/*
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.IO;
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Confuser {
class MemoryMethodsDecrypter : MethodsDecrypterBase {
ConfuserVersion version = ConfuserVersion.Unknown;
enum ConfuserVersion {
Unknown,
v14_r57884,
v14_r58004,
v14_r58564,
v14_r58852,
v15_r59014,
v16_r71742,
v17_r72989,
// Removed in Confuser 1.7 r73404 and restored in Confuser 1.7 r73605
v17_r73605,
v18_r75288,
v19_r75725,
}
public MemoryMethodsDecrypter(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator)
: base(module, simpleDeobfuscator) {
}
public MemoryMethodsDecrypter(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator, MemoryMethodsDecrypter other)
: base(module, simpleDeobfuscator, other) {
if (other != null)
this.version = other.version;
}
protected override bool CheckType(TypeDef type, MethodDef initMethod) {
if (type == null)
return false;
if (type.Methods.Count != 3)
return false;
var virtProtect = DotNetUtils.GetPInvokeMethod(type, "kernel32", "VirtualProtect");
if (virtProtect == null)
return false;
if (!DotNetUtils.HasString(initMethod, "Broken file"))
return false;
if ((decryptMethod = FindDecryptMethod(type)) == null)
return false;
bool callsFileStreamCtor = DotNetUtils.CallsMethod(initMethod, "System.Void System.IO.FileStream::.ctor(System.String,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)");
if (!DotNetUtils.HasString(initMethod, "Module error"))
version = ConfuserVersion.v14_r57884;
else if (virtProtect.IsPrivate && callsFileStreamCtor) {
int calls = ConfuserUtils.CountCalls(initMethod, "System.Void System.Buffer::BlockCopy(System.Array,System.Int32,System.Array,System.Int32,System.Int32)");
if (calls <= 1)
version = ConfuserVersion.v14_r58564;
else if (calls == 2)
version = ConfuserVersion.v14_r58852;
else if (calls == 4)
version = ConfuserVersion.v15_r59014;
else
return false;
}
else if (callsFileStreamCtor)
version = ConfuserVersion.v14_r58004;
else if (DotNetUtils.CallsMethod(initMethod, "System.Int32 System.Object::GetHashCode()")) {
if (DotNetUtils.HasString(initMethod, ""))
version = ConfuserVersion.v17_r72989;
else
version = ConfuserVersion.v16_r71742;
}
else if (DotNetUtils.CallsMethod(decryptMethod, "System.Security.Cryptography.Rijndael System.Security.Cryptography.Rijndael::Create()"))
version = ConfuserVersion.v17_r73605;
else if (DotNetUtils.HasString(initMethod, ""))
version = ConfuserVersion.v18_r75288;
else
version = ConfuserVersion.v19_r75725;
return true;
}
public void Initialize() {
if (initMethod == null)
return;
if (!InitializeKeys())
throw new ApplicationException("Could not find all decryption keys");
}
bool InitializeKeys() {
switch (version) {
case ConfuserVersion.v14_r57884:
case ConfuserVersion.v14_r58004:
return true;
case ConfuserVersion.v14_r58564:
case ConfuserVersion.v14_r58852:
case ConfuserVersion.v15_r59014:
return InitializeKeys_v14_r58564();
case ConfuserVersion.v16_r71742:
case ConfuserVersion.v17_r72989:
return InitializeKeys_v16_r71742();
case ConfuserVersion.v17_r73605:
case ConfuserVersion.v18_r75288:
case ConfuserVersion.v19_r75725:
return InitializeKeys_v17_r73605();
default:
throw new ApplicationException("Unknown version");
}
}
bool InitializeKeys_v14_r58564() {
simpleDeobfuscator.Deobfuscate(initMethod);
if (!FindLKey0(initMethod, out lkey0))
return false;
if (!FindKey0_v14_r58564(initMethod, out key0))
return false;
if (!FindKey2Key3(initMethod, out key2, out key3))
return false;
if (!FindKey4(initMethod, out key4))
return false;
if (!FindKey5(initMethod, out key5))
return false;
simpleDeobfuscator.Deobfuscate(decryptMethod);
if (!FindKey6(decryptMethod, out key6))
return false;
return true;
}
bool InitializeKeys_v16_r71742() {
simpleDeobfuscator.Deobfuscate(initMethod);
if (!FindLKey0(initMethod, out lkey0))
return false;
if (!FindKey0_v16_r71742(initMethod, out key0))
return false;
if (!FindKey2Key3(initMethod, out key2, out key3))
