/*
Copyright (C) 2011-2014 de4dot@gmail.com
This file is part of de4dot.
de4dot is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
de4dot is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with de4dot. If not, see .
*/
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using dnlib.DotNet;
using de4dot.blocks;
using de4dot.blocks.cflow;
namespace de4dot.code.deobfuscators.CryptoObfuscator {
public class DeobfuscatorInfo : DeobfuscatorInfoBase {
public const string THE_NAME = "Crypto Obfuscator";
public const string THE_TYPE = "co";
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_ASIAN_VALID_NAME_REGEX;
BoolOption removeTamperProtection;
BoolOption decryptConstants;
BoolOption inlineMethods;
BoolOption fixLdnull;
public DeobfuscatorInfo()
: base(DEFAULT_REGEX) {
removeTamperProtection = new BoolOption(null, MakeArgName("tamper"), "Remove tamper protection code", true);
decryptConstants = new BoolOption(null, MakeArgName("consts"), "Decrypt constants", true);
inlineMethods = new BoolOption(null, MakeArgName("inline"), "Inline short methods", true);
fixLdnull = new BoolOption(null, MakeArgName("ldnull"), "Restore ldnull instructions", true);
}
public override string Name {
get { return THE_NAME; }
}
public override string Type {
get { return THE_TYPE; }
}
public override IDeobfuscator CreateDeobfuscator() {
return new Deobfuscator(new Deobfuscator.Options {
ValidNameRegex = validNameRegex.Get(),
RemoveTamperProtection = removeTamperProtection.Get(),
DecryptConstants = decryptConstants.Get(),
InlineMethods = inlineMethods.Get(),
FixLdnull = fixLdnull.Get(),
});
}
protected override IEnumerable GetOptionsInternal() {
return new List () {
removeTamperProtection,
decryptConstants,
inlineMethods,
fixLdnull,
};
}
}
class Deobfuscator : DeobfuscatorBase {
Options options;
string obfuscatorName = DeobfuscatorInfo.THE_NAME;
bool foundCryptoObfuscatorAttribute = false;
bool foundObfuscatedSymbols = false;
bool foundObfuscatorUserString = false;
bool startedDeobfuscating = false;
MethodsDecrypter methodsDecrypter;
ProxyCallFixer proxyCallFixer;
ResourceDecrypter resourceDecrypter;
ResourceResolver resourceResolver;
AssemblyResolver assemblyResolver;
StringDecrypter stringDecrypter;
TamperDetection tamperDetection;
AntiDebugger antiDebugger;
ConstantsDecrypter constantsDecrypter;
Int32ValueInliner int32ValueInliner;
Int64ValueInliner int64ValueInliner;
SingleValueInliner singleValueInliner;
DoubleValueInliner doubleValueInliner;
InlinedMethodTypes inlinedMethodTypes;
internal class Options : OptionsBase {
public bool RemoveTamperProtection { get; set; }
public bool DecryptConstants { get; set; }
public bool InlineMethods { get; set; }
public bool FixLdnull { get; set; }
}
public override string Type {
get { return DeobfuscatorInfo.THE_TYPE; }
}
public override string TypeLong {
get { return DeobfuscatorInfo.THE_NAME; }
}
public override string Name {
get { return obfuscatorName; }
}
protected override bool CanInlineMethods {
get { return startedDeobfuscating ? options.InlineMethods : true; }
}
public override IEnumerable BlocksDeobfuscators {
get {
var list = new List();
if (CanInlineMethods)
list.Add(new CoMethodCallInliner(inlinedMethodTypes));
return list;
}
}
public Deobfuscator(Options options)
: base(options) {
this.options = options;
