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Decrypt strings

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This commit is contained in:
de4dot 2011-10-26 19:49:25 +02:00
parent 03a8372319
commit f37a46a02b
6 changed files with 277 additions and 52 deletions
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1
de4dot.code/de4dot.code.csproj
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@ -73,6 +73,7 @@
<Compile Include="deobfuscators\dotNET_Reactor\EncryptedResource.cs" />
<Compile Include="deobfuscators\dotNET_Reactor\LocalTypes.cs" />
<Compile Include="deobfuscators\dotNET_Reactor\MethodsDecrypter.cs" />
<Compile Include="deobfuscators\dotNET_Reactor\StringDecrypter.cs" />
<Compile Include="deobfuscators\Eazfuscator\Deobfuscator.cs" />
<Compile Include="deobfuscators\ExceptionLoggerRemover.cs" />
<Compile Include="deobfuscators\IDeobfuscatedFile.cs" />

36
de4dot.code/deobfuscators/dotNET_Reactor/Deobfuscator.cs
View File

@ -17,6 +17,7 @@
along with de4dot. If not, see <http://www.gnu.org/licenses/>.
*/
using System.IO;
using System.Collections.Generic;
using Mono.Cecil;
using de4dot.blocks;
@ -50,7 +51,10 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
class Deobfuscator : DeobfuscatorBase {
Options options;
PE.PeImage peImage;
byte[] fileData;
MethodsDecrypter methodsDecrypter;
StringDecrypter stringDecrypter;
internal class Options : OptionsBase {
}
@ -76,7 +80,11 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
int val = 0;
if (methodsDecrypter.Detected)
val = 100;
val += 100;
else if (stringDecrypter.Detected)
val += 100;
if (methodsDecrypter.Detected && stringDecrypter.Detected)
val += 10;
return val;
}
@ -84,21 +92,43 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
protected override void scanForObfuscator() {
methodsDecrypter = new MethodsDecrypter(module);
methodsDecrypter.find();
stringDecrypter = new StringDecrypter(module);
stringDecrypter.find();
}
public override byte[] getDecryptedModule() {
return methodsDecrypter.decrypt(DeobfuscatedFile);
using (var fileStream = new FileStream(module.FullyQualifiedName, FileMode.Open, FileAccess.Read, FileShare.Read)) {
fileData = new byte[(int)fileStream.Length];
fileStream.Read(fileData, 0, fileData.Length);
}
peImage = new PE.PeImage(fileData);
if (!methodsDecrypter.decrypt(peImage, DeobfuscatedFile))
return null;
return fileData;
}
public override IDeobfuscator moduleReloaded(ModuleDefinition module) {
var newOne = new Deobfuscator(options);
newOne.setModule(module);
newOne.peImage = new PE.PeImage(fileData);
newOne.methodsDecrypter = new MethodsDecrypter(module, methodsDecrypter);
newOne.stringDecrypter = new StringDecrypter(module, stringDecrypter);
return newOne;
}
public override void deobfuscateBegin() {
base.deobfuscateBegin();
stringDecrypter.init(peImage, DeobfuscatedFile);
foreach (var info in stringDecrypter.DecrypterInfos) {
staticStringDecrypter.add(info.method, (method2, args) => {
return stringDecrypter.decrypt(method2, (int)args[0]);
});
}
DeobfuscatedFile.stringDecryptersAdded();
}
public override void deobfuscateMethodEnd(Blocks blocks) {
@ -111,6 +141,8 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
public override IEnumerable<string> getStringDecrypterMethods() {
var list = new List<string>();
foreach (var info in stringDecrypter.DecrypterInfos)
list.Add(info.method.MetadataToken.ToInt32().ToString("X8"));
return list;
}
}