return false;
if (!FindKey4(initMethod, out key4))
return false;
if (!FindKey5(initMethod, out key5))
return false;
simpleDeobfuscator.Deobfuscate(decryptMethod);
if (!FindKey6(decryptMethod, out key6))
return false;
return true;
}
bool InitializeKeys_v17_r73605() {
simpleDeobfuscator.Deobfuscate(initMethod);
if (!FindLKey0(initMethod, out lkey0))
return false;
if (!FindKey0_v16_r71742(initMethod, out key0))
return false;
if (!FindKey1(initMethod, out key1))
return false;
if (!FindKey2Key3(initMethod, out key2, out key3))
return false;
if (!FindKey4(initMethod, out key4))
return false;
if (!FindKey5(initMethod, out key5))
return false;
simpleDeobfuscator.Deobfuscate(decryptMethod);
if (!FindKey6(decryptMethod, out key6))
return false;
return true;
}
static bool FindKey4(MethodDef method, out uint key) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count; i++) {
i = FindCallvirtReadUInt32(instrs, i);
if (i < 0)
break;
if (i >= 2) {
if (instrs[i-2].OpCode.Code == Code.Pop)
continue;
}
if (i + 4 >= instrs.Count)
break;
var ldci4 = instrs[i + 1];
if (!ldci4.IsLdcI4())
continue;
if (instrs[i + 2].OpCode.Code != Code.Xor)
continue;
var stloc = instrs[i + 3];
if (!stloc.IsStloc())
continue;
var ldloc = instrs[i + 4];
if (!ldloc.IsLdloc())
continue;
if (ldloc.GetLocal(method.Body.Variables) != stloc.GetLocal(method.Body.Variables))
continue;
key = (uint)ldci4.GetLdcI4Value();
return true;
}
key = 0;
return false;
}
static bool FindKey5(MethodDef method, out uint key) {
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count; i++) {
i = FindCallvirtReadUInt32(instrs, i);
if (i < 0)
break;
int index2 = ConfuserUtils.FindCallMethod(instrs, i, Code.Callvirt, "System.Int32 System.IO.BinaryReader::ReadInt32()");
if (index2 < 0)
break;
if (index2 - i != 6)
continue;
var ldci4 = instrs[i + 1];
if (!ldci4.IsLdcI4())
continue;
if (instrs[i + 2].OpCode.Code != Code.Xor)
continue;
var stloc = instrs[i + 3];
if (!stloc.IsStloc())
continue;
var ldloc = instrs[i + 4];
if (!ldloc.IsLdloc())
continue;
if (ldloc.GetLocal(method.Body.Variables) == stloc.GetLocal(method.Body.Variables))
continue;
if (!instrs[i + 5].IsLdloc())
continue;
key = (uint)ldci4.GetLdcI4Value();
return true;
}
key = 0;
return false;
}
public bool Decrypt(MyPEImage peImage, byte[] fileData) {
if (initMethod == null)
return false;
switch (version) {
case ConfuserVersion.v14_r57884: return Decrypt_v14_r57884(peImage, fileData);
case ConfuserVersion.v14_r58004: return Decrypt_v14_r58004(peImage, fileData);
case ConfuserVersion.v14_r58564: return Decrypt_v14_r58004(peImage, fileData);
case ConfuserVersion.v14_r58852: return Decrypt_v14_r58004(peImage, fileData);
case ConfuserVersion.v15_r59014: return Decrypt_v15_r59014(peImage, fileData);
case ConfuserVersion.v16_r71742: return Decrypt_v16_r71742(peImage, fileData);
case ConfuserVersion.v17_r72989: return Decrypt_v16_r71742(peImage, fileData);
case ConfuserVersion.v17_r73605: return Decrypt_v17_r73605(peImage, fileData);
case ConfuserVersion.v18_r75288: return Decrypt_v17_r73605(peImage, fileData);
case ConfuserVersion.v19_r75725: return Decrypt_v17_r73605(peImage, fileData);
default: throw new ApplicationException("Unknown version");
}
}
bool Decrypt_v14_r57884(MyPEImage peImage, byte[] fileData) {
methodsData = DecryptMethodsData_v14_r57884(peImage, false);
var reader = new BinaryReader(new MemoryStream(methodsData));
reader.ReadInt16(); // sig
var writer = new BinaryWriter(new MemoryStream(fileData));
int numInfos = reader.ReadInt32();
for (int i = 0; i < numInfos; i++) {
uint rva = reader.ReadUInt32();
if (rva == 0)
continue;
writer.BaseStream.Position = peImage.RvaToOffset(rva);
writer.Write(reader.ReadBytes(reader.ReadInt32()));
}
return true;
}
byte[] DecryptMethodsData_v14_r57884(MyPEImage peImage, bool hasStrongNameInfo) {
var reader = peImage.Reader;
reader.Position = 0;
var md5SumData = reader.ReadBytes((int)peImage.OptionalHeader.CheckSum ^ (int)key0);
