/*
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 .
*/
using System.Collections.Generic;
using Mono.Cecil;
using Mono.Cecil.Cil;
using de4dot.blocks;
namespace de4dot.deobfuscators {
// Restore the type of all fields / parameters that have had their type turned into object.
// This thing requires a lot more code than I have time to do now (similar to symbol renaming)
// so it will be a basic implementation only.
class TypesRestorer {
ModuleDefinition module;
List allMethods;
Dictionary> argInfos = new Dictionary>();
List> changedArgInfos = new List>();
List> changedReturnTypes = new List>();
TypeInfo methodReturnInfo;
Dictionary> fieldWrites = new Dictionary>();
class TypeInfo {
public Dictionary types = new Dictionary();
public TypeReference newType = null;
public T arg;
public TypeInfo(T arg) {
this.arg = arg;
}
public bool updateNewType() {
if (types.Count == 0)
return false;
TypeReference theNewType = null;
foreach (var key in types.Keys) {
if (theNewType == null) {
theNewType = key.TypeReference;
continue;
}
theNewType = getCommonBaseClass(theNewType, key.TypeReference);
if (theNewType == null)
break;
}
if (theNewType == null)
return false;
if (MemberReferenceHelper.compareTypes(theNewType, newType))
return false;
newType = theNewType;
return true;
}
}
public TypesRestorer(ModuleDefinition module) {
this.module = module;
}
public void deobfuscate() {
allMethods = new List();
foreach (var type in module.GetTypes())
allMethods.AddRange(type.Methods);
foreach (var type in module.GetTypes()) {
foreach (var field in type.Fields) {
if (!MemberReferenceHelper.isSystemObject(field.FieldType))
continue;
var key = new FieldReferenceAndDeclaringTypeKey(field);
fieldWrites[key] = new TypeInfo(field);
}
}
for (int i = 0; i < 10; i++) {
bool changed = false;
changed |= deobfuscateFields();
changed |= deobfuscateMethods();
if (!changed)
break;
}
}
bool deobfuscateMethods() {
changedArgInfos.Clear();
changedReturnTypes.Clear();
foreach (var method in allMethods) {
methodReturnInfo = new TypeInfo(method.MethodReturnType.Parameter2);
deobfuscateMethod(method);
if (methodReturnInfo.updateNewType())
changedReturnTypes.Add(methodReturnInfo);
foreach (var info in argInfos.Values) {
if (info.updateNewType())
changedArgInfos.Add(info);
}
}
if (changedArgInfos.Count == 0 && changedReturnTypes.Count == 0)
return false;
changedArgInfos.Sort((a, b) => sortTypeInfos(a, b));
changedReturnTypes.Sort((a, b) => sortTypeInfos(a, b));
bool changed = false;
if (changedArgInfos.Count > 0) {
Log.v("Changing method arg types from object -> real type");
Log.indent();
IMethodSignature updatedMethod = null;
Log.indent();
foreach (var info in changedArgInfos) {
if (info.newType == null || MemberReferenceHelper.isSystemObject(info.newType))
continue;
if (updatedMethod == null || updatedMethod != info.arg.Method) {
updatedMethod = info.arg.Method;
Log.deIndent();
Log.v("Method {0:X8}", updatedMethod.MetadataToken.ToInt32());
Log.indent();
}
Log.v("{0}: new type: {1} ({2:X8})", info.arg.Index, info.newType, info.newType.MetadataToken.ToInt32());
info.arg.ParameterType = info.newType;
changed = true;
}
Log.deIndent();
Log.deIndent();
}
if (changedReturnTypes.Count > 0) {
Log.v("Changing method return types from object -> real type");
Log.indent();
foreach (var info in changedReturnTypes) {
if (info.newType == null || MemberReferenceHelper.isSystemObject(info.newType))
continue;
Log.v("{0:X8}: new type {1} ({2:X8})", info.arg.Method.MetadataToken.ToInt32(), info.newType, info.newType.MetadataToken.ToInt32());
info.arg.Method.MethodReturnType.ReturnType = info.newType;