20
de4dot.code/deobfuscators/dotNET_Reactor/EncryptedResource.cs
View File

@ -44,16 +44,20 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
public EncryptedResource(ModuleDefinition module, EncryptedResource oldOne) {
this.module = module;
resourceDecrypterMethod = module.LookupToken(oldOne.resourceDecrypterMethod.MetadataToken.ToInt32()) as MethodDefinition;
encryptedDataResource = DotNetUtils.getResource(module, oldOne.encryptedDataResource.Name) as EmbeddedResource;
if (oldOne.resourceDecrypterMethod != null)
resourceDecrypterMethod = module.LookupToken(oldOne.resourceDecrypterMethod.MetadataToken.ToInt32()) as MethodDefinition;
if (oldOne.encryptedDataResource != null)
encryptedDataResource = DotNetUtils.getResource(module, oldOne.encryptedDataResource.Name) as EmbeddedResource;
key = oldOne.key;
iv = oldOne.iv;
if (resourceDecrypterMethod == null || encryptedDataResource == null || key == null || iv == null)
if (resourceDecrypterMethod == null && oldOne.resourceDecrypterMethod != null)
throw new ApplicationException("Could not initialize EncryptedResource");
if (encryptedDataResource == null && oldOne.encryptedDataResource != null)
throw new ApplicationException("Could not initialize EncryptedResource");
}
public bool couldBeResourceDecrypter(MethodDefinition method) {
public bool couldBeResourceDecrypter(MethodDefinition method, IList<string> additionalTypes) {
if (!method.IsStatic)
return false;
if (method.Body == null)
@ -61,18 +65,16 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
if (method.Body.Instructions.Count < 1000)
return false;
var localTypes = new LocalTypes(method.Body.Variables);
var requiredTypes = new string[] {
var localTypes = new LocalTypes(method);
var requiredTypes = new List<string> {
"System.Byte[]",
"System.Diagnostics.StackFrame",
"System.IntPtr",
"System.IO.BinaryReader",
"System.IO.MemoryStream",
"System.Reflection.Assembly",
"System.Security.Cryptography.CryptoStream",
"System.Security.Cryptography.ICryptoTransform",
"System.Security.Cryptography.RijndaelManaged",
};
requiredTypes.AddRange(additionalTypes);
if (!localTypes.all(requiredTypes))
return false;

7
de4dot.code/deobfuscators/dotNET_Reactor/LocalTypes.cs
View File

@ -19,12 +19,17 @@
using System;
using System.Collections.Generic;
using Mono.Cecil;
using Mono.Cecil.Cil;
namespace de4dot.deobfuscators.dotNET_Reactor {
class LocalTypes {
Dictionary<string, int> localTypes = new Dictionary<string, int>(StringComparer.Ordinal);
public LocalTypes(MethodDefinition method)
: this(method.Body.Variables) {
}
public LocalTypes(IList<VariableDefinition> locals) {
foreach (var local in locals) {
var key = local.VariableType.FullName;
@ -38,7 +43,7 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
return localTypes.ContainsKey(typeFullName);
}
public bool all(string[] types) {
public bool all(IList<string> types) {
foreach (var typeName in types) {
if (!exists(typeName))
return false;

