/*
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 System.IO;
using SevenZip.Compression.LZMA;
using dnlib.IO;
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Confuser {
static class ConfuserUtils {
public static int FindCallMethod(IList instrs, int index, Code callCode, string methodFullName) {
for (int i = index; i < instrs.Count; i++) {
if (!IsCallMethod(instrs[i], callCode, methodFullName))
continue;
return i;
}
return -1;
}
public static int FindCallMethod(IList instrs, int index, Code callCode, string methodFullName) {
for (int i = index; i < instrs.Count; i++) {
if (!IsCallMethod(instrs[i].Instruction, callCode, methodFullName))
continue;
return i;
}
return -1;
}
public static bool IsCallMethod(Instruction instr, Code callCode, string methodFullName) {
if (instr.OpCode.Code != callCode)
return false;
var calledMethod = instr.Operand as IMethod;
return calledMethod != null && calledMethod.FullName == methodFullName;
}
public static bool RemoveResourceHookCode(Blocks blocks, MethodDef handler) {
return RemoveResolveHandlerCode(blocks, handler, "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)");
}
public static bool RemoveAssemblyHookCode(Blocks blocks, MethodDef handler) {
return RemoveResolveHandlerCode(blocks, handler, "System.Void System.AppDomain::add_AssemblyResolve(System.ResolveEventHandler)");
}
static bool RemoveResolveHandlerCode(Blocks blocks, MethodDef handler, string installHandlerMethod) {
bool modified = false;
foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
var instrs = block.Instructions;
for (int i = 0; i < instrs.Count - 4; i++) {
var call = instrs[i];
if (call.OpCode.Code != Code.Call)
continue;
var calledMethod = call.Operand as IMethod;
if (calledMethod == null || calledMethod.FullName != "System.AppDomain System.AppDomain::get_CurrentDomain()")
continue;
if (instrs[i + 1].OpCode.Code != Code.Ldnull)
continue;
var ldftn = instrs[i + 2];
if (ldftn.OpCode.Code != Code.Ldftn)
continue;
if (ldftn.Operand != handler)
continue;
var newobj = instrs[i + 3];
if (newobj.OpCode.Code != Code.Newobj)
continue;
var ctor = newobj.Operand as IMethod;
if (ctor == null || ctor.FullName != "System.Void System.ResolveEventHandler::.ctor(System.Object,System.IntPtr)")
continue;
var callvirt = instrs[i + 4];
if (callvirt.OpCode.Code != Code.Callvirt)
continue;
calledMethod = callvirt.Operand as IMethod;
if (calledMethod == null || calledMethod.FullName != installHandlerMethod)
continue;
block.Remove(i, 5);
modified = true;
}
}
return modified;
}
public static byte[] DecryptCompressedInt32Data(Arg64ConstantsReader constReader, int exprStart, int exprEnd, IBinaryReader reader, byte[] decrypted) {
for (int i = 0; i < decrypted.Length; i++) {
constReader.Arg = reader.Read7BitEncodedInt32();
int index = exprStart;
long result;
if (!constReader.GetInt64(ref index, out result) || index != exprEnd)
throw new ApplicationException("Could not decrypt integer");
decrypted[i] = (byte)result;
}
return decrypted;
}
static readonly byte[] defaultDecryptKey = new byte[1];
public static byte[] Decrypt(uint seed, byte[] encrypted) {
return Decrypt(seed, encrypted, defaultDecryptKey);
}
public static byte[] Decrypt(uint seed, byte[] encrypted, byte[] key) {
var decrypted = new byte[encrypted.Length];
ushort _m = (ushort)(seed >> 16);
ushort _c = (ushort)seed;
ushort m = _c; ushort c = _m;
for (int i = 0; i < decrypted.Length; i++) {
decrypted[i] = (byte)(encrypted[i] ^ (seed * m + c) ^ key[i % key.Length]);
m = (ushort)(seed * m + _m);
c = (ushort)(seed * c + _c);
}
return decrypted;
}
public static int CountCalls(MethodDef method, string methodFullName) {
if (method == null || method.Body == null)
return 0;
int count = 0;
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code != Code.Call && instr.OpCode.Code != Code.Callvirt && instr.OpCode.Code != Code.Newobj)
continue;
var calledMethod = instr.Operand as IMethod;
if (calledMethod != null && calledMethod.FullName == methodFullName)
count++;
}
return count;
}
public static int CountCalls(MethodDef method, MethodDef calledMethod) {
if (method == null || method.Body == null)
return 0;
int count = 0;
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code != Code.Call && instr.OpCode.Code != Code.Callvirt && instr.OpCode.Code != Code.Newobj)
continue;
if (instr.Operand == calledMethod)
count++;
}
return count;
}
public static int CountOpCode(MethodDef method, Code code) {
if (method == null || method.Body == null)
return 0;
int count = 0;
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code == code)
count++;
}
return count;
}
public static byte[] SevenZipDecompress(byte[] data) {
var reader = new BinaryReader(new MemoryStream(data));
var props = reader.ReadBytes(5);
var decoder = new Decoder();
decoder.SetDecoderProperties(props);
long totalSize = reader.ReadInt64();
long compressedSize = data.Length - props.Length - 8;
var decompressed = new byte[totalSize];
decoder.Code(reader.BaseStream, new MemoryStream(decompressed, true), compressedSize, totalSize, null);
return decompressed;
}
// Finds the Lzma type by finding an instruction that allocates a new Lzma.Decoder
public static TypeDef FindLzmaType(MethodDef method) {
if (method == null || method.Body == null)
return null;
foreach (var instr in method.Body.Instructions) {
if (instr.OpCode.Code != Code.Newobj)
continue;
var ctor = instr.Operand as MethodDef;
if (ctor == null)
continue;
var ctorType = ctor.DeclaringType;
if (ctorType == null)
continue;
if (!IsLzmaType(ctorType.DeclaringType))
continue;
return ctorType.DeclaringType;
}
return null;
}
static bool IsLzmaType(TypeDef type) {
if (type == null)
return false;
if (type.NestedTypes.Count != 6)
return false;
if (!CheckLzmaMethods(type))
return false;
if (FindLzmaOutWindowType(type.NestedTypes) == null)
return false;
return true;
}
static bool CheckLzmaMethods(TypeDef type) {
int methods = 0;
foreach (var m in type.Methods) {
if (m.IsStaticConstructor)
continue;
if (m.IsInstanceConstructor) {
if (m.MethodSig.GetParamCount() != 0)
return false;
continue;
}
if (!DotNetUtils.IsMethod(m, "System.UInt32", "(System.UInt32)"))
return false;
methods++;
}
return methods == 1;
}
static readonly string[] outWindowFields = new string[] {
"System.Byte[]",
"System.UInt32",
"System.IO.Stream",
};
static TypeDef FindLzmaOutWindowType(IEnumerable types) {
foreach (var type in types) {
if (new FieldTypes(type).Exactly(outWindowFields))
return type;
}
return null;
}
}
}