/*
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 dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.DeepSea {
abstract class ResolverBase {
protected ModuleDefMD module;
protected ISimpleDeobfuscator simpleDeobfuscator;
protected IDeobfuscator deob;
protected MethodDef initMethod;
protected MethodDef resolveHandler;
protected FrameworkType frameworkType;
public MethodDef InitMethod {
get { return initMethod; }
}
public MethodDef HandlerMethod {
get { return resolveHandler; }
}
public bool Detected {
get { return initMethod != null; }
}
public ResolverBase(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator, IDeobfuscator deob) {
this.module = module;
this.frameworkType = DotNetUtils.GetFrameworkType(module);
this.simpleDeobfuscator = simpleDeobfuscator;
this.deob = deob;
}
public void Find() {
if (CheckCalledMethods(DotNetUtils.GetModuleTypeCctor(module)))
return;
if (CheckCalledMethods(module.EntryPoint))
return;
}
bool CheckCalledMethods(MethodDef checkMethod) {
if (checkMethod == null || checkMethod.Body == null)
return false;
foreach (var method in DotNetUtils.GetCalledMethods(module, checkMethod)) {
if (method.Name == ".cctor" || method.Name == ".ctor")
continue;
if (!method.IsStatic || !DotNetUtils.IsMethod(method, "System.Void", "()"))
continue;
if (CheckResolverInitMethod(method))
return true;
}
return false;
}
bool CheckResolverInitMethod(MethodDef resolverInitMethod) {
if (resolverInitMethod == null || resolverInitMethod.Body == null)
return false;
if (resolverInitMethod.Body.ExceptionHandlers.Count != 1)
return false;
switch (frameworkType) {
case FrameworkType.Silverlight:
return CheckResolverInitMethodSilverlight(resolverInitMethod);
default:
return CheckResolverInitMethodDesktop(resolverInitMethod);
}
}
bool CheckResolverInitMethodDesktop(MethodDef resolverInitMethod) {
simpleDeobfuscator.Deobfuscate(resolverInitMethod);
if (!CheckResolverInitMethodInternal(resolverInitMethod))
return false;
foreach (var resolveHandlerMethod in GetLdftnMethods(resolverInitMethod)) {
if (!CheckHandlerMethodDesktop(resolveHandlerMethod))
continue;
initMethod = resolverInitMethod;
resolveHandler = resolveHandlerMethod;
return true;
}
return false;
}
protected virtual bool CheckResolverInitMethodSilverlight(MethodDef resolverInitMethod) {
return false;
}
protected abstract bool CheckResolverInitMethodInternal(MethodDef resolverInitMethod);
IEnumerable GetLdftnMethods(MethodDef method) {
var list = new List();
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code != Code.Ldftn)
continue;
var loadedMethod = instr.Operand as MethodDef;
if (loadedMethod != null)
list.Add(loadedMethod);
}
return list;
}
bool CheckHandlerMethodDesktop(MethodDef handler) {
if (handler == null || handler.Body == null || !handler.IsStatic)
return false;
if (!DotNetUtils.IsMethod(handler, "System.Reflection.Assembly", "(System.Object,System.ResolveEventArgs)"))
return false;
return CheckHandlerMethodDesktopInternal(handler);
}
protected abstract bool CheckHandlerMethodDesktopInternal(MethodDef handler);
// 3.0.3.41 - 3.0.4.44
protected static byte[] DecryptResourceV3Old(EmbeddedResource resource) {
return DecryptResourceV3Old(resource.GetResourceData());
}
// 3.0.3.41 - 3.0.4.44
protected static byte[] DecryptResourceV3Old(byte[] data) {
return DecryptResource(data, 0, data.Length, 0);
}
protected static byte[] DecryptResourceV41SL(EmbeddedResource resource) {
var data = resource.GetResourceData();
byte k = data[0];
for (int i = 0; i < data.Length - 1; i++)
data[i + 1] ^= (byte)((k << (i & 5)) + i);
return InflateIfNeeded(data, 1, data.Length - 1);
}
protected static byte[] DecryptResourceV3(EmbeddedResource resource) {
return DecryptResourceV3(resource.GetResourceData());
}
protected static byte[] DecryptResourceV3(byte[] data) {
return DecryptResource(data, 1, data.Length - 1, data[0]);
}
protected static byte[] DecryptResourceV4(byte[] data, int magic) {
return DecryptResource(data, 0, data.Length, magic);
}
protected static byte[] DecryptResource(byte[] data, int start, int len, int magic) {
for (int i = start; i < start + len; i++)
data[i] ^= (byte)(i - start + magic);
return InflateIfNeeded(data, start, len);
}
protected static byte[] InflateIfNeeded(byte[] data) {
return InflateIfNeeded(data, 0, data.Length);
}
protected static byte[] InflateIfNeeded(byte[] data, int start, int len) {
if (BitConverter.ToInt16(data, start) != 0x5A4D)
return DeobUtils.Inflate(data, start, len, true);
var data2 = new byte[len];
Array.Copy(data, start, data2, 0, data2.Length);
return data2;
}
}
}