/*
Copyright (C) 2011-2013 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 System.IO;
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Confuser {
class ResourceDecrypter : IVersionProvider {
ModuleDefMD module;
ISimpleDeobfuscator simpleDeobfuscator;
MethodDef handler;
MethodDef installMethod;
EmbeddedResource resource;
Dictionary fields = new Dictionary();
byte key0, key1;
ConfuserVersion version = ConfuserVersion.Unknown;
enum ConfuserVersion {
Unknown,
v14_r55802,
v17_r73404,
v17_r73822,
v18_r75367,
v18_r75369,
}
public IEnumerable Fields {
get { return fields.Keys; }
}
public MethodDef Handler {
get { return handler; }
}
public bool Detected {
get { return handler != null; }
}
public ResourceDecrypter(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator) {
this.module = module;
this.simpleDeobfuscator = simpleDeobfuscator;
}
public void Find() {
if (CheckMethod(DotNetUtils.GetModuleTypeCctor(module)))
return;
}
bool CheckMethod(MethodDef method) {
if (method == null || method.Body == null)
return false;
if (!DotNetUtils.CallsMethod(method, "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)"))
return false;
simpleDeobfuscator.Deobfuscate(method, true);
fields.Clear();
var tmpHandler = GetHandler(method);
if (tmpHandler == null || tmpHandler.DeclaringType != method.DeclaringType)
return false;
var tmpResource = FindResource(tmpHandler);
if (tmpResource == null)
return false;
simpleDeobfuscator.Deobfuscate(tmpHandler, true);
ConfuserVersion tmpVersion = ConfuserVersion.Unknown;
if (DotNetUtils.CallsMethod(tmpHandler, "System.Object System.AppDomain::GetData(System.String)")) {
if (!DotNetUtils.CallsMethod(tmpHandler, "System.Void System.Buffer::BlockCopy(System.Array,System.Int32,System.Array,System.Int32,System.Int32)")) {
if (!FindKey0Key1_v14_r55802(tmpHandler, out key0, out key1))
return false;
tmpVersion = ConfuserVersion.v14_r55802;
}
else if (FindKey0_v17_r73404(tmpHandler, out key0) && FindKey1_v17_r73404(tmpHandler, out key1))
tmpVersion = ConfuserVersion.v17_r73404;
else
return false;
}
else {
if (AddFields(FindFields(tmpHandler, method.DeclaringType)) != 1)
return false;
if (FindKey0_v17_r73404(tmpHandler, out key0) && FindKey1_v17_r73404(tmpHandler, out key1))
tmpVersion = ConfuserVersion.v17_r73822;
else if (FindKey0_v18_r75367(tmpHandler, out key0) && FindKey1_v17_r73404(tmpHandler, out key1))
tmpVersion = ConfuserVersion.v18_r75367;
else if (FindKey0_v18_r75369(tmpHandler, out key0) && FindKey1_v18_r75369(tmpHandler, out key1))
tmpVersion = ConfuserVersion.v18_r75369;
else
return false;
}
handler = tmpHandler;
resource = tmpResource;
installMethod = method;
version = tmpVersion;
return true;
}
static MethodDef GetHandler(MethodDef method) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count - 2; i++) {
var ldftn = instrs[i];
if (ldftn.OpCode.Code != Code.Ldftn)
continue;
var handler = ldftn.Operand as MethodDef;
if (handler == null)
continue;
var newobj = instrs[i + 1];
if (newobj.OpCode.Code != Code.Newobj)
continue;
var callvirt = instrs[i + 2];
if (callvirt.OpCode.Code != Code.Callvirt)
continue;
var calledMethod = callvirt.Operand as IMethod;
if (calledMethod == null)
continue;
if (calledMethod.FullName != "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)")
continue;
return handler;
}
return null;
}
int AddFields(IEnumerable moreFields) {