StringFeatures = StringFeatures.AllowStaticDecryption | StringFeatures.AllowDynamicDecryption;
}
public override void Initialize(ModuleDefMD module) {
base.Initialize(module);
}
protected override int DetectInternal() {
int val = 0;
int sum = ToInt32(methodsDecrypter.Detected) +
ToInt32(stringDecrypter.Detected) +
ToInt32(tamperDetection.Detected) +
ToInt32(proxyCallFixer.Detected) +
ToInt32(constantsDecrypter.Detected);
if (sum > 0)
val += 100 + 10 * (sum - 1);
if (foundCryptoObfuscatorAttribute || foundObfuscatedSymbols || foundObfuscatorUserString)
val += 10;
return val;
}
protected override void ScanForObfuscator() {
foreach (var type in module.Types) {
if (type.FullName == "CryptoObfuscator.ProtectedWithCryptoObfuscatorAttribute") {
foundCryptoObfuscatorAttribute = true;
AddAttributeToBeRemoved(type, "Obfuscator attribute");
InitializeVersion(type);
}
}
if (CheckCryptoObfuscator())
foundObfuscatedSymbols = true;
inlinedMethodTypes = new InlinedMethodTypes();
methodsDecrypter = new MethodsDecrypter(module);
methodsDecrypter.Find();
proxyCallFixer = new ProxyCallFixer(module);
proxyCallFixer.FindDelegateCreator();
stringDecrypter = new StringDecrypter(module);
stringDecrypter.Find();
tamperDetection = new TamperDetection(module);
tamperDetection.Find();
constantsDecrypter = new ConstantsDecrypter(module, initializedDataCreator);
constantsDecrypter.Find();
foundObfuscatorUserString = Utils.StartsWith(module.ReadUserString(0x70000001), "\u0011\"3D9B94A98B-76A8-4810-B1A0-4BE7C4F9C98D", StringComparison.Ordinal);
}
void InitializeVersion(TypeDef attr) {
var s = DotNetUtils.GetCustomArgAsString(GetAssemblyAttribute(attr), 0);
if (s == null)
return;
var val = Regex.Match(s, @"^Protected with (Crypto Obfuscator.*)$");
if (val.Groups.Count < 2)
return;
obfuscatorName = val.Groups[1].ToString();
return;
}
bool CheckCryptoObfuscator() {
int matched = 0;
foreach (var type in module.Types) {
if (type.Namespace != "A")
continue;
if (Regex.IsMatch(type.Name.String, "^c[0-9a-f]{32}$"))
return true;
else if (Regex.IsMatch(type.Name.String, "^A[A-Z]*$")) {
if (++matched >= 10)
return true;
}
}
return false;
}
public override void DeobfuscateBegin() {
base.DeobfuscateBegin();
resourceDecrypter = new ResourceDecrypter(module, DeobfuscatedFile);
resourceResolver = new ResourceResolver(module, resourceDecrypter);
assemblyResolver = new AssemblyResolver(module);
resourceResolver.Find();
assemblyResolver.Find(DeobfuscatedFile);
DecryptResources();
stringDecrypter.Initialize(resourceDecrypter);
if (stringDecrypter.Method != null) {
staticStringInliner.Add(stringDecrypter.Method, (method, gim, args) => {
return stringDecrypter.Decrypt((int)args[0]);
});
DeobfuscatedFile.StringDecryptersAdded();
}
methodsDecrypter.Decrypt(resourceDecrypter, DeobfuscatedFile);
if (methodsDecrypter.Detected) {
if (!assemblyResolver.Detected)
assemblyResolver.Find(DeobfuscatedFile);
if (!tamperDetection.Detected)
tamperDetection.Find();
}
antiDebugger = new AntiDebugger(module, DeobfuscatedFile, this);
antiDebugger.Find();
if (options.DecryptConstants) {
constantsDecrypter.Initialize(resourceDecrypter);
int32ValueInliner = new Int32ValueInliner();
int32ValueInliner.Add(constantsDecrypter.Int32Decrypter, (method, gim, args) => constantsDecrypter.DecryptInt32((int)args[0]));
int64ValueInliner = new Int64ValueInliner();