79
de4dot.code/deobfuscators/dotNET_Reactor/MethodsDecrypter.cs
View File

@ -46,6 +46,11 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
}
public void find() {
var additionalTypes = new string[] {
"System.Diagnostics.StackFrame",
"System.IntPtr",
"System.Reflection.Assembly",
};
var checkedMethods = new Dictionary<MethodReferenceAndDeclaringTypeKey, bool>();
var callCounter = new CallCounter();
int typesLeft = 30;
@ -63,7 +68,7 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
checkedMethods[key] = true;
if (!DotNetUtils.isMethod(method, "System.Void", "()"))
continue;
if (!encryptedResource.couldBeResourceDecrypter(method))
if (!encryptedResource.couldBeResourceDecrypter(method, additionalTypes))
continue;
}
callCounter.add(method);
@ -73,9 +78,9 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
encryptedResource.ResourceDecrypterMethod = (MethodDefinition)callCounter.most();
}
public byte[] decrypt(ISimpleDeobfuscator simpleDeobfuscator) {
public bool decrypt(PE.PeImage peImage, ISimpleDeobfuscator simpleDeobfuscator) {
if (encryptedResource.ResourceDecrypterMethod == null)
return null;
return false;
encryptedResource.init(simpleDeobfuscator);
initXorKey();
@ -94,46 +99,40 @@ namespace de4dot.deobfuscators.dotNET_Reactor {
}
}
using (var fileStream = new FileStream(module.FullyQualifiedName, FileMode.Open, FileAccess.Read, FileShare.Read)) {
byte[] fileData = new byte[(int)fileStream.Length];
fileStream.Read(fileData, 0, fileData.Length);
var peImage = new PE.PeImage(fileData);
var methodsDataReader = new BinaryReader(new MemoryStream(methodsData));
int patchCount = methodsDataReader.ReadInt32();
int mode = methodsDataReader.ReadInt32();
if (!useXorKey || mode == 1) {
for (int i = 0; i < patchCount; i++) {
uint rva = methodsDataReader.ReadUInt32();
uint data = methodsDataReader.ReadUInt32();
peImage.write(rva, BitConverter.GetBytes(data));
}
while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
uint rva = methodsDataReader.ReadUInt32();
uint token = methodsDataReader.ReadUInt32();
int size = methodsDataReader.ReadInt32();
if (size > 0)
peImage.write(rva, methodsDataReader.ReadBytes(size));
}
var methodsDataReader = new BinaryReader(new MemoryStream(methodsData));
int patchCount = methodsDataReader.ReadInt32();
int mode = methodsDataReader.ReadInt32();
if (!useXorKey || mode == 1) {
for (int i = 0; i < patchCount; i++) {
uint rva = methodsDataReader.ReadUInt32();
uint data = methodsDataReader.ReadUInt32();
peImage.write(rva, BitConverter.GetBytes(data));
}
else {
for (int i = 0; i < patchCount; i++) {
uint rva = methodsDataReader.ReadUInt32();
uint data = methodsDataReader.ReadUInt32();
peImage.write(rva, BitConverter.GetBytes(data));
}
int count = methodsDataReader.ReadInt32();
while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
uint rva = methodsDataReader.ReadUInt32();
uint token = methodsDataReader.ReadUInt32();
int size = methodsDataReader.ReadInt32();
if (size > 0)
peImage.write(rva, methodsDataReader.ReadBytes(size));
}
while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
uint rva = methodsDataReader.ReadUInt32();
uint token = methodsDataReader.ReadUInt32();
int size = methodsDataReader.ReadInt32();
if (size > 0)
peImage.write(rva, methodsDataReader.ReadBytes(size));
}
return fileData;
}
else {
for (int i = 0; i < patchCount; i++) {
uint rva = methodsDataReader.ReadUInt32();
uint data = methodsDataReader.ReadUInt32();
peImage.write(rva, BitConverter.GetBytes(data));
}
int count = methodsDataReader.ReadInt32();
while (methodsDataReader.BaseStream.Position < methodsData.Length - 1) {
uint rva = methodsDataReader.ReadUInt32();
uint token = methodsDataReader.ReadUInt32();
int size = methodsDataReader.ReadInt32();
if (size > 0)
peImage.write(rva, methodsDataReader.ReadBytes(size));
}
}
return true;
}
void initXorKey() {

186
de4dot.code/deobfuscators/dotNET_Reactor/StringDecrypter.cs Normal file
View File