info.arg.ParameterType = info.newType;
changed = true;
}
Log.deIndent();
}
return changed;
}
static int sortTypeInfos(TypeInfo a, TypeInfo b) {
if (a.arg.Method.MetadataToken.ToInt32() < b.arg.Method.MetadataToken.ToInt32())
return -1;
if (a.arg.Method.MetadataToken.ToInt32() > b.arg.Method.MetadataToken.ToInt32())
return 1;
if (a.arg.Index < b.arg.Index)
return -1;
if (a.arg.Index < b.arg.Index)
return 1;
return 0;
}
void deobfuscateMethod(MethodDefinition method) {
if (!method.IsStatic || method.Body == null)
return;
bool fixReturnType = MemberReferenceHelper.isSystemObject(method.MethodReturnType.ReturnType);
argInfos.Clear();
foreach (var arg in method.Parameters) {
if (arg.ParameterType == null || arg.ParameterType.IsValueType)
continue;
if (!MemberReferenceHelper.isSystemObject(arg.ParameterType))
continue;
argInfos[arg] = new TypeInfo(arg);
}
if (argInfos.Count == 0 && !fixReturnType)
return;
var methodParams = DotNetUtils.getParameters(method);
var reversedMethodParams = new List(methodParams);
reversedMethodParams.Reverse();
List args;
var instructions = method.Body.Instructions;
for (int i = 0; i < instructions.Count; i++) {
var instr = instructions[i];
switch (instr.OpCode.Code) {
case Code.Ret:
if (!fixReturnType)
break;
var type = getLoadedType(method, instructions, i);
if (type == null)
break;
methodReturnInfo.types[new TypeReferenceKey(type)] = true;
break;
case Code.Call:
case Code.Calli:
case Code.Callvirt:
args = getPushedArgInstructions(instructions, i);
var calledMethod = instr.Operand as MethodReference;
if (calledMethod == null)
break;
var calledMethodParams = DotNetUtils.getParameters(calledMethod);
for (int j = 0; j < args.Count; j++) {
int calledMethodParamIndex = calledMethodParams.Count - j - 1;
var ldInstr = args[j];
switch (ldInstr.OpCode.Code) {
case Code.Ldarg:
case Code.Ldarg_S:
case Code.Ldarg_0:
case Code.Ldarg_1:
case Code.Ldarg_2:
case Code.Ldarg_3:
addMethodArgType(getParameter(methodParams, method, ldInstr), DotNetUtils.getParameter(calledMethodParams, calledMethodParamIndex));
break;
default:
break;
}
}
break;
case Code.Castclass:
args = getPushedArgInstructions(instructions, i);
if (args.Count < 1)
break;
addMethodArgType(getParameter(methodParams, method, args[0]), instr.Operand as TypeReference);
break;
case Code.Stloc:
case Code.Stloc_S:
case Code.Stloc_0:
case Code.Stloc_1:
case Code.Stloc_2:
case Code.Stloc_3:
args = getPushedArgInstructions(instructions, i);
if (args.Count < 1)
break;
addMethodArgType(getParameter(methodParams, method, args[0]), DotNetUtils.getLocalVar(method.Body.Variables, instr));
break;
case Code.Stsfld:
args = getPushedArgInstructions(instructions, i);
if (args.Count < 1)
break;
addMethodArgType(getParameter(methodParams, method, args[0]), instr.Operand as FieldReference);
break;
case Code.Stfld:
args = getPushedArgInstructions(instructions, i);
if (args.Count >= 1) {
var field = instr.Operand as FieldReference;
addMethodArgType(getParameter(methodParams, method, args[0]), field);
if (args.Count >= 2 && field != null)
addMethodArgType(getParameter(methodParams, method, args[1]), field.DeclaringType);
}
break;
case Code.Ldfld:
case Code.Ldflda:
args = getPushedArgInstructions(instructions, i);
if (args.Count < 1)
break;
addMethodArgType(getParameter(methodParams, method, args[0]), instr.Operand as FieldReference);
break;
//TODO: For better results, these should be checked:
case Code.Starg:
case Code.Starg_S:
case Code.Ldelema:
case Code.Ldelem_Any:
case Code.Ldelem_I:
case Code.Ldelem_I1:
case Code.Ldelem_I2:
case Code.Ldelem_I4:
