108 lines
3.1 KiB
C#
108 lines
3.1 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.Collections.Generic;
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using Mono.Cecil;
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using Mono.Cecil.Cil;
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using de4dot.blocks;
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namespace de4dot.blocks.cflow {
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// Very simple constants folder which is all that's needed at the moment
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class ConstantsFolder {
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List<Block> allBlocks;
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Blocks blocks;
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InstructionEmulator instructionEmulator = new InstructionEmulator();
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List<ParameterDefinition> args;
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public void init(Blocks blocks, List<Block> allBlocks) {
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this.blocks = blocks;
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this.allBlocks = allBlocks;
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args = DotNetUtils.getParameters(blocks.Method);
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}
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public bool deobfuscate() {
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bool changed = false;
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foreach (var block in allBlocks) {
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instructionEmulator.init(blocks);
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var instr = instrs[i];
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switch (instr.OpCode.Code) {
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case Code.Ldarg:
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case Code.Ldarg_0:
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case Code.Ldarg_1:
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case Code.Ldarg_2:
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case Code.Ldarg_3:
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case Code.Ldarg_S:
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changed |= fixLoadInstruction(block, i, instructionEmulator.getArg(DotNetUtils.getParameter(args, instr.Instruction)));
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break;
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case Code.Ldloc:
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case Code.Ldloc_0:
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case Code.Ldloc_1:
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case Code.Ldloc_2:
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case Code.Ldloc_3:
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case Code.Ldloc_S:
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changed |= fixLoadInstruction(block, i, instructionEmulator.getLocal(DotNetUtils.getLocalVar(blocks.Locals, instr.Instruction)));
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break;
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case Code.Ldarga:
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case Code.Ldarga_S:
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instructionEmulator.makeArgUnknown((ParameterDefinition)instr.Operand);
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break;
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case Code.Ldloca:
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case Code.Ldloca_S:
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instructionEmulator.makeLocalUnknown((VariableDefinition)instr.Operand);
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break;
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}
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try {
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instructionEmulator.emulate(instr.Instruction);
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}
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catch (System.NullReferenceException) {
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// Here if eg. invalid metadata token in a call instruction (operand is null)
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break;
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}
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}
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}
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return changed;
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}
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bool fixLoadInstruction(Block block, int index, Value value) {
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if (value.isInt32()) {
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var intValue = (Int32Value)value;
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if (!intValue.allBitsValid())
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return false;
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block.Instructions[index] = new Instr(DotNetUtils.createLdci4(intValue.value));
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return true;
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}
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else if (value.isInt64()) {
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var intValue = (Int64Value)value;
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if (!intValue.allBitsValid())
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return false;
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block.Instructions[index] = new Instr(Instruction.Create(OpCodes.Ldc_I8, intValue.value));
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return true;
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}
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return false;
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}
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}
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}
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