2011-09-22 10:55:30 +08:00
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/*
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Copyright (C) 2011 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.IO;
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using System.Security.Cryptography;
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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.deobfuscators.CliSecure {
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class DeobfuscatorInfo : DeobfuscatorInfoBase {
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const string DEFAULT_REGEX = @"[a-zA-Z_0-9>}$]$";
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BoolOption fixResources;
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BoolOption removeStackFrameHelper;
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public DeobfuscatorInfo()
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: base("cs", DEFAULT_REGEX) {
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fixResources = new BoolOption(null, makeArgName("rsrc"), "Decrypt resources", true);
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removeStackFrameHelper = new BoolOption(null, makeArgName("stack"), "Remove all StackFrameHelper code", true);
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}
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internal static string ObfuscatorType {
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get { return "CliSecure"; }
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}
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public override string Type {
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get { return ObfuscatorType; }
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}
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public override IDeobfuscator createDeobfuscator() {
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return new Deobfuscator(new Deobfuscator.Options {
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ValidNameRegex = validNameRegex.get(),
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FixResources = fixResources.get(),
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RemoveStackFrameHelper = removeStackFrameHelper.get(),
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});
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}
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protected override IEnumerable<Option> getOptionsInternal() {
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return new List<Option>() {
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fixResources,
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removeStackFrameHelper,
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};
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}
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}
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class Deobfuscator : DeobfuscatorBase {
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Options options;
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bool foundCliSecureAttribute = false;
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bool foundProxyDelegateMethod = false;
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MethodDefinition decryptStringMethod;
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byte[] decryptStringBuffer;
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ProxyDelegateFinder proxyDelegateFinder;
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TypeDefinition cliSecureRtType;
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MethodDefinition postInitializeMethod;
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MethodDefinition initializeMethod;
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TypeDefinition stackFrameHelperType;
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ExceptionLoggerRemover exceptionLoggerRemover = new ExceptionLoggerRemover();
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MethodDefinition rsrcRrrMethod;
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MethodDefinition rsrcDecryptMethod;
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internal class Options : OptionsBase {
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public bool FixResources { get; set; }
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public bool RemoveStackFrameHelper { get; set; }
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}
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public override string Type {
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get { return DeobfuscatorInfo.ObfuscatorType; }
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}
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public override string Name {
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get { return Type; }
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}
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public Deobfuscator(Options options)
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: base(options) {
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this.options = options;
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}
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public override void init(ModuleDefinition module, IList<MemberReference> memberReferences) {
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base.init(module, memberReferences);
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proxyDelegateFinder = new ProxyDelegateFinder(module, memberReferences);
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}
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public override int detect() {
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scanForObfuscator();
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int val = 0;
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if (cliSecureRtType != null || foundCliSecureAttribute)
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val += 100;
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if (decryptStringBuffer != null)
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val += 10;
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if (foundProxyDelegateMethod)
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val += 10;
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return val;
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}
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protected override void scanForObfuscatorInternal() {
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findCliSecureAttribute();
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findCliSecureRtType();
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findStringDecryptBuffer();
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findDelegateCreatorType();
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}
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void findCliSecureAttribute() {
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foreach (var type in module.Types) {
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if (type.FullName == "SecureTeam.Attributes.ObfuscatedByCliSecureAttribute") {
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this.addAttributeToBeRemoved(type, "Obfuscator attribute");
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foundCliSecureAttribute = true;
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break;
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}
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}
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}
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void findCliSecureRtType() {
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if (cliSecureRtType != null)
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return;
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foreach (var type in module.Types) {
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if (type.Namespace != "")
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continue;
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var typeName = type.FullName;
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MethodDefinition cs = null;
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MethodDefinition initialize = null;
