/*
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 System.Collections.Generic;
using dot10.DotNet;
using dot10.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Eazfuscator_NET {
interface IDynocodeGenerator {
IEnumerable getValues(int input);
}
// Something added in EF 3.5 which they call Dynocode. The string decrypter can now
// call some iterator classes that will return some integers that it will use to
// XOR some key.
class Dynocode {
ISimpleDeobfuscator simpleDeobfuscator;
Dictionary typeToDCGen = new Dictionary();
class DCGen1 : IDynocodeGenerator {
public int magic1;
public int magic2;
public int magic3;
public int magic4;
public int magic5;
public int magic6;
public int magic7;
public IEnumerable getValues(int input) {
yield return magic1;
yield return magic2;
yield return input ^ magic3;
yield return magic4;
yield return magic5;
yield return magic6;
yield return input ^ magic7;
}
}
class DCGen2 : IDynocodeGenerator {
public int magic1;
public IEnumerable getValues(int input) {
int x = 0;
int y = 1;
while (true) {
yield return y;
if (--input == 0)
break;
int tmp = y;
y = (x + y + input) ^ magic1;
x = tmp;
}
}
}
class DCGen3 : IDynocodeGenerator {
public int magic1;
public int magic2;
public DCGen2 dc2;
public IEnumerable getValues(int input) {
int i = 7;
foreach (var val in dc2.getValues(input)) {
int x = val ^ input;
if ((x % 4) == 0)
x ^= magic1;
if ((x % 16) == 0)
x ^= magic2;
yield return x;
if (--i == 0)
break;
}
}
}
public IEnumerable Types {
get { return typeToDCGen.Keys; }
}
public Dynocode(ISimpleDeobfuscator simpleDeobfuscator) {
this.simpleDeobfuscator = simpleDeobfuscator;
}
public IDynocodeGenerator getDynocodeGenerator(TypeDef type) {
if (type == null)
return null;
var dt = type.DeclaringType;
if (dt == null)
return null;
IDynocodeGenerator dcGen;
if (typeToDCGen.TryGetValue(type, out dcGen))
return dcGen;
if (dt.NestedTypes.Count == 1)
dcGen = getDCGen1(type);
else if (dt.NestedTypes.Count == 2)
dcGen = getDCGen3(type);
typeToDCGen[type] = dcGen;
return dcGen;
}
DCGen1 getDCGen1(TypeDef type) {
var method = getMoveNext(type);
if (method == null)
return null;
simpleDeobfuscator.deobfuscate(method);
var swLabels = getSwitchLabels(method);
if (swLabels == null || swLabels.Count < 7)
return null;
var dcGen = new DCGen1();
if (!getMagicDC1(method, swLabels[0], out dcGen.magic1))
return null;
if (!getMagicDC1(method, swLabels[1], out dcGen.magic2))
return null;
if (!getMagicXorDC1(method, swLabels[2], out dcGen.magic3))
return null;
if (!getMagicDC1(method, swLabels[3], out dcGen.magic4))
return null;
if (!getMagicDC1(method, swLabels[4], out dcGen.magic5))
return null;
if (!getMagicDC1(method, swLabels[5], out dcGen.magic6))
return null;
if (!getMagicXorDC1(method, swLabels[6], out dcGen.magic7))
return null;
return dcGen;
}
static IList getSwitchLabels(MethodDef method) {
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code != Code.Switch)
continue;
return instr.Operand as IList;
}
return null;
}
static bool getMagicDC1(MethodDef method, Instruction target, out int magic) {
magic = 0;
var instrs = method.Body.Instructions;
int index = instrs.IndexOf(target);
if (index < 0)
return false;
for (int i = index; i < instrs.Count - 3; i++) {
var instr = instrs[i];
if (instr.OpCode.FlowControl != FlowControl.Next)
return false;
if (instr.OpCode.Code != Code.Stfld)
continue;
if (instrs[i + 1].OpCode.Code != Code.Ldarg_0)
continue;
var ldci4 = instrs[i + 2];
if (!ldci4.IsLdcI4())
continue;
if (instrs[i + 3].OpCode.Code != Code.Stfld)
continue;
magic = ldci4.GetLdcI4Value();
return true;
}
return false;
}
static bool getMagicXorDC1(MethodDef method, Instruction target, out int magic) {
magic = 0;
var instrs = method.Body.Instructions;
int index = instrs.IndexOf(target);
if (index < 0)
return false;
for (int i = index; i < instrs.Count - 2; i++) {
var instr = instrs[i];
if (instr.OpCode.FlowControl != FlowControl.Next)
return false;
if (!instr.IsLdcI4())
continue;
if (instrs[i + 1].OpCode.Code != Code.Xor)
continue;
if (instrs[i + 2].OpCode.Code != Code.Stfld)
continue;
magic = instr.GetLdcI4Value();
return true;
}
return false;
}
DCGen3 getDCGen3(TypeDef type) {
var method = getMoveNext(type);
if (method == null)
return null;
simpleDeobfuscator.deobfuscate(method);
var dcGen = new DCGen3();
int index = 0;
if (!getMagicDC3(method, ref index, out dcGen.magic1))
return null;
if (!getMagicDC3(method, ref index, out dcGen.magic2))
return null;
var dt = type.DeclaringType;
dcGen.dc2 = getDCGen2(dt.NestedTypes[0] == type ? dt.NestedTypes[1] : dt.NestedTypes[0]);
return dcGen;
}
static bool getMagicDC3(MethodDef method, ref int index, out int magic) {
var instrs = method.Body.Instructions;
for (int i = index; i < instrs.Count - 2; i++) {
var ldci4 = instrs[i];
if (!ldci4.IsLdcI4())
continue;
if (instrs[i + 1].OpCode.Code != Code.Xor)
continue;
if (instrs[i + 2].OpCode.Code != Code.Stfld)
continue;
index = i + 3;
magic = ldci4.GetLdcI4Value();
return true;
}
magic = 0;
return false;
}
DCGen2 getDCGen2(TypeDef type) {
var method = getMoveNext(type);
if (method == null)
return null;
simpleDeobfuscator.deobfuscate(method);
var dcGen = new DCGen2();
int index = 0;
if (!getMagicDC3(method, ref index, out dcGen.magic1))
return null;
return dcGen;
}
static MethodDef getMoveNext(TypeDef type) {
foreach (var m in type.Methods) {
if (!m.IsVirtual)
continue;
foreach (var mo in m.Overrides) {
if (mo.MethodDeclaration.FullName == "System.Boolean System.Collections.IEnumerator::MoveNext()")
return m;
}
}
foreach (var m in type.Methods) {
if (!m.IsVirtual)
continue;
if (m.Name != "MoveNext")
continue;
if (!DotNetUtils.isMethod(m, "System.Boolean", "()"))
continue;
return m;
}
return null;
}
}
}