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Find anti-debugger and tamper detection code

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This commit is contained in:
de4dot 2011-10-22 18:13:13 +02:00
parent 1a78c2dc8c
commit 4490c976b3
5 changed files with 154 additions and 2 deletions
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2
de4dot.code/de4dot.code.csproj
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@ -57,11 +57,13 @@
<Compile Include="CommandLineParser.cs" />
<Compile Include="deobfuscators\CliSecure\Deobfuscator.cs" />
<Compile Include="deobfuscators\CliSecure\ProxyDelegateFinder.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\AntiDebugger.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\AssemblyResolver.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\Deobfuscator.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\ResourceDecrypter.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\ResourceResolver.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\StringDecrypter.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\TamperDetection.cs" />
<Compile Include="deobfuscators\DeobfuscatorBase.cs" />
<Compile Include="deobfuscators\DeobfuscatorInfoBase.cs" />
<Compile Include="deobfuscators\DeobUtils.cs" />

75
de4dot.code/deobfuscators/CryptoObfuscator/AntiDebugger.cs Normal file
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@ -0,0 +1,75 @@
/*
Copyright (C) 2011 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 <http://www.gnu.org/licenses/>.
*/
using Mono.Cecil;
using de4dot.blocks;
namespace de4dot.deobfuscators.CryptoObfuscator {
class AntiDebugger {
ModuleDefinition module;
ISimpleDeobfuscator simpleDeobfuscator;
IDeobfuscator deob;
TypeDefinition antiDebuggerType;
MethodDefinition antiDebuggerMethod;
public AntiDebugger(ModuleDefinition module, ISimpleDeobfuscator simpleDeobfuscator, IDeobfuscator deob) {
this.module = module;
this.simpleDeobfuscator = simpleDeobfuscator;
this.deob = deob;
}
public void find() {
var mainMethod = module.EntryPoint;
if (mainMethod == null)
return;
foreach (var info in DotNetUtils.getCalledMethods(module, mainMethod)) {
var type = info.Item1;
var method = info.Item2;
if (!method.IsStatic || !DotNetUtils.isMethod(method, "System.Void", "()"))
continue;
if (DotNetUtils.getPInvokeMethod(type, "kernel32", "LoadLibrary") == null)
continue;
if (DotNetUtils.getPInvokeMethod(type, "kernel32", "GetProcAddress") == null)
continue;
deobfuscate(method);
if (!containsString(method, "debugger was detected"))
continue;
antiDebuggerType = type;
antiDebuggerMethod = method;
return;
}
}
void deobfuscate(MethodDefinition method) {
simpleDeobfuscator.deobfuscate(method);
simpleDeobfuscator.decryptStrings(method, deob);
}
bool containsString(MethodDefinition method, string part) {
foreach (var s in DotNetUtils.getCodeStrings(method)) {
if (s.Contains(part))
return true;
}
return false;
}
}
}

18
de4dot.code/deobfuscators/CryptoObfuscator/Deobfuscator.cs
View File

@ -25,8 +25,11 @@ using de4dot.blocks;
namespace de4dot.deobfuscators.CryptoObfuscator {
class DeobfuscatorInfo : DeobfuscatorInfoBase {
const string DEFAULT_REGEX = @"!^[A-Z]{1,3}(?:`\d+)?$&!^c[0-9a-f]{32}(?:`\d+)?$&" + DeobfuscatorBase.DEFAULT_VALID_NAME_REGEX;
BoolOption removeTamperProtection;
public DeobfuscatorInfo()
: base("co", DEFAULT_REGEX) {
removeTamperProtection = new BoolOption(null, makeArgName("tamper"), "Remove tamper protection code", true);
}
internal static string ObfuscatorType {
@ -40,11 +43,13 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
public override IDeobfuscator createDeobfuscator() {
return new Deobfuscator(new Deobfuscator.Options {
ValidNameRegex = validNameRegex.get(),
RemoveTamperProtection = removeTamperProtection.get(),
});
}
protected override IEnumerable<Option> getOptionsInternal() {
return new List<Option>() {
removeTamperProtection,
};
}
}
@ -59,8 +64,11 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
ResourceResolver resourceResolver;
AssemblyResolver assemblyResolver;
StringDecrypter stringDecrypter;
TamperDetection tamperDetection;
AntiDebugger antiDebugger;
internal class Options : OptionsBase {
public bool RemoveTamperProtection { get; set; }
}
public override string Type {
@ -91,6 +99,8 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
val += 10;
if (stringDecrypter.Detected)
val += 10;
if (tamperDetection.Detected)
val += 10;
return val;
}
@ -107,7 +117,9 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
foundObfuscatedSymbols = true;
stringDecrypter = new StringDecrypter(module);
stringDecrypter.detect();
stringDecrypter.find();
tamperDetection = new TamperDetection(module);
tamperDetection.find();
}
void initializeVersion(TypeDefinition attr) {
@ -153,8 +165,12 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
staticStringDecrypter.add(stringDecrypter.StringDecrypterMethod, (method, args) => {
return stringDecrypter.decrypt((int)args[0]);
});
DeobfuscatedFile.stringDecryptersAdded();
}
antiDebugger = new AntiDebugger(module, DeobfuscatedFile, this);
antiDebugger.find();
dumpEmbeddedAssemblies();
}

2
de4dot.code/deobfuscators/CryptoObfuscator/StringDecrypter.cs
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@ -45,7 +45,7 @@ namespace de4dot.deobfuscators.CryptoObfuscator {
this.module = module;
}
public void detect() {
public void find() {
TypeDefinition type;
MethodDefinition method;
if (!findStringDecrypterType(out type, out method))

59
de4dot.code/deobfuscators/CryptoObfuscator/TamperDetection.cs Normal file
View File

@ -0,0 +1,59 @@
/*
Copyright (C) 2011 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 <http://www.gnu.org/licenses/>.
*/
using Mono.Cecil;
using de4dot.blocks;
namespace de4dot.deobfuscators.CryptoObfuscator {
class TamperDetection {
ModuleDefinition module;
TypeDefinition tamperType;
MethodDefinition tamperMethod;
public bool Detected {
get { return tamperMethod != null; }
}
public TamperDetection(ModuleDefinition module) {
this.module = module;
}
public void find() {
var mainMethod = module.EntryPoint;
if (mainMethod == null)
return;
foreach (var info in DotNetUtils.getCalledMethods(module, mainMethod)) {
var type = info.Item1;
var method = info.Item2;
if (!method.IsStatic || !DotNetUtils.isMethod(method, "System.Void", "()"))
continue;
if (type.Methods.Count != 3)
continue;
if (DotNetUtils.getPInvokeMethod(type, "mscoree", "StrongNameSignatureVerificationEx") == null)
continue;
tamperType = type;
tamperMethod = method;
return;
}
}
}
}