int64ValueInliner.Add(constantsDecrypter.Int64Decrypter, (method, gim, args) => constantsDecrypter.DecryptInt64((int)args[0]));
singleValueInliner = new SingleValueInliner();
singleValueInliner.Add(constantsDecrypter.SingleDecrypter, (method, gim, args) => constantsDecrypter.DecryptSingle((int)args[0]));
doubleValueInliner = new DoubleValueInliner();
doubleValueInliner.Add(constantsDecrypter.DoubleDecrypter, (method, gim, args) => constantsDecrypter.DecryptDouble((int)args[0]));
AddTypeToBeRemoved(constantsDecrypter.Type, "Constants decrypter type");
AddResourceToBeRemoved(constantsDecrypter.Resource, "Encrypted constants");
}
AddModuleCctorInitCallToBeRemoved(resourceResolver.Method);
AddModuleCctorInitCallToBeRemoved(assemblyResolver.Method);
AddCallToBeRemoved(module.EntryPoint, tamperDetection.Method);
AddModuleCctorInitCallToBeRemoved(tamperDetection.Method);
AddCallToBeRemoved(module.EntryPoint, antiDebugger.Method);
AddModuleCctorInitCallToBeRemoved(antiDebugger.Method);
AddTypeToBeRemoved(resourceResolver.Type, "Resource resolver type");
AddTypeToBeRemoved(assemblyResolver.Type, "Assembly resolver type");
AddTypeToBeRemoved(tamperDetection.Type, "Tamper detection type");
AddTypeToBeRemoved(antiDebugger.Type, "Anti-debugger type");
AddTypeToBeRemoved(methodsDecrypter.Type, "Methods decrypter type");
AddTypesToBeRemoved(methodsDecrypter.DelegateTypes, "Methods decrypter delegate type");
AddResourceToBeRemoved(methodsDecrypter.Resource, "Encrypted methods");
proxyCallFixer.Find();
DumpEmbeddedAssemblies();
startedDeobfuscating = true;
}
public override void DeobfuscateMethodEnd(Blocks blocks) {
proxyCallFixer.Deobfuscate(blocks);
if (options.DecryptConstants) {
int32ValueInliner.Decrypt(blocks);
int64ValueInliner.Decrypt(blocks);
singleValueInliner.Decrypt(blocks);
doubleValueInliner.Decrypt(blocks);
constantsDecrypter.Deobfuscate(blocks);
}
base.DeobfuscateMethodEnd(blocks);
}
public override void DeobfuscateEnd() {
if (options.FixLdnull)
new LdnullFixer(module, inlinedMethodTypes).Restore();
RemoveProxyDelegates(proxyCallFixer);
if (CanRemoveStringDecrypterType) {
AddResourceToBeRemoved(stringDecrypter.Resource, "Encrypted strings");
AddTypeToBeRemoved(stringDecrypter.Type, "String decrypter type");
}
AddTypesToBeRemoved(inlinedMethodTypes.Types, "Inlined methods type");
base.DeobfuscateEnd();
}
void DecryptResources() {
var rsrc = resourceResolver.MergeResources();
if (rsrc == null)
return;
AddResourceToBeRemoved(rsrc, "Encrypted resources");
}
void DumpEmbeddedAssemblies() {
foreach (var info in assemblyResolver.AssemblyInfos) {
DumpEmbeddedFile(info.resource, info.assemblyName, ".dll", string.Format("Embedded assembly: {0}", info.assemblyName));
if (info.symbolsResource != null)
DumpEmbeddedFile(info.symbolsResource, info.assemblyName, ".pdb", string.Format("Embedded pdb: {0}", info.assemblyName));
}
}
void DumpEmbeddedFile(EmbeddedResource resource, string assemblyName, string extension, string reason) {
DeobfuscatedFile.CreateAssemblyFile(resourceDecrypter.Decrypt(resource.GetResourceStream()), Utils.GetAssemblySimpleName(assemblyName), extension);
AddResourceToBeRemoved(resource, reason);
}
public override IEnumerable GetStringDecrypterMethods() {
var list = new List();
if (stringDecrypter.Method != null)
list.Add(stringDecrypter.Method.MDToken.ToInt32());
return list;
}
}
}