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Restore fields

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This commit is contained in:
de4dot 2012-01-24 17:10:11 +01:00
parent e00ca9a7d2
commit e9d7f3dbfb
3 changed files with 185 additions and 0 deletions
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1
de4dot.code/de4dot.code.csproj
View File

@ -87,6 +87,7 @@
<Compile Include="deobfuscators\CryptoObfuscator\ResourceResolver.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\StringDecrypter.cs" />
<Compile Include="deobfuscators\CryptoObfuscator\TamperDetection.cs" />
<Compile Include="deobfuscators\DeepSea\FieldsRestorer.cs" />
<Compile Include="deobfuscators\DeobfuscatorBase.cs" />
<Compile Include="deobfuscators\DeobfuscatorInfoBase.cs" />
<Compile Include="deobfuscators\DeobUtils.cs" />

20
de4dot.code/deobfuscators/DeepSea/Deobfuscator.cs
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@ -29,6 +29,7 @@ namespace de4dot.code.deobfuscators.DeepSea {
BoolOption removeInlinedMethods;
BoolOption decryptResources;
BoolOption dumpEmbeddedAssemblies;
BoolOption restoreFields;
public DeobfuscatorInfo()
: base() {
@ -36,6 +37,7 @@ namespace de4dot.code.deobfuscators.DeepSea {
removeInlinedMethods = new BoolOption(null, makeArgName("remove-inlined"), "Remove inlined methods", true);
decryptResources = new BoolOption(null, makeArgName("rsrc"), "Decrypt resources", true);
dumpEmbeddedAssemblies = new BoolOption(null, makeArgName("embedded"), "Dump embedded assemblies", true);
restoreFields = new BoolOption(null, makeArgName("fields"), "Restore fields", true);
}
public override string Name {
@ -53,6 +55,7 @@ namespace de4dot.code.deobfuscators.DeepSea {
RemoveInlinedMethods = removeInlinedMethods.get(),
DecryptResources = decryptResources.get(),
DumpEmbeddedAssemblies = dumpEmbeddedAssemblies.get(),
RestoreFields = restoreFields.get(),
});
}
@ -62,6 +65,7 @@ namespace de4dot.code.deobfuscators.DeepSea {
removeInlinedMethods,
decryptResources,
dumpEmbeddedAssemblies,
restoreFields,
};
}
}
@ -74,12 +78,14 @@ namespace de4dot.code.deobfuscators.DeepSea {
StringDecrypter stringDecrypter;
ResourceResolver resourceResolver;
AssemblyResolver assemblyResolver;
FieldsRestorer fieldsRestorer;
internal class Options : OptionsBase {
public bool InlineMethods { get; set; }
public bool RemoveInlinedMethods { get; set; }
public bool DecryptResources { get; set; }
public bool DumpEmbeddedAssemblies { get; set; }
public bool RestoreFields { get; set; }
}
public override string Type {
@ -170,6 +176,11 @@ done:
public override void deobfuscateBegin() {
base.deobfuscateBegin();
if (options.RestoreFields) {
fieldsRestorer = new FieldsRestorer(module);
fieldsRestorer.initialize();
}
foreach (var method in stringDecrypter.DecrypterMethods) {
staticStringInliner.add(method, (method2, args) => {
return stringDecrypter.decrypt(method2, args);
@ -213,9 +224,18 @@ done:
addMethodToBeRemoved(assemblyResolver.HandlerMethod, "Assembly resolver handler method");
}
public override void deobfuscateMethodEnd(blocks.Blocks blocks) {
if (options.RestoreFields)
fieldsRestorer.deobfuscate(blocks);
base.deobfuscateMethodEnd(blocks);
}
public override void deobfuscateEnd() {
removeInlinedMethods();
if (options.RestoreFields)
addTypesToBeRemoved(fieldsRestorer.FieldStructs, "Type with moved fields");
if (Operations.DecryptStrings != OpDecryptString.None) {
addMethodsToBeRemoved(stringDecrypter.DecrypterMethods, "String decrypter method");
stringDecrypter.cleanup();

