228 lines
5.6 KiB
C#
228 lines
5.6 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.Collections.Generic;
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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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using de4dot.blocks.cflow;
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namespace de4dot.code.deobfuscators.DeepSea {
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class ArrayBlockDeobfuscator : BlockDeobfuscator {
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ArrayBlockState arrayBlockState;
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Dictionary<Local, ArrayBlockState.FieldInfo> localToInfo = new Dictionary<Local, ArrayBlockState.FieldInfo>();
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DsConstantsReader constantsReader;
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public ArrayBlockDeobfuscator(ArrayBlockState arrayBlockState) {
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this.arrayBlockState = arrayBlockState;
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}
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public override void DeobfuscateBegin(Blocks blocks) {
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base.DeobfuscateBegin(blocks);
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InitLocalToInfo();
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}
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void InitLocalToInfo() {
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localToInfo.Clear();
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foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count - 1; i++) {
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var ldsfld = instrs[i];
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if (ldsfld.OpCode.Code != Code.Ldsfld)
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continue;
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var stloc = instrs[i + 1];
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if (!stloc.IsStloc())
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continue;
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var info = arrayBlockState.GetFieldInfo((IField)ldsfld.Operand);
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if (info == null)
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continue;
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var local = stloc.Instruction.GetLocal(blocks.Locals);
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if (local == null)
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continue;
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localToInfo[local] = info;
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}
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}
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}
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protected override bool Deobfuscate(Block block) {
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bool modified = false;
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constantsReader = null;
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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bool ch = Deobfuscate1(block, i);
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if (ch) {
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modified = true;
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continue;
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}
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ch = Deobfuscate2(block, i);
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if (ch) {
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modified = true;
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continue;
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}
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ch = Deobfuscate3(block, i);
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if (ch) {
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modified = true;
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continue;
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}
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}
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return modified;
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}
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static bool IsLdelem(ArrayBlockState.FieldInfo info, Code code) {
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switch (info.elementType) {
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case ElementType.Boolean:
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case ElementType.I1:
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case ElementType.U1:
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return code == Code.Ldelem_I1 || code == Code.Ldelem_U1;
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case ElementType.Char:
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case ElementType.I2:
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case ElementType.U2:
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return code == Code.Ldelem_I2 || code == Code.Ldelem_U2;
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case ElementType.I4:
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case ElementType.U4:
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return code == Code.Ldelem_I4 || code == Code.Ldelem_U4;
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default:
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return false;
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}
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}
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static bool IsStelem(ArrayBlockState.FieldInfo info, Code code) {
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switch (info.elementType) {
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case ElementType.Boolean:
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case ElementType.I1:
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case ElementType.U1:
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return code == Code.Stelem_I1;
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case ElementType.Char:
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case ElementType.I2:
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case ElementType.U2:
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return code == Code.Stelem_I2;
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case ElementType.I4:
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case ElementType.U4:
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return code == Code.Stelem_I4;
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default:
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return false;
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}
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}
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bool Deobfuscate1(Block block, int i) {
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var instrs = block.Instructions;
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if (i >= instrs.Count - 2)
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return false;
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var ldloc = instrs[i];
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if (!ldloc.IsLdloc())
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return false;
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var local = ldloc.Instruction.GetLocal(blocks.Locals);
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if (local == null)
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return false;
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ArrayBlockState.FieldInfo info;
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if (!localToInfo.TryGetValue(local, out info))
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return false;
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var ldci4 = instrs[i + 1];
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if (!ldci4.IsLdcI4())
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return false;
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var ldelem = instrs[i + 2];
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if (!IsLdelem(info, ldelem.OpCode.Code))
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return false;
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block.Remove(i, 3 - 1);
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instrs[i] = new Instr(Instruction.CreateLdcI4((int)info.ReadArrayElement(ldci4.GetLdcI4Value())));
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return true;
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}
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bool Deobfuscate2(Block block, int i) {
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var instrs = block.Instructions;
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if (i >= instrs.Count - 2)
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return false;
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var ldsfld = instrs[i];
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if (ldsfld.OpCode.Code != Code.Ldsfld)
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return false;
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var info = arrayBlockState.GetFieldInfo(ldsfld.Operand as IField);
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if (info == null)
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return false;
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var ldci4 = instrs[i + 1];
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if (!ldci4.IsLdcI4())
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return false;
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var ldelem = instrs[i + 2];
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if (!IsLdelem(info, ldelem.OpCode.Code))
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return false;
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block.Remove(i, 3 - 1);
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instrs[i] = new Instr(Instruction.CreateLdcI4((int)info.ReadArrayElement(ldci4.GetLdcI4Value())));
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return true;
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}
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bool Deobfuscate3(Block block, int i) {
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var instrs = block.Instructions;
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if (i + 1 >= instrs.Count)
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return false;
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int start = i;
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var ldsfld = instrs[i];
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if (ldsfld.OpCode.Code != Code.Ldsfld)
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return false;
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var info = arrayBlockState.GetFieldInfo(ldsfld.Operand as IField);
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if (info == null)
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return false;
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if (!instrs[i + 1].IsLdcI4())
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return false;
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var constants = GetConstantsReader(block);
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int value;
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i += 2;
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if (!constants.GetInt32(ref i, out value))
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return false;
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if (i >= instrs.Count)
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return false;
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var stelem = instrs[i];
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if (!IsStelem(info, stelem.OpCode.Code))
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return false;
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block.Remove(start, i - start + 1);
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return true;
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}
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DsConstantsReader GetConstantsReader(Block block) {
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if (constantsReader != null)
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return constantsReader;
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return constantsReader = new DsConstantsReader(block.Instructions);
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}
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}
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}
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