int csOffs = (int)peImage.OptionalHeader.StartOffset + 0x40;
Array.Clear(md5SumData, csOffs, 4);
var md5Sum = DeobUtils.Md5Sum(md5SumData);
ulong checkSum = reader.ReadUInt64() ^ lkey0;
if (hasStrongNameInfo) {
int sn = reader.ReadInt32();
int snLen = reader.ReadInt32();
if (sn != 0) {
if (peImage.RvaToOffset((uint)peImage.Cor20Header.StrongNameSignature.VirtualAddress) != sn ||
peImage.Cor20Header.StrongNameSignature.Size != snLen)
throw new ApplicationException("Invalid sn and snLen");
Array.Clear(md5SumData, sn, snLen);
}
}
if (checkSum != CalcChecksum(md5SumData))
throw new ApplicationException("Invalid checksum. File has been modified.");
var iv = reader.ReadBytes(reader.ReadInt32() ^ (int)key2);
var encrypted = reader.ReadBytes(reader.ReadInt32() ^ (int)key3);
var decrypted = Decrypt(encrypted, iv, md5SumData);
if (BitConverter.ToInt16(decrypted, 0) != 0x6FD6)
throw new ApplicationException("Invalid magic");
return decrypted;
}
bool Decrypt_v14_r58004(MyPEImage peImage, byte[] fileData) {
methodsData = DecryptMethodsData_v14_r57884(peImage, false);
return DecryptImage_v14_r58004(peImage, fileData);
}
bool DecryptImage_v14_r58004(MyPEImage peImage, byte[] fileData) {
var reader = new BinaryReader(new MemoryStream(methodsData));
reader.ReadInt16(); // sig
var writer = new BinaryWriter(new MemoryStream(fileData));
int numInfos = reader.ReadInt32();
for (int i = 0; i < numInfos; i++) {
uint offs = reader.ReadUInt32() ^ key4;
if (offs == 0)
continue;
uint rva = reader.ReadUInt32() ^ key4;
if (peImage.RvaToOffset(rva) != offs)
throw new ApplicationException("Invalid offs & rva");
writer.BaseStream.Position = peImage.RvaToOffset(rva);
writer.Write(reader.ReadBytes(reader.ReadInt32()));
}
return true;
}
bool Decrypt_v15_r59014(MyPEImage peImage, byte[] fileData) {
methodsData = DecryptMethodsData_v14_r57884(peImage, true);
return DecryptImage_v14_r58004(peImage, fileData);
}
bool Decrypt_v16_r71742(MyPEImage peImage, byte[] fileData) {
methodsData = DecryptMethodsData_v16_r71742(peImage, GetEncryptedHeaderOffset_v16_r71742(peImage.Sections));
return DecryptImage_v16_r71742(peImage, fileData);
}
bool Decrypt_v17_r73605(MyPEImage peImage, byte[] fileData) {
if (peImage.OptionalHeader.CheckSum == 0)
return false;
methodsData = DecryptMethodsData_v17_r73404(peImage);
return DecryptImage_v16_r71742(peImage, fileData);
}
bool DecryptImage_v16_r71742(MyPEImage peImage, byte[] fileData) {
var reader = new BinaryReader(new MemoryStream(methodsData));
reader.ReadInt16(); // sig
int numInfos = reader.ReadInt32();
for (int i = 0; i < numInfos; i++) {
uint offs = reader.ReadUInt32() ^ key4;
if (offs == 0)
continue;
uint rva = reader.ReadUInt32() ^ key5;
if (peImage.RvaToOffset(rva) != offs)
throw new ApplicationException("Invalid offs & rva");
int len = reader.ReadInt32();
for (int j = 0; j < len; j++)
fileData[offs + j] = reader.ReadByte();
}
return true;
}
public override bool GetRevisionRange(out int minRev, out int maxRev) {
switch (version) {
case ConfuserVersion.Unknown:
minRev = maxRev = 0;
return false;
case ConfuserVersion.v14_r57884:
minRev = 57884;
maxRev = 57884;
return true;
case ConfuserVersion.v14_r58004:
minRev = 58004;
maxRev = 58446;
return true;
case ConfuserVersion.v14_r58564:
minRev = 58564;
maxRev = 58817;
return true;
case ConfuserVersion.v14_r58852:
minRev = 58852;
maxRev = 58919;
return true;
case ConfuserVersion.v15_r59014:
minRev = 59014;
maxRev = 70489;
return true;
case ConfuserVersion.v16_r71742:
minRev = 71742;
maxRev = 72868;
return true;
case ConfuserVersion.v17_r72989:
minRev = 72989;
maxRev = 72989;
return true;
case ConfuserVersion.v17_r73605:
minRev = 73605;
maxRev = 75267;
return true;
case ConfuserVersion.v18_r75288:
minRev = 75288;
maxRev = 75720;
return true;
case ConfuserVersion.v19_r75725:
minRev = 75725;
maxRev = int.MaxValue;
return true;
default: throw new ApplicationException("Invalid version");
}
}
}
}