case Code.Ldelem_I8:
case Code.Ldelem_R4:
case Code.Ldelem_R8:
case Code.Ldelem_Ref:
case Code.Ldelem_U1:
case Code.Ldelem_U2:
case Code.Ldelem_U4:
case Code.Ldind_I:
case Code.Ldind_I1:
case Code.Ldind_I2:
case Code.Ldind_I4:
case Code.Ldind_I8:
case Code.Ldind_R4:
case Code.Ldind_R8:
case Code.Ldind_Ref:
case Code.Ldind_U1:
case Code.Ldind_U2:
case Code.Ldind_U4:
case Code.Ldobj:
case Code.Stelem_Any:
case Code.Stelem_I:
case Code.Stelem_I1:
case Code.Stelem_I2:
case Code.Stelem_I4:
case Code.Stelem_I8:
case Code.Stelem_R4:
case Code.Stelem_R8:
case Code.Stelem_Ref:
case Code.Stind_I:
case Code.Stind_I1:
case Code.Stind_I2:
case Code.Stind_I4:
case Code.Stind_I8:
case Code.Stind_R4:
case Code.Stind_R8:
case Code.Stind_Ref:
case Code.Stobj:
default:
break;
}
}
}
static ParameterDefinition getParameter(IList parameters, MethodReference method, Instruction instr) {
switch (instr.OpCode.Code) {
case Code.Ldarg:
case Code.Ldarg_S:
case Code.Ldarg_0:
case Code.Ldarg_1:
case Code.Ldarg_2:
case Code.Ldarg_3:
return DotNetUtils.getParameter(parameters, method, instr);
default:
return null;
}
}
bool addMethodArgType(ParameterDefinition methodParam, FieldReference field) {
if (field == null)
return false;
return addMethodArgType(methodParam, field.FieldType);
}
bool addMethodArgType(ParameterDefinition methodParam, VariableDefinition otherLocal) {
if (otherLocal == null)
return false;
return addMethodArgType(methodParam, otherLocal.VariableType);
}
bool addMethodArgType(ParameterDefinition methodParam, ParameterDefinition otherParam) {
if (otherParam == null)
return false;
return addMethodArgType(methodParam, otherParam.ParameterType);
}
bool addMethodArgType(ParameterDefinition methodParam, TypeReference type) {
if (methodParam == null || type == null)
return false;
if (!isValidType(type))
return false;
TypeInfo info;
if (!argInfos.TryGetValue(methodParam, out info))
return false;
var key = new TypeReferenceKey(type);
if (info.types.ContainsKey(key))
return false;
info.types[key] = true;
return true;
}
// May not return all args. The args are returned in reverse order.
List getPushedArgInstructions(IList instructions, int index) {
int pushes, pops;
DotNetUtils.calculateStackUsage(instructions[index], false, out pushes, out pops);
if (pops == -1)
return new List();
return getPushedArgInstructions(instructions, index, pops);
}
// May not return all args. The args are returned in reverse order.
List getPushedArgInstructions(IList instructions, int index, int numArgs) {
List args = new List(numArgs);
int skipPushes = 0;
while (index >= 0 && args.Count < numArgs) {
var instr = getPreviousInstruction(instructions, ref index);
if (instr == null)
break;
int pushes, pops;
DotNetUtils.calculateStackUsage(instr, false, out pushes, out pops);
if (pops == -1)
break;
if (pushes > 1)
break; // dup
if (skipPushes > 0) {
skipPushes -= pushes;
if (skipPushes < 0)
break;
skipPushes += pops;
}
else {
if (pushes == 1)
args.Add(instr);
skipPushes += pops;
}
}
return args;
}
bool deobfuscateFields() {
if (!updateFields())
return false;
var infos = new List>(fieldWrites.Values);
infos.Sort((a, b) => {
if (a.arg.DeclaringType.MetadataToken.ToInt32() < b.arg.DeclaringType.MetadataToken.ToInt32()) return -1;
if (a.arg.DeclaringType.MetadataToken.ToInt32() > b.arg.DeclaringType.MetadataToken.ToInt32()) return 1;
if (a.arg.MetadataToken.ToInt32() < b.arg.MetadataToken.ToInt32()) return -1;
if (a.arg.MetadataToken.ToInt32() > b.arg.MetadataToken.ToInt32()) return 1;
return 0;
});
if (infos.Count == 0)
return false;
Log.v("Changing field types from object -> real type");