@ -0,0 +1,186 @@
/*
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 System;
using System.Text;
using System.Collections.Generic;
using System.Security.Cryptography;
using Mono.Cecil;
using Mono.Cecil.Cil;
using de4dot.blocks;
namespace de4dot.deobfuscators.dotNET_Reactor {
class StringDecrypter {
ModuleDefinition module;
EncryptedResource encryptedResource;
List<DecrypterInfo> decrypterInfos = new List<DecrypterInfo>();
byte[] decryptedData;
PE.PeImage peImage;
public class DecrypterInfo {
public MethodDefinition method;
public byte[] key;
public byte[] iv;
public DecrypterInfo(MethodDefinition method, byte[] key, byte[] iv) {
this.method = method;
this.key = key;
this.iv = iv;
}
}
public bool Detected {
get { return encryptedResource.ResourceDecrypterMethod != null; }
}
public IEnumerable<DecrypterInfo> DecrypterInfos {
get { return decrypterInfos; }
}
public StringDecrypter(ModuleDefinition module) {
this.module = module;
this.encryptedResource = new EncryptedResource(module);
}
public StringDecrypter(ModuleDefinition module, StringDecrypter oldOne) {
this.module = module;
this.encryptedResource = new EncryptedResource(module, oldOne.encryptedResource);
foreach (var oldInfo in oldOne.decrypterInfos) {
var method = module.LookupToken(oldInfo.method.MetadataToken.ToInt32()) as MethodDefinition;
if (method == null)
throw new ApplicationException("Could not find string decrypter method");
decrypterInfos.Add(new DecrypterInfo(method, oldInfo.key, oldInfo.iv));
}
}
public void find() {
var additionalTypes = new string[] {
"System.String",
};
EmbeddedResource stringsResource = null;
foreach (var type in module.Types) {
if (type.BaseType == null || type.BaseType.FullName != "System.Object")
continue;
foreach (var method in type.Methods) {
if (!method.IsStatic || !method.HasBody)
continue;
if (!DotNetUtils.isMethod(method, "System.String", "(System.Int32)"))
continue;
if (!encryptedResource.couldBeResourceDecrypter(method, additionalTypes))
continue;
var resource = DotNetUtils.getResource(module, DotNetUtils.getCodeStrings(method)) as EmbeddedResource;
if (resource == null)
throw new ApplicationException("Could not find strings resource");
if (stringsResource != null && stringsResource != resource)
throw new ApplicationException("Two different string resources found");
stringsResource = resource;
encryptedResource.ResourceDecrypterMethod = method;
decrypterInfos.Add(new DecrypterInfo(method, null, null));
}
}
}
public void init(PE.PeImage peImage, ISimpleDeobfuscator simpleDeobfuscator) {
if (encryptedResource.ResourceDecrypterMethod == null)
return;
this.peImage = peImage;
foreach (var info in decrypterInfos)
findKeyIv(info.method, out info.key, out info.iv);
encryptedResource.init(simpleDeobfuscator);
decryptedData = encryptedResource.decrypt();
}
void findKeyIv(MethodDefinition method, out byte[] key, out byte[] iv) {
key = null;
iv = null;
var requiredTypes = new string[] {
"System.Byte[]",
"System.IO.MemoryStream",
"System.Security.Cryptography.CryptoStream",
"System.Security.Cryptography.Rijndael",
};
foreach (var info in DotNetUtils.getCalledMethods(module, method)) {
var calledMethod = info.Item2;
if (calledMethod.DeclaringType != method.DeclaringType)
continue;
var localTypes = new LocalTypes(calledMethod);
if (!localTypes.all(requiredTypes))
continue;
var instructions = calledMethod.Body.Instructions;
byte[] newKey = null, newIv = null;
for (int i = 0; i < instructions.Count && (newKey == null || newIv == null); i++) {
var instr = instructions[i];
if (instr.OpCode.Code != Code.Ldtoken)
continue;
var field = instr.Operand as FieldDefinition;
if (field == null)
continue;
if (field.InitialValue == null)
continue;
if (field.InitialValue.Length == 32)
newKey = field.InitialValue;
else if (field.InitialValue.Length == 16)
newIv = field.InitialValue;
}
if (newKey == null || newIv == null)
continue;
key = newKey;
iv = newIv;
return;
}
}
DecrypterInfo getDecrypterInfo(MethodDefinition method) {
foreach (var info in decrypterInfos) {
if (info.method == method)
return info;
}
throw new ApplicationException("Invalid string decrypter method");
}
public string decrypt(MethodDefinition method, int offset) {
var info = getDecrypterInfo(method);
if (info.key == null) {
int length = BitConverter.ToInt32(decryptedData, offset);
return Encoding.Unicode.GetString(decryptedData, offset + 4, length);
}
else {
uint rva = BitConverter.ToUInt32(decryptedData, offset);
int length = peImage.readInt32(rva);
var encryptedStringData = peImage.readBytes(rva + 4, length);
byte[] decryptedStringData;
using (var aes = new RijndaelManaged()) {
aes.Mode = CipherMode.CBC;
using (var transform = aes.CreateDecryptor(info.key, info.iv)) {
decryptedStringData = transform.TransformFinalBlock(encryptedStringData, 0, encryptedStringData.Length);
}
}
return Encoding.Unicode.GetString(decryptedStringData, 0, decryptedStringData.Length);
}
}
}
}