/*
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 .
*/
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Goliath_NET {
class StrongNameChecker {
ModuleDefMD module;
TypeDef strongNameType;
MethodDef strongNameCheckMethod;
public bool Detected {
get { return strongNameType != null;}
}
public TypeDef Type {
get { return strongNameType; }
}
public MethodDef CheckerMethod {
get { return strongNameCheckMethod; }
}
public StrongNameChecker(ModuleDefMD module) {
this.module = module;
}
public void find() {
foreach (var type in module.Types) {
if (type.HasFields || type.HasEvents || type.HasProperties)
continue;
var checkMethod = getAntiTamperingDetectionMethod(type);
if (checkMethod == null)
continue;
if (DotNetUtils.getMethod(type, "System.Byte[]", "(System.Reflection.Assembly)") == null)
continue;
if (DotNetUtils.getMethod(type, "System.String", "(System.Collections.Generic.Stack`1)") == null)
continue;
if (DotNetUtils.getMethod(type, "System.Int32", "(System.Int32,System.Byte[])") == null)
continue;
strongNameType = type;
strongNameCheckMethod = checkMethod;
return;
}
}
MethodDef getAntiTamperingDetectionMethod(TypeDef type) {
var requiredLocals = new string[] {
"System.Reflection.Assembly",
"System.Collections.Generic.Stack`1",
};
foreach (var method in type.Methods) {
if (!method.IsStatic || method.Body == null)
continue;
if (!DotNetUtils.isMethod(method, "System.Void", "(System.Type)"))
continue;
if (!new LocalTypes(method).all(requiredLocals))
continue;
if (!hasThrow(method))
continue;
return method;
}
return null;
}
static bool hasThrow(MethodDef method) {
if (method == null || method.Body == null)
return false;
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code == Code.Throw)
return true;
}
return false;
}
public bool deobfuscate(Blocks blocks) {
if (blocks.Method.Name != ".cctor" && blocks.Method.Name != ".ctor")
return false;
foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
var instrs = block.Instructions;
for (int i = 0; i < instrs.Count - 2; i++) {
var ldtoken = instrs[i];
if (ldtoken.OpCode.Code != Code.Ldtoken)
continue;
var call1 = instrs[i + 1];
if (call1.OpCode.Code != Code.Call && call1.OpCode.Code != Code.Callvirt)
continue;
if (!DotNetUtils.isMethod(call1.Operand as IMethod, "System.Type", "(System.RuntimeTypeHandle)"))
continue;
var call2 = instrs[i + 2];
if (call2.OpCode.Code != Code.Call && call2.OpCode.Code != Code.Callvirt)
continue;
if (!MethodEqualityComparer.CompareDeclaringTypes.Equals(call2.Operand as IMethod, strongNameCheckMethod))
continue;
block.remove(i, 3);
return true;
}
}
return false;
}
}
}