Log.indent();
bool changed = false;
foreach (var info in infos) {
if (info.newType == null || MemberReferenceHelper.isSystemObject(info.newType))
continue;
fieldWrites.Remove(new FieldReferenceAndDeclaringTypeKey(info.arg));
Log.v("{0:X8}: new type: {1} ({2:X8})", info.arg.MetadataToken.ToInt32(), info.newType, info.newType.MetadataToken.ToInt32());
info.arg.FieldType = info.newType;
changed = true;
}
Log.deIndent();
return changed;
}
bool updateFields() {
foreach (var info in fieldWrites.Values)
info.types.Clear();
foreach (var method in allMethods) {
if (method.Body == null)
continue;
var instructions = method.Body.Instructions;
for (int i = 0; i < instructions.Count; i++) {
var instr = instructions[i];
if (instr.OpCode.Code != Code.Stfld && instr.OpCode.Code != Code.Stsfld)
continue;
var field = instr.Operand as FieldReference;
TypeInfo info;
if (!fieldWrites.TryGetValue(new FieldReferenceAndDeclaringTypeKey(field), out info))
continue;
var fieldType = getLoadedType(method, instructions, i);
if (fieldType == null)
continue;
info.types[new TypeReferenceKey(fieldType)] = true;
}
}
bool changed = false;
foreach (var info in fieldWrites.Values)
changed |= info.updateNewType();
return changed;
}
TypeReference getLoadedType(MethodDefinition method, IList instructions, int instrIndex) {
var prev = getPreviousInstruction(instructions, ref instrIndex);
if (prev == null)
return null;
TypeReference fieldType;
switch (prev.OpCode.Code) {
case Code.Ldstr:
fieldType = module.TypeSystem.String;
break;
case Code.Call:
case Code.Calli:
case Code.Callvirt:
var calledMethod = prev.Operand as MethodReference;
if (calledMethod == null)
return null;
fieldType = calledMethod.MethodReturnType.ReturnType;
break;
case Code.Newarr:
fieldType = prev.Operand as TypeReference;
if (fieldType == null)
return null;
fieldType = new ArrayType(fieldType);
break;
case Code.Newobj:
var ctor = prev.Operand as MethodReference;
if (ctor == null)
return null;
fieldType = ctor.DeclaringType;
break;
case Code.Castclass:
case Code.Isinst:
fieldType = prev.Operand as TypeReference;
break;
case Code.Ldarg:
case Code.Ldarg_S:
case Code.Ldarg_0:
case Code.Ldarg_1:
case Code.Ldarg_2:
case Code.Ldarg_3:
fieldType = DotNetUtils.getArgType(method, prev);
break;
case Code.Ldloc:
case Code.Ldloc_S:
case Code.Ldloc_0:
case Code.Ldloc_1:
case Code.Ldloc_2:
case Code.Ldloc_3:
var local = DotNetUtils.getLocalVar(method.Body.Variables, prev);
if (local == null)
return null;
fieldType = local.VariableType;
break;
case Code.Ldfld:
case Code.Ldsfld:
var field2 = prev.Operand as FieldReference;
if (field2 == null)
return null;
fieldType = field2.FieldType;
break;
default:
return null;
}
if (!isValidType(fieldType))
return null;
return fieldType;
}
static bool isValidType(TypeReference type) {
if (type == null)
return false;
if (type.IsValueType)
return false;
if (MemberReferenceHelper.isSystemObject(type))
return false;
if (MemberReferenceHelper.verifyType(type, "mscorlib", "System.Void"))
return false;
if (type is GenericParameter)
return false;
return true;
}
static TypeReference getCommonBaseClass(TypeReference a, TypeReference b) {
return null; //TODO:
}
static Instruction getPreviousInstruction(IList instructions, ref int instrIndex) {
while (true) {
instrIndex--;
if (instrIndex < 0)
return null;
var instr = instructions[instrIndex];
if (instr.OpCode.Code == Code.Nop)
continue;
if (instr.OpCode.OpCodeType == OpCodeType.Prefix)
continue;
switch (instr.OpCode.FlowControl) {
case FlowControl.Next:
case FlowControl.Call:
return instr;
default:
return null;
}
}
}
}
}