int count = 0;
foreach (var field in moreFields) {
if (AddField(field))
count++;
}
return count;
}
bool AddField(FieldDef field) {
if (field == null)
return false;
if (fields.ContainsKey(field))
return false;
fields[field] = true;
return true;
}
static IEnumerable FindFields(MethodDef method, TypeDef declaringType) {
var fields = new List();
foreach (var instr in method.Body.Instructions) {
var field = instr.Operand as FieldDef;
if (field != null && field.DeclaringType == declaringType)
fields.Add(field);
}
return fields;
}
EmbeddedResource FindResource(MethodDef method) {
return DotNetUtils.GetResource(module, DotNetUtils.GetCodeStrings(method)) as EmbeddedResource;
}
static bool FindKey0_v18_r75367(MethodDef method, out byte key0) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count; i++) {
i = ConfuserUtils.FindCallMethod(instrs, i, Code.Callvirt, "System.Int32 System.IO.Stream::Read(System.Byte[],System.Int32,System.Int32)");
if (i < 0)
break;
if (i + 3 >= instrs.Count)
break;
if (instrs[i + 1].OpCode.Code != Code.Pop)
continue;
var ldci4 = instrs[i + 2];
if (!ldci4.IsLdcI4())
continue;
if (!instrs[i + 3].IsStloc())
continue;
key0 = (byte)ldci4.GetLdcI4Value();
return true;
}
key0 = 0;
return false;
}
static bool FindKey0_v18_r75369(MethodDef method, out byte key0) {
var instrs = method.Body.Instructions;
for (int index = 0; index < instrs.Count; index++) {
index = ConfuserUtils.FindCallMethod(instrs, index, Code.Callvirt, "System.Int32 System.IO.Stream::Read(System.Byte[],System.Int32,System.Int32)");
if (index < 0)
break;
if (index + 4 >= instrs.Count)
break;
index++;
if (instrs[index++].OpCode.Code != Code.Pop)
continue;
var ldci4 = instrs[index++];
if (!ldci4.IsLdcI4())
continue;
if (instrs[index++].OpCode.Code != Code.Conv_U1)
continue;
if (!instrs[index++].IsStloc())
continue;
key0 = (byte)ldci4.GetLdcI4Value();
return true;
}
key0 = 0;
return false;
}
static bool FindKey1_v18_r75369(MethodDef method, out byte key1) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count - 4; i++) {
int index = i;
if (!instrs[index++].IsLdloc())
continue;
var ldci4_1 = instrs[index++];
if (!ldci4_1.IsLdcI4())
continue;
if (instrs[index++].OpCode.Code != Code.Mul)
continue;
var ldci4_2 = instrs[index++];
if (!ldci4_2.IsLdcI4() || ldci4_2.GetLdcI4Value() != 0x100)
continue;
if (instrs[index++].OpCode.Code != Code.Rem)
continue;
key1 = (byte)ldci4_1.GetLdcI4Value();
return true;
}
key1 = 0;
return false;
}
static bool FindKey0Key1_v14_r55802(MethodDef method, out byte key0, out byte key1) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count - 5; i++) {
if (!instrs[i].IsLdcI4())
continue;
if (instrs[i + 1].OpCode.Code != Code.Add)
continue;
if (instrs[i + 2].OpCode.Code != Code.Ldelem_U1)
continue;
var ldci4_1 = instrs[i + 3];
if (!ldci4_1.IsLdcI4())
continue;
if (instrs[i + 4].OpCode.Code != Code.Xor)
continue;
var ldci4_2 = instrs[i + 5];
if (!ldci4_2.IsLdcI4())
continue;
key0 = (byte)ldci4_1.GetLdcI4Value();
key1 = (byte)ldci4_2.GetLdcI4Value();
return true;
}
key0 = 0;
key1 = 0;
return false;
}
static bool FindKey0_v17_r73404(MethodDef method, out byte key) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count - 3; i++) {
int index = ConfuserUtils.FindCallMethod(instrs, i, Code.Callvirt, "System.Byte[] System.IO.BinaryReader::ReadBytes(System.Int32)");
if (index < 0)
