330 lines
8.0 KiB
C#
330 lines
8.0 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.Text;
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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.code.deobfuscators.Eazfuscator_NET {
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class DecrypterType {
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TypeDefinition type;
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MethodDefinition int64Method;
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bool initialized;
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ulong l1;
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int i1, i2, i3;
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int m1_i1, m2_i1, m2_i2, m3_i1;
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int token1, token2, token3, token4, token5, token6;
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public TypeDefinition Type {
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get { return type; }
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set {
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if (type == null)
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type = value;
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else if (type != value)
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throw new ApplicationException("Found another one");
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}
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}
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public bool Detected {
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get { return type != null; }
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}
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public bool initialize() {
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if (initialized)
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return true;
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int64Method = findInt64Method();
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if (int64Method == null)
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return false;
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if (!findInt1And2())
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return false;
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if (!findInt3())
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return false;
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if (!findMethodInts())
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return false;
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token1 = getToken(-1509110933);
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token2 = getToken(-82806859);
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token3 = getToken(1294352278);
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token4 = getToken(402344241);
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token5 = getToken(-56237163);
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token6 = getToken(1106695601);
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if (token1 == 0 || token2 == 0 || token3 == 0)
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return false;
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if (token4 == 0 || token5 == 0 || token6 == 0)
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return false;
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initialized = true;
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return true;
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}
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MethodDefinition findInt64Method() {
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if (type == null)
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return null;
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foreach (var method in type.Methods) {
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if (!method.IsStatic || method.Body == null || method.HasGenericParameters)
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continue;
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if (!DotNetUtils.isMethod(method, "System.Int64", "()"))
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continue;
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if (!findInt64(method))
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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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bool findInt64(MethodDefinition method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 1; i++) {
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var ldci8 = instrs[i];
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if (ldci8.OpCode.Code != Code.Ldc_I8)
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Xor)
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continue;
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l1 = (ulong)(long)ldci8.Operand;
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return true;
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}
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return false;
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}
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bool findInt1And2() {
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var consts = getConstants(findNestedTypeMethod(1294352278));
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if (consts.Count != 2)
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return false;
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i1 = consts[0];
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i2 = consts[1];
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return true;
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}
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bool findInt3() {
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var consts = getConstants(findNestedTypeMethod(1106695601));
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if (consts.Count != 1)
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return false;
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i3 = consts[0];
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return true;
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}
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bool findMethodInts() {
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foreach (var nestedType in type.NestedTypes) {
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var methods = getBinaryIntMethods(nestedType);
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if (methods.Count < 3)
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continue;
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if (!findMethod1Int(methods))
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continue;
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if (!findMethod2Int(methods))
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continue;
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if (!findMethod3Int(methods))
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continue;
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return true;
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}
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return false;
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}
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static List<MethodDefinition> getBinaryIntMethods(TypeDefinition type) {
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var list = new List<MethodDefinition>();
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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 (!DotNetUtils.isMethod(method, "System.Int32", "(System.Int32,System.Int32)"))
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continue;
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list.Add(method);
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}
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return list;
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}
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bool findMethod1Int(IEnumerable<MethodDefinition> methods) {
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foreach (var method in methods) {
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if (countInstructions(method, Code.Ldarg_0) != 1)
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continue;
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var constants = getConstants(method);
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if (constants.Count != 1)
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continue;
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m1_i1 = constants[0];
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return true;
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}
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return false;
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}
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bool findMethod2Int(IEnumerable<MethodDefinition> methods) {
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foreach (var method in methods) {
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var constants = getConstants(method);
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if (constants.Count != 2)
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continue;
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m2_i1 = constants[0];
