0)
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return -1;
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var instrs = method.Body.Instructions;
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for (int i = endIndex; i >= 0; i--) {
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if (i == 0)
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return i == endIndex ? -1 : i + 1;
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if (instrs[i].OpCode.FlowControl == FlowControl.Next)
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continue;
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return i + 1;
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}
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return -1;
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}
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static readonly byte[] defaultDecryptKey_v17 = new byte[1];
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protected byte[] DecryptConstant_v17_r73740_dynamic(DecrypterInfo info, byte[] encrypted, uint offs, uint key) {
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return DecryptConstant_v17_r73740_dynamic(info, encrypted, offs, key, defaultDecryptKey_v17);
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}
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protected byte[] DecryptConstant_v17_r73740_dynamic(DecrypterInfo info, byte[] encrypted, uint offs, uint key1, byte[] key2) {
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var local = GetDynamicLocal_v17_r73740(info.decryptMethod);
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if (local == null)
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throw new ApplicationException("Could not find local");
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int endIndex = GetDynamicEndIndex_v17_r73740(info.decryptMethod, local);
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if (endIndex < 0)
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endIndex = GetDynamicEndIndex_v17_r74788(info.decryptMethod, local);
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int startIndex = GetDynamicStartIndex_v17_r73740(info.decryptMethod, endIndex);
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if (startIndex < 0)
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throw new ApplicationException("Could not find start/end index");
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var constReader = new ConstantsReader(info.decryptMethod);
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return Decrypt(encrypted, key1, (magic, i) => {
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constReader.SetConstantInt32(local, magic);
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int index = startIndex, result;
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if (!constReader.GetNextInt32(ref index, out result) || index != endIndex)
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throw new ApplicationException("Could not decrypt integer");
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return (byte)(result ^ key2[i % key2.Length]);
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});
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}
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protected byte[] DecryptConstant_v17_r73764_native(DecrypterInfo info, byte[] encrypted, uint offs, uint key) {
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return DecryptConstant_v17_r73764_native(info, encrypted, offs, key, defaultDecryptKey_v17);
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}
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protected byte[] DecryptConstant_v17_r73764_native(DecrypterInfo info, byte[] encrypted, uint offs, uint key1, byte[] key2) {
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using (var x86Emu = new x86Emulator(fileData))
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return Decrypt(encrypted, key1, (magic, i) => (byte)(x86Emu.Emulate((uint)nativeMethod.RVA, magic) ^ key2[i % key2.Length]));
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}
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static byte[] Decrypt(byte[] encrypted, uint key, Func<uint, int, byte> decryptFunc) {
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var reader = MemoryImageStream.Create(encrypted);
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var decrypted = new byte[reader.ReadInt32() ^ key];
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for (int i = 0; i < decrypted.Length; i++) {
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uint magic = reader.Read7BitEncodedUInt32();
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decrypted[i] = decryptFunc(magic, i);
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}
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return decrypted;
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}
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public object DecryptInt32(MethodDef caller, MethodDef decryptMethod, object[] args) {
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var info = methodToDecrypterInfo.Find(decryptMethod);
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byte typeCode;
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var data = DecryptData(info, caller, args, out typeCode);
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if (typeCode != info.int32Type)
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return null;
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if (data.Length != 4)
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throw new ApplicationException("Invalid data length");
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return BitConverter.ToInt32(data, 0);
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}
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public object DecryptInt64(MethodDef caller, MethodDef decryptMethod, object[] args) {
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var info = methodToDecrypterInfo.Find(decryptMethod);
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byte typeCode;
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var data = DecryptData(info, caller, args, out typeCode);
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if (typeCode != info.int64Type)
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return null;
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if (data.Length != 8)
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throw new ApplicationException("Invalid data length");
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return BitConverter.ToInt64(data, 0);
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}
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public object DecryptSingle(MethodDef caller, MethodDef decryptMethod, object[] args) {
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var info = methodToDecrypterInfo.Find(decryptMethod);
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byte typeCode;
|
|
var data = DecryptData(info, caller, args, out typeCode);
|
|
if (typeCode != info.singleType)
|
|
return null;
|
|
if (data.Length != 4)
|
|
throw new ApplicationException("Invalid data length");
|
|
return BitConverter.ToSingle(data, 0);
|
|
}
|
|
|
|
public object DecryptDouble(MethodDef caller, MethodDef decryptMethod, object[] args) {
|
|
var info = methodToDecrypterInfo.Find(decryptMethod);
|
|
byte typeCode;
|
|
var data = DecryptData(info, caller, args, out typeCode);
|
|
if (typeCode != info.doubleType)
|
|
return null;
|
|
if (data.Length != 8)
|
|
throw new ApplicationException("Invalid data length");
|
|
return BitConverter.ToDouble(data, 0);
|
|
}
|
|
|
|
public string DecryptString(MethodDef caller, MethodDef decryptMethod, object[] args) {
|
|
var info = methodToDecrypterInfo.Find(decryptMethod);
|
|
byte typeCode;
|
|
var data = DecryptData(info, caller, args, out typeCode);
|
|
if (typeCode != info.stringType)
|
|
return null;
|
|
return Encoding.UTF8.GetString(data);
|
|
}
|
|
|
|
protected abstract byte[] DecryptData(DecrypterInfo info, MethodDef caller, object[] args, out byte typeCode);
|
|
}
|
|
}
|