164
de4dot.code/deobfuscators/DeepSea/FieldsRestorer.cs Normal file
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@ -0,0 +1,164 @@
/*
Copyright (C) 2011-2012 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.Collections.Generic;
using Mono.Cecil;
using Mono.Cecil.Cil;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.DeepSea {
// DS 4.x can move fields from a class to a struct. This class restores the fields.
class FieldsRestorer {
ModuleDefinition module;
TypeDefinitionDict<TypeDefinition> structToOwner = new TypeDefinitionDict<TypeDefinition>();
Dictionary<int, bool> oldFieldToken = new Dictionary<int, bool>();
public List<TypeDefinition> FieldStructs {
get {
var list = new List<TypeDefinition>(structToOwner.Count);
foreach (var structType in structToOwner.getKeys()) {
if (structType.Methods.Count != 0)
continue;
list.Add(structType);
}
return list;
}
}
public FieldsRestorer(ModuleDefinition module) {
this.module = module;
}
public void initialize() {
foreach (var kv in getMovedTypes()) {
var structType = kv.Key;
var ownerType = kv.Value;
structToOwner.add(structType, ownerType);
for (int i = 0; i < ownerType.Fields.Count; i++) {
if (DotNetUtils.getType(module, ownerType.Fields[i].FieldType) != structType)
continue;
oldFieldToken[ownerType.Fields[i].MetadataToken.ToInt32()] = true;
ownerType.Fields.RemoveAt(i);
break;
}
var structTypeFields = new List<FieldDefinition>(structType.Fields);
structType.Fields.Clear();
foreach (var field in structTypeFields)
ownerType.Fields.Add(field);
// Add a field so peverify won't complain if this type isn't removed
structType.Fields.Add(new FieldDefinition("a", FieldAttributes.Public, module.TypeSystem.Byte));
}
}
Dictionary<TypeDefinition, TypeDefinition> getMovedTypes() {
var fieldTypeToTypes = new Dictionary<TypeDefinition, List<TypeDefinition>>();
foreach (var type in module.GetTypes()) {
foreach (var field in type.Fields) {
var fieldType = DotNetUtils.getType(module, field.FieldType);
if (fieldType == null || !fieldType.IsValueType)
continue;
if ((fieldType.Attributes & ~TypeAttributes.Sealed) != TypeAttributes.NestedAssembly)
continue;
if (fieldType.NestedTypes.Count > 0)
continue;
if (fieldType.GenericParameters.Count > 0)
continue;
if (fieldType.Fields.Count == 0)
continue;
if (hasNonStaticMethods(fieldType))
continue;
List<TypeDefinition> list;
if (!fieldTypeToTypes.TryGetValue(fieldType, out list))
fieldTypeToTypes[fieldType] = list = new List<TypeDefinition>();
list.Add(type);
}
}
var candidates = new Dictionary<TypeDefinition, TypeDefinition>();
foreach (var kv in fieldTypeToTypes) {
if (kv.Value.Count != 1)
continue;
candidates[kv.Key] = kv.Value[0];
}
foreach (var type in module.GetTypes()) {
foreach (var field in type.Fields) {
if (field.DeclaringType != type)
removeType(candidates, field.FieldType);
}
foreach (var method in type.Methods) {
removeType(candidates, method.MethodReturnType.ReturnType);
foreach (var parameter in method.Parameters)
removeType(candidates, parameter.ParameterType);
if (method.Body != null) {
foreach (var local in method.Body.Variables)
removeType(candidates, local.VariableType);
}
}
}
return candidates;
}
void removeType(Dictionary<TypeDefinition, TypeDefinition> candidates, TypeReference type) {
var typeDef = DotNetUtils.getType(module, type);
if (typeDef == null)
return;
candidates.Remove(typeDef);
}
static bool hasNonStaticMethods(TypeDefinition type) {
foreach (var method in type.Methods) {
if (method.Name == ".cctor")
continue;
if (!method.IsStatic)
return true;
if (method.GenericParameters.Count > 0)
continue;
if (method.Body == null)
return true;
if (method.HasPInvokeInfo || method.PInvokeInfo != null)
return true;
}
return false;
}
public void deobfuscate(Blocks blocks) {
foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
var instrs = block.Instructions;
for (int i = instrs.Count - 1; i >= 0; i--) {
var instr = instrs[i];
if (instr.OpCode.Code != Code.Ldflda)
continue;
var field = instr.Operand as FieldReference;
if (field == null)
continue;
if (!oldFieldToken.ContainsKey(field.MetadataToken.ToInt32()))
continue;
instrs.RemoveAt(i);
}
}
}
}
}