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MethodDefinition postInitialize = null;
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MethodDefinition load = null;
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int methods = 0;
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foreach (var method in type.Methods) {
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if (method.FullName == "System.String " + typeName + "::cs(System.String)") {
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cs = method;
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methods++;
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}
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else if (method.FullName == "System.Void " + typeName + "::Initialize()") {
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initialize = method;
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methods++;
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}
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else if (method.FullName == "System.Void " + typeName + "::PostInitialize()") {
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postInitialize = method;
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methods++;
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}
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else if (method.FullName == "System.IntPtr " + typeName + "::Load()") {
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load = method;
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methods++;
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}
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}
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if (methods < 2)
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continue;
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decryptStringMethod = cs;
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initializeMethod = initialize;
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postInitializeMethod = postInitialize;
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cliSecureRtType = type;
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if (load != null)
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findPossibleNamesToRemove(load);
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return;
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}
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}
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void findStringDecryptBuffer() {
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foreach (var type in module.Types) {
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if (type.FullName == "<D234>" || type.FullName == "<ClassD234>") {
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addTypeToBeRemoved(type, "Obfuscator string decrypter type");
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foreach (var field in type.Fields) {
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if (field.FullName == "<D234> <D234>::345" || field.FullName == "<ClassD234>/D234 <ClassD234>::345") {
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decryptStringBuffer = field.InitialValue;
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break;
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}
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}
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break;
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}
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}
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}
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void findDelegateCreatorType() {
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foreach (var type in module.Types) {
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var methodName = "System.Void " + type.FullName + "::icgd(System.Int32)";
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foreach (var method in type.Methods) {
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if (method.FullName == methodName) {
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proxyDelegateFinder.setDelegateCreatorMethod(method);
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foundProxyDelegateMethod = true;
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return;
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}
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}
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}
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}
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public override void deobfuscateBegin() {
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base.deobfuscateBegin();
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foreach (var type in module.Types) {
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if (type.FullName == "InitializeDelegate" && DotNetUtils.isDelegateType(type))
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this.addTypeToBeRemoved(type, "Obfuscator type");
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else if (findResourceDecrypter(type)) {
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// Nothing
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}
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if (options.RemoveStackFrameHelper)
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findStackFrameHelper(type);
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}
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proxyDelegateFinder.find();
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if (decryptStringMethod != null)
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staticStringDecrypter.add(decryptStringMethod, (method, args) => decryptString((string)args[0]));
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addCctorInitCallToBeRemoved(initializeMethod);
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addCctorInitCallToBeRemoved(postInitializeMethod);
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if (options.FixResources)
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addCctorInitCallToBeRemoved(rsrcRrrMethod);
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}
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bool findResourceDecrypter(TypeDefinition type) {
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MethodDefinition rrrMethod = null;
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MethodDefinition decryptMethod = null;
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foreach (var method in type.Methods) {
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if (method.Name == "rrr" && DotNetUtils.isMethod(method, "System.Void", "()"))
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rrrMethod = method;
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else if (DotNetUtils.isMethod(method, "System.Reflection.Assembly", "(System.Object,System.ResolveEventArgs)"))
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decryptMethod = method;
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}
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if (rrrMethod == null || decryptMethod == null)
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return false;
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var methodCalls = DotNetUtils.getMethodCallCounts(rrrMethod);
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if (methodCalls.count("System.Void System.ResolveEventHandler::.ctor(System.Object,System.IntPtr)") != 1)
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return false;
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rsrcRrrMethod = rrrMethod;
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rsrcDecryptMethod = decryptMethod;
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return true;
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}
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void decryptResources() {
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if (rsrcDecryptMethod == null)
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return;
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var resource = getResource(DotNetUtils.getCodeStrings(rsrcDecryptMethod)) as EmbeddedResource;
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if (resource == null)
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return;
