368 lines
9.8 KiB
C#
368 lines
9.8 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 dot10.DotNet;
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using dot10.DotNet.Emit;
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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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ModuleDefinition module;
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ISimpleDeobfuscator simpleDeobfuscator;
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TypeDef type;
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MethodDef 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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MethodDef[] efConstMethods;
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public TypeDef 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 DecrypterType(ModuleDefinition module, ISimpleDeobfuscator simpleDeobfuscator) {
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this.module = module;
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this.simpleDeobfuscator = simpleDeobfuscator;
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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 (!initializeEfConstMethods())
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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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initialized = true;
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return true;
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}
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bool initializeEfConstMethods() {
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if (type == null)
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return false;
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efConstMethods = new MethodDef[6];
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efConstMethods[0] = findEfConstMethodCall(int64Method);
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efConstMethods[5] = findEfConstMethodCall(efConstMethods[0]);
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efConstMethods[4] = findEfConstMethodCall(efConstMethods[5]);
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var calls = findEfConstMethodCalls(efConstMethods[4]);
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if (calls.Count != 2)
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return false;
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if (getNumberOfTypeofs(calls[0]) == 3) {
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efConstMethods[2] = calls[0];
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efConstMethods[1] = calls[1];
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}
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else {
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efConstMethods[2] = calls[0];
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efConstMethods[1] = calls[1];
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}
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efConstMethods[3] = findEfConstMethodCall(efConstMethods[1]);
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foreach (var m in efConstMethods) {
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if (m == null)
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return false;
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}
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return true;
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}
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static int getNumberOfTypeofs(MethodDef method) {
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if (method == null)
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return 0;
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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.Ldtoken)
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count++;
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}
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return count;
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}
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MethodDef findEfConstMethodCall(MethodDef method) {
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var list = findEfConstMethodCalls(method);
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if (list == null || list.Count != 1)
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return null;
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return list[0];
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}
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List<MethodDef> findEfConstMethodCalls(MethodDef method) {
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if (method == null)
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return null;
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var list = new List<MethodDef>();
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code != Code.Call)
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continue;
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var calledMethod = instr.Operand as MethodDef;
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if (calledMethod == null || !calledMethod.IsStatic || calledMethod.Body == null)
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continue;
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if (!DotNetUtils.isMethod(calledMethod, "System.Int32", "()"))
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continue;
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if (type.NestedTypes.IndexOf(calledMethod.DeclaringType) < 0)
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continue;
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list.Add(calledMethod);
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}
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return list;
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}
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MethodDef 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(MethodDef 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(efConstMethods[2]);
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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(efConstMethods[5]);
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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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foreach (var m in methods)
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simpleDeobfuscator.deobfuscate(m);
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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<MethodDef> getBinaryIntMethods(TypeDef type) {
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var list = new List<MethodDef>();
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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<MethodDef> 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<MethodDef> 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<MethodDef> 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(MethodDef 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(MethodDef 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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var constantsReader = new EfConstantsReader(method);
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while (true) {
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int val;
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if (!constantsReader.getNextInt32(ref index, out val))
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break;
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if (index < 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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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(efConstMethods[1].DeclaringType.MDToken.ToInt32(), binOp3(efConstMethods[0].DeclaringType.MDToken.ToInt32(), efConstMethods[4].DeclaringType.MDToken.ToInt32())), constMethod6());
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}
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int constMethod2() {
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return binOp1(efConstMethods[2].DeclaringType.MDToken.ToInt32(), efConstMethods[3].DeclaringType.MDToken.ToInt32() ^ binOp2(efConstMethods[1].DeclaringType.MDToken.ToInt32(), binOp3(efConstMethods[5].DeclaringType.MDToken.ToInt32(), constMethod4())));
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}
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int constMethod3() {
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return binOp3(binOp1(constMethod2() ^ i1, efConstMethods[3].DeclaringType.MDToken.ToInt32()), binOp2(efConstMethods[0].DeclaringType.MDToken.ToInt32() ^ efConstMethods[5].DeclaringType.MDToken.ToInt32(), i2));
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}
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int constMethod4() {
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return binOp3(efConstMethods[3].DeclaringType.MDToken.ToInt32(), binOp1(efConstMethods[0].DeclaringType.MDToken.ToInt32(), binOp2(efConstMethods[1].DeclaringType.MDToken.ToInt32(), binOp3(efConstMethods[2].DeclaringType.MDToken.ToInt32(), binOp1(efConstMethods[4].DeclaringType.MDToken.ToInt32(), efConstMethods[5].DeclaringType.MDToken.ToInt32())))));
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}
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int constMethod5() {
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return binOp2(binOp2(constMethod3(), binOp1(efConstMethods[4].DeclaringType.MDToken.ToInt32(), constMethod2())), efConstMethods[5].DeclaringType.MDToken.ToInt32());
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}
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int constMethod6() {
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return binOp1(efConstMethods[5].DeclaringType.MDToken.ToInt32(), binOp3(binOp2(efConstMethods[4].DeclaringType.MDToken.ToInt32(), efConstMethods[0].DeclaringType.MDToken.ToInt32()), binOp3(efConstMethods[2].DeclaringType.MDToken.ToInt32() ^ 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 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.MDToken.ToInt32() >> 24));
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bytes.Add((byte)(cm1 >> 16));
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bytes.Add((byte)(type.MDToken.ToInt32() >> 8));
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bytes.Add((byte)cm1);
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bytes.Add((byte)(type.MDToken.ToInt32() >> 16));
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bytes.Add((byte)(cm1 >> 8));
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bytes.Add((byte)type.MDToken.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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