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m2_i2 = constants[1];
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return true;
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}
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return false;
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}
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bool findMethod3Int(IEnumerable<MethodDefinition> methods) {
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foreach (var method in methods) {
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if (countInstructions(method, Code.Ldarg_0) != 2)
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continue;
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var constants = getConstants(method);
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if (constants.Count != 1)
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continue;
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m3_i1 = constants[0];
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return true;
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}
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return false;
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}
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static int countInstructions(MethodDefinition method, Code code) {
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int count = 0;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code == code)
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count++;
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}
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return count;
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}
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static List<int> getConstants(MethodDefinition method) {
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var list = new List<int>();
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if (method == null)
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return list;
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int index = 0;
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var instrs = method.Body.Instructions;
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while (true) {
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int val;
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if (!EfUtils.getNextInt32(method, ref index, out val))
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break;
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if (index + 1 < instrs.Count && instrs[index].OpCode.Code != Code.Ret)
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list.Add(val);
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}
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return list;
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}
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MethodDefinition findNestedTypeMethod(int constant) {
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foreach (var nestedType in type.NestedTypes) {
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foreach (var method in nestedType.Methods) {
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if (!method.IsStatic || method.Body == null)
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continue;
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 1; i++) {
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var ldci4 = instrs[i];
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if (!DotNetUtils.isLdcI4(ldci4))
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continue;
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if (DotNetUtils.getLdcI4Value(ldci4) != constant)
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Ret)
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continue;
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return method;
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}
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}
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}
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return null;
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}
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int getToken(int constant) {
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var method = findNestedTypeMethod(constant);
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if (method == null)
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return 0;
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return method.DeclaringType.MetadataToken.ToInt32();
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}
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int binOp1(int a, int b) {
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return a ^ (b - m1_i1);
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}
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int binOp2(int a, int b) {
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return (a - m2_i1) ^ (b + m2_i2);
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}
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int binOp3(int a, int b) {
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return a ^ (b - m3_i1) ^ (a - b);
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}
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int constMethod1() {
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return binOp3(binOp2(token2, binOp3(token1, token5)), constMethod6());
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}
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int constMethod2() {
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return binOp1(token3, token4 ^ binOp2(token2, binOp3(token6, constMethod4())));
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}
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int constMethod3() {
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return binOp3(binOp1(constMethod2() ^ i1, token4), binOp2(token1 ^ token6, i2));
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}
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int constMethod4() {
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return binOp3(token4, binOp1(token1, binOp2(token2, binOp3(token3, binOp1(token5, token6)))));
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}
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int constMethod5() {
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return binOp2(binOp2(constMethod3(), binOp1(token5, constMethod2())), token6);
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}
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int constMethod6() {
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return binOp1(token6, binOp3(binOp2(token5, token1), binOp3(token3 ^ i3, constMethod5())));
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}
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public ulong getMagic() {
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if (type == null)
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throw new ApplicationException("Can't calculate magic since type isn't initialized");
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var module = type.Module;
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var bytes = new List<byte>();
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if (module.Assembly != null) {
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if (module.Assembly.Name.PublicKeyToken != null)
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bytes.AddRange(module.Assembly.Name.PublicKeyToken);
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bytes.AddRange(Encoding.Unicode.GetBytes(module.Assembly.Name.Name));
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}
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int cm1 = constMethod1();
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bytes.Add((byte)(type.MetadataToken.ToInt32() >> 24));
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bytes.Add((byte)(cm1 >> 16));
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bytes.Add((byte)(type.MetadataToken.ToInt32() >> 8));
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bytes.Add((byte)cm1);
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bytes.Add((byte)(type.MetadataToken.ToInt32() >> 16));
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bytes.Add((byte)(cm1 >> 8));
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bytes.Add((byte)type.MetadataToken.ToInt32());
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bytes.Add((byte)(cm1 >> 24));
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ulong magic = 0;
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foreach (var b in bytes) {
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magic += b;
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magic += magic << 20;
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magic ^= magic >> 12;
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}
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magic += magic << 6;
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magic ^= magic >> 22;
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magic += magic << 30;
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return magic ^ l1;
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}
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}
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}
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