DumpedMethods createDumpedMethods(PeImage peImage, byte[] fileData, byte[] methodsData)
{
var dumpedMethods = new DumpedMethods();
var methodsDataReader = new BinaryReader(new MemoryStream(methodsData));
var fileDataReader = new BinaryReader(new MemoryStream(fileData));
var metadataTables = peImage.Cor20Header.createMetadataTables();
var methodDef = metadataTables.getMetadataType(MetadataIndex.iMethodDef);
uint methodDefOffset = methodDef.fileOffset;
for (int i = 0; i < methodDef.rows; i++, methodDefOffset += methodDef.totalSize) {
uint bodyRva = peImage.offsetReadUInt32(methodDefOffset);
if (bodyRva == 0)
continue;
uint bodyOffset = peImage.rvaToOffset(bodyRva);
var dm = new DumpedMethod();
dm.token = (uint)(0x06000001 + i);
dm.mdImplFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[1].offset);
dm.mdFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[2].offset);
dm.mdName = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[3].offset, methodDef.fields[3].size);
dm.mdSignature = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[4].offset, methodDef.fields[4].size);
dm.mdParamList = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[5].offset, methodDef.fields[5].size);
byte b = peImage.offsetReadByte(bodyOffset);
uint codeOffset;
if ((b & 3) == 2) {
if (b != 2)
continue; // not zero byte code size
dm.mhFlags = 2;
dm.mhMaxStack = 8;
dm.mhLocalVarSigTok = 0;
codeOffset = bodyOffset + 1;
}
else {
if (peImage.offsetReadUInt32(bodyOffset + 4) != 0)
continue; // not zero byte code size
dm.mhFlags = peImage.offsetReadUInt16(bodyOffset);
dm.mhMaxStack = peImage.offsetReadUInt16(bodyOffset + 2);
dm.mhLocalVarSigTok = peImage.offsetReadUInt32(bodyOffset + 8);
codeOffset = bodyOffset + (uint)(dm.mhFlags >> 12) * 4;
}
fileDataReader.BaseStream.Position = codeOffset;
if (!decrypter.decrypt(fileDataReader, dm))
continue;
dumpedMethods.add(dm);
}
return dumpedMethods;
}
int getStartOffset(PeImage peImage)
{
int minOffset = int.MaxValue;
foreach (var rva in mainType.Rvas) {
int rvaOffs = (int)peImage.rvaToOffset((uint)rva);
if (rvaOffs < minOffset)
minOffset = rvaOffs;
}
return minOffset == int.MaxValue ? 0 : minOffset;
}
public DecrypterBase(PeImage peImage, CodeHeader codeHeader)
{
this.peImage = peImage;
this.codeHeader = codeHeader;
endOfMetadata = peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress + peImage.Cor20Header.metadataDirectory.size);
}
public bool decrypt(PeImage peImage, ref DumpedMethods dumpedMethods)
{
this.peImage = peImage;
uint offset = peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress + peImage.Cor20Header.metadataDirectory.size);
if (!readCodeHeader(offset))
return false;
var metadataTables = peImage.Cor20Header.createMetadataTables();
var methodDefTable = metadataTables.getMetadataType(PE.MetadataIndex.iMethodDef);
if (methodDefTable.totalSize != codeHeader.methodDefElemSize)
return false;
var methodInfos = getMethodInfos(offset + 0x30 + codeHeader.totalCodeSize);
offset = methodDefTable.fileOffset - methodDefTable.totalSize;
foreach (var methodInfo in methodInfos) {
offset += methodDefTable.totalSize;
if (methodInfo.flags == 0 || methodInfo.codeOffs == 0)
continue;
uint rva = peImage.offsetReadUInt32(offset);
peImage.writeUint16(rva, (ushort)methodInfo.flags);
peImage.writeUint32(rva + 8, methodInfo.localVarSigTok);
}
dumpedMethods = new DumpedMethods();
offset = methodDefTable.fileOffset;
for (int i = 0; i < methodInfos.Count; i++, offset += methodDefTable.totalSize) {
var methodInfo = methodInfos[i];
if (methodInfo.codeOffs == 0)
continue;
var dm = new DumpedMethod();
dm.token = 0x06000001 + (uint)i;
uint rva = peImage.offsetReadUInt32(offset);
dm.mdImplFlags = peImage.offsetReadUInt16(offset + (uint)methodDefTable.fields[1].offset);
dm.mdFlags = peImage.offsetReadUInt16(offset + (uint)methodDefTable.fields[2].offset);
dm.mdName = peImage.offsetRead(offset + (uint)methodDefTable.fields[3].offset, methodDefTable.fields[3].size);
dm.mdSignature = peImage.offsetRead(offset + (uint)methodDefTable.fields[4].offset, methodDefTable.fields[4].size);
dm.mdParamList = peImage.offsetRead(offset + (uint)methodDefTable.fields[5].offset, methodDefTable.fields[5].size);
dm.code = decrypter.decrypt(methodInfo);
if ((peImage.readByte(rva) & 3) == 2) {
dm.mhFlags = 2;
dm.mhMaxStack = 8;
dm.mhCodeSize = (uint)dm.code.Length;
dm.mhLocalVarSigTok = 0;
}
else {
dm.mhFlags = peImage.readUInt16(rva);
dm.mhMaxStack = peImage.readUInt16(rva + 2);
dm.mhCodeSize = (uint)dm.code.Length;
dm.mhLocalVarSigTok = peImage.readUInt32(rva + 8);
}
dumpedMethods.add(dm);
}
return true;
}
public MethodInfos(MainType mainType, PeImage peImage, PeHeader peHeader, McHeader mcHeader)
{
this.mainType = mainType;
this.peImage = peImage;
this.peHeader = peHeader;
this.mcHeader = mcHeader;
structSize = getStructSize(mcHeader);
uint methodInfosRva = peHeader.getRva2(0x0FF8, mcHeader.readUInt32(0x005A));
uint encryptedDataRva = peHeader.getRva2(0x0FF0, mcHeader.readUInt32(0x0046));
methodInfosOffset = peImage.rvaToOffset(methodInfosRva);
encryptedDataOffset = peImage.rvaToOffset(encryptedDataRva);
}