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2011-09-24 16:26:29 +08:00
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DeobUtils.decryptAndAddResources(module, resource.Name, () => decryptResource(resource));
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2011-09-22 10:55:30 +08:00
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addResourceToBeRemoved(resource, "Encrypted resource");
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if (rsrcDecryptMethod != null)
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addTypeToBeRemoved(rsrcDecryptMethod.DeclaringType, "Obfuscator resource decrypter type");
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}
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byte[] decryptResource(EmbeddedResource resource) {
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using (var rsrcStream = resource.GetResourceStream()) {
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using (var reader = new BinaryReader(rsrcStream)) {
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var key = reader.ReadString();
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var data = reader.ReadBytes((int)(rsrcStream.Length - rsrcStream.Position));
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var cryptoTransform = new DESCryptoServiceProvider {
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Key = Encoding.ASCII.GetBytes(key),
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IV = Encoding.ASCII.GetBytes(key),
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}.CreateDecryptor();
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var memStream = new MemoryStream(data);
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using (var reader2 = new BinaryReader(new CryptoStream(memStream, cryptoTransform, CryptoStreamMode.Read))) {
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return reader2.ReadBytes((int)memStream.Length);
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}
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}
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}
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}
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void findStackFrameHelper(TypeDefinition type) {
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if (!type.HasMethods)
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return;
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if (type.Methods.Count > 3)
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return;
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MethodDefinition errorMethod = null;
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foreach (var method in type.Methods) {
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if (method.IsRuntimeSpecialName && method.Name == ".ctor" && method.HasParameters == false)
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continue; // .ctor is allowed
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if (method.IsRuntimeSpecialName && method.Name == ".cctor" && method.HasParameters == false)
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continue; // .cctor is allowed
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if (method.IsStatic && method.CallingConvention == MethodCallingConvention.Default &&
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method.ExplicitThis == false && method.HasThis == false &&
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method.HasBody && method.IsManaged && method.IsIL && method.HasParameters &&
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method.Parameters.Count == 2 && method.HasGenericParameters == false &&
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!DotNetUtils.hasReturnValue(method) &&
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MemberReferenceHelper.verifyType(method.Parameters[0].ParameterType, "mscorlib", "System.Exception") &&
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MemberReferenceHelper.verifyType(method.Parameters[1].ParameterType, "mscorlib", "System.Object", "[]")) {
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errorMethod = method;
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}
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else
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return;
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}
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if (errorMethod != null) {
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if (stackFrameHelperType != null)
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throw new ApplicationException("Found another StackFrameHelper");
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stackFrameHelperType = type;
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exceptionLoggerRemover.add(errorMethod);
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}
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}
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public override void deobfuscateMethodEnd(Blocks blocks) {
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proxyDelegateFinder.deobfuscate(blocks);
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removeStackFrameHelperCode(blocks);
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base.deobfuscateMethodEnd(blocks);
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}
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public override void deobfuscateEnd() {
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if (options.FixResources)
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decryptResources();
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removeProxyDelegates(proxyDelegateFinder);
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if (exceptionLoggerRemover.NumRemovedExceptionLoggers > 0)
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addTypeToBeRemoved(stackFrameHelperType, "StackFrameHelper type");
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if (Operations.DecryptStrings != OpDecryptString.None)
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addTypeToBeRemoved(cliSecureRtType, "Obfuscator type");
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addResources("Obfuscator protection files");
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addModuleReferences("Obfuscator protection files");
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base.deobfuscateEnd();
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}
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public override IEnumerable<string> getStringDecrypterMethods() {
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var list = new List<string>();
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if (decryptStringMethod != null)
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list.Add(decryptStringMethod.MetadataToken.ToInt32().ToString("X8"));
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return list;
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}
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string decryptString(string es) {
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if (decryptStringBuffer == null)
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throw new ApplicationException("Trying to decrypt strings when decryptStringBuffer is null (could not find it!)");
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StringBuilder sb = new StringBuilder(es.Length);
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for (int i = 0; i < es.Length; i++)
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sb.Append(Convert.ToChar((int)(es[i] ^ decryptStringBuffer[i % decryptStringBuffer.Length])));
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return sb.ToString();
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}
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void removeStackFrameHelperCode(Blocks blocks) {
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if (exceptionLoggerRemover.remove(blocks))
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Log.v("Removed StackFrameHelper code");
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}
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}
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}
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