break;
if (index + 3 >= instrs.Count)
break;
if (!instrs[index + 1].IsStloc())
continue;
var ldci4 = instrs[index + 2];
if (!ldci4.IsLdcI4())
continue;
if (!instrs[index + 3].IsStloc())
continue;
key = (byte)ldci4.GetLdcI4Value();
return true;
}
key = 0;
return false;
}
static bool FindKey1_v17_r73404(MethodDef method, out byte key) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count - 3; i++) {
var ldci4_1 = instrs[i];
if (!ldci4_1.IsLdcI4())
continue;
if (instrs[i + 1].OpCode.Code != Code.Mul)
continue;
var ldci4_2 = instrs[i + 2];
if (!ldci4_2.IsLdcI4() || ldci4_2.GetLdcI4Value() != 0x100)
continue;
if (instrs[i + 3].OpCode.Code != Code.Rem)
continue;
key = (byte)ldci4_1.GetLdcI4Value();
return true;
}
key = 0;
return false;
}
public EmbeddedResource MergeResources() {
if (resource == null)
return null;
DeobUtils.DecryptAndAddResources(module, resource.Name.String, () => DecryptResource());
var tmpResource = resource;
resource = null;
return tmpResource;
}
byte[] DecryptResource() {
switch (version) {
case ConfuserVersion.v14_r55802: return Decrypt_v14_r55802();
case ConfuserVersion.v17_r73404: return Decrypt_v17_r73404();
case ConfuserVersion.v17_r73822: return Decrypt_v17_r73404();
case ConfuserVersion.v18_r75367: return Decrypt_v18_r75367();
case ConfuserVersion.v18_r75369: return Decrypt_v18_r75367();
default: throw new ApplicationException("Unknown version");
}
}
byte[] Decrypt_v14_r55802() {
var reader = new BinaryReader(new MemoryStream(DeobUtils.Inflate(resource.GetResourceData(), true)));
var encypted = reader.ReadBytes(reader.ReadInt32());
if ((encypted.Length & 1) != 0)
throw new ApplicationException("Invalid resource data length");
var decrypted = new byte[encypted.Length / 2];
for (int i = 0; i < decrypted.Length; i++)
decrypted[i] = (byte)((encypted[i * 2 + 1] ^ key0) * key1 + (encypted[i * 2] ^ key0));
reader = new BinaryReader(new MemoryStream(DeobUtils.Inflate(decrypted, true)));
return reader.ReadBytes(reader.ReadInt32());
}
byte[] Decrypt_v17_r73404() {
var reader = new BinaryReader(new MemoryStream(DeobUtils.Inflate(resource.GetResourceData(), true)));
var decrypted = reader.ReadBytes(reader.ReadInt32());
byte k = key0;
for (int i = 0; i < decrypted.Length; i++) {
decrypted[i] ^= k;
k *= key1;
}
return decrypted;
}
byte[] Decrypt_v18_r75367() {
var encrypted = resource.GetResourceData();
byte k = key0;
for (int i = 0; i < encrypted.Length; i++) {
encrypted[i] ^= k;
k *= key1;
}
var reader = new BinaryReader(new MemoryStream(DeobUtils.Inflate(encrypted, true)));
return reader.ReadBytes(reader.ReadInt32());
}
public void Deobfuscate(Blocks blocks) {
if (blocks.Method != installMethod)
return;
ConfuserUtils.RemoveResourceHookCode(blocks, handler);
}
public bool GetRevisionRange(out int minRev, out int maxRev) {
switch (version) {
case ConfuserVersion.Unknown:
minRev = maxRev = 0;
return false;
case ConfuserVersion.v14_r55802:
minRev = 55802;
maxRev = 72989;
return true;
case ConfuserVersion.v17_r73404:
minRev = 73404;
maxRev = 73791;
return true;
case ConfuserVersion.v17_r73822:
minRev = 73822;
maxRev = 75349;
return true;
case ConfuserVersion.v18_r75367:
minRev = 75367;
maxRev = 75367;
return true;
case ConfuserVersion.v18_r75369:
minRev = 75369;
maxRev = int.MaxValue;
return true;
default: throw new ApplicationException("Invalid version");
}
}
}
}