275 lines
9.4 KiB
C#
275 lines
9.4 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.RegularExpressions;
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using Mono.Cecil;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.CryptoObfuscator {
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public class DeobfuscatorInfo : DeobfuscatorInfoBase {
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public const string THE_NAME = "Crypto Obfuscator";
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public const string THE_TYPE = "co";
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const string DEFAULT_REGEX = @"!^(get_|set_|add_|remove_)?[A-Z]{1,3}(?:`\d+)?$&!^(get_|set_|add_|remove_)?c[0-9a-f]{32}(?:`\d+)?$&" + DeobfuscatorBase.DEFAULT_VALID_NAME_REGEX;
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BoolOption removeTamperProtection;
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BoolOption decryptConstants;
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public DeobfuscatorInfo()
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: base(DEFAULT_REGEX) {
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removeTamperProtection = new BoolOption(null, makeArgName("tamper"), "Remove tamper protection code", true);
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decryptConstants = new BoolOption(null, makeArgName("consts"), "Decrypt constants", true);
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}
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public override string Name {
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get { return THE_NAME; }
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}
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public override string Type {
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get { return THE_TYPE; }
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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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RemoveTamperProtection = removeTamperProtection.get(),
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DecryptConstants = decryptConstants.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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removeTamperProtection,
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decryptConstants,
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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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string obfuscatorName = DeobfuscatorInfo.THE_NAME;
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bool foundCryptoObfuscatorAttribute = false;
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bool foundObfuscatedSymbols = false;
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bool foundObfuscatorUserString = false;
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ProxyDelegateFinder proxyDelegateFinder;
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ResourceDecrypter resourceDecrypter;
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ResourceResolver resourceResolver;
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AssemblyResolver assemblyResolver;
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StringDecrypter stringDecrypter;
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TamperDetection tamperDetection;
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AntiDebugger antiDebugger;
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ConstantsDecrypter constantsDecrypter;
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Int32ValueInliner int32ValueInliner;
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Int64ValueInliner int64ValueInliner;
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SingleValueInliner singleValueInliner;
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DoubleValueInliner doubleValueInliner;
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internal class Options : OptionsBase {
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public bool RemoveTamperProtection { get; set; }
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public bool DecryptConstants { get; set; }
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}
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public override string Type {
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get { return DeobfuscatorInfo.THE_TYPE; }
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}
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public override string TypeLong {
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get { return DeobfuscatorInfo.THE_NAME; }
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}
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public override string Name {
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get { return obfuscatorName; }
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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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StringFeatures = StringFeatures.AllowStaticDecryption | StringFeatures.AllowDynamicDecryption;
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}
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public override void init(ModuleDefinition module) {
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base.init(module);
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}
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protected override int detectInternal() {
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int val = 0;
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int sum = toInt32(stringDecrypter.Detected) +
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toInt32(tamperDetection.Detected) +
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toInt32(proxyDelegateFinder.Detected) +
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toInt32(constantsDecrypter.Detected);
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if (sum > 0)
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val += 100 + 10 * (sum - 1);
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if (foundCryptoObfuscatorAttribute || foundObfuscatedSymbols || foundObfuscatorUserString)
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val += 10;
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return val;
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}
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protected override void scanForObfuscator() {
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foreach (var type in module.Types) {
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if (type.FullName == "CryptoObfuscator.ProtectedWithCryptoObfuscatorAttribute") {
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foundCryptoObfuscatorAttribute = true;
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addAttributeToBeRemoved(type, "Obfuscator attribute");
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initializeVersion(type);
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}
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}
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if (checkCryptoObfuscator())
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foundObfuscatedSymbols = true;
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proxyDelegateFinder = new ProxyDelegateFinder(module);
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proxyDelegateFinder.findDelegateCreator();
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stringDecrypter = new StringDecrypter(module);
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stringDecrypter.find();
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tamperDetection = new TamperDetection(module);
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tamperDetection.find();
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constantsDecrypter = new ConstantsDecrypter(module);
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constantsDecrypter.find();
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foundObfuscatorUserString = Utils.StartsWith(module.GetUserString(1), "\u0011\"3D9B94A98B-76A8-4810-B1A0-4BE7C4F9C98D", StringComparison.Ordinal);
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}
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void initializeVersion(TypeDefinition attr) {
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var s = DotNetUtils.getCustomArgAsString(getAssemblyAttribute(attr), 0);
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if (s == null)
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return;
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var val = Regex.Match(s, @"^Protected with (Crypto Obfuscator.*)$");
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if (val.Groups.Count < 2)
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return;
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obfuscatorName = val.Groups[1].ToString();
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return;
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}
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bool checkCryptoObfuscator() {
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int matched = 0;
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foreach (var type in module.Types) {
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if (type.Namespace != "A")
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continue;
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if (Regex.IsMatch(type.Name, "^c[0-9a-f]{32}$"))
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return true;
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else if (Regex.IsMatch(type.Name, "^A[A-Z]*$")) {
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if (++matched >= 10)
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return true;
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}
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}
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return false;
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}
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public override void deobfuscateBegin() {
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base.deobfuscateBegin();
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resourceDecrypter = new ResourceDecrypter(module, DeobfuscatedFile);
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resourceResolver = new ResourceResolver(module, resourceDecrypter);
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assemblyResolver = new AssemblyResolver(module);
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resourceResolver.find();
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assemblyResolver.find();
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decryptResources();
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stringDecrypter.init(resourceDecrypter);
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if (stringDecrypter.Method != null) {
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staticStringInliner.add(stringDecrypter.Method, (method, args) => {
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return stringDecrypter.decrypt((int)args[0]);
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});
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DeobfuscatedFile.stringDecryptersAdded();
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}
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antiDebugger = new AntiDebugger(module, DeobfuscatedFile, this);
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antiDebugger.find();
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if (options.DecryptConstants) {
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constantsDecrypter.init(resourceDecrypter);
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int32ValueInliner = new Int32ValueInliner();
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int32ValueInliner.add(constantsDecrypter.Int32Decrypter, (method, args) => constantsDecrypter.decryptInt32((int)args[0]));
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int64ValueInliner = new Int64ValueInliner();
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int64ValueInliner.add(constantsDecrypter.Int64Decrypter, (method, args) => constantsDecrypter.decryptInt64((int)args[0]));
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singleValueInliner = new SingleValueInliner();
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singleValueInliner.add(constantsDecrypter.SingleDecrypter, (method, args) => constantsDecrypter.decryptSingle((int)args[0]));
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doubleValueInliner = new DoubleValueInliner();
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doubleValueInliner.add(constantsDecrypter.DoubleDecrypter, (method, args) => constantsDecrypter.decryptDouble((int)args[0]));
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addTypeToBeRemoved(constantsDecrypter.Type, "Constants decrypter type");
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addResourceToBeRemoved(constantsDecrypter.Resource, "Encrypted constants");
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}
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addModuleCctorInitCallToBeRemoved(resourceResolver.Method);
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addModuleCctorInitCallToBeRemoved(assemblyResolver.Method);
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addCallToBeRemoved(module.EntryPoint, tamperDetection.Method);
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addModuleCctorInitCallToBeRemoved(tamperDetection.Method);
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addCallToBeRemoved(module.EntryPoint, antiDebugger.Method);
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addModuleCctorInitCallToBeRemoved(antiDebugger.Method);
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addTypeToBeRemoved(resourceResolver.Type, "Resource resolver type");
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addTypeToBeRemoved(assemblyResolver.Type, "Assembly resolver type");
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addTypeToBeRemoved(tamperDetection.Type, "Tamper detection type");
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addTypeToBeRemoved(antiDebugger.Type, "Anti-debugger type");
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proxyDelegateFinder.find();
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dumpEmbeddedAssemblies();
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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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if (options.DecryptConstants) {
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int32ValueInliner.decrypt(blocks);
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int64ValueInliner.decrypt(blocks);
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singleValueInliner.decrypt(blocks);
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doubleValueInliner.decrypt(blocks);
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}
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base.deobfuscateMethodEnd(blocks);
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}
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public override void deobfuscateEnd() {
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removeProxyDelegates(proxyDelegateFinder);
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if (CanRemoveStringDecrypterType) {
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addResourceToBeRemoved(stringDecrypter.Resource, "Encrypted strings");
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addTypeToBeRemoved(stringDecrypter.Type, "String decrypter type");
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}
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base.deobfuscateEnd();
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}
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void decryptResources() {
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var rsrc = resourceResolver.mergeResources();
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if (rsrc == null)
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return;
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addResourceToBeRemoved(rsrc, "Encrypted resources");
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}
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void dumpEmbeddedAssemblies() {
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foreach (var info in assemblyResolver.AssemblyInfos) {
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dumpEmbeddedFile(info.resource, info.assemblyName, ".dll", string.Format("Embedded assembly: {0}", info.assemblyName));
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if (info.symbolsResource != null)
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dumpEmbeddedFile(info.symbolsResource, info.assemblyName, ".pdb", string.Format("Embedded pdb: {0}", info.assemblyName));
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}
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}
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void dumpEmbeddedFile(EmbeddedResource resource, string assemblyName, string extension, string reason) {
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DeobfuscatedFile.createAssemblyFile(resourceDecrypter.decrypt(resource.GetResourceStream()), Utils.getAssemblySimpleName(assemblyName), extension);
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addResourceToBeRemoved(resource, reason);
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}
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public override IEnumerable<int> getStringDecrypterMethods() {
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var list = new List<int>();
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if (stringDecrypter.Method != null)
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list.Add(stringDecrypter.Method.MetadataToken.ToInt32());
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return list;
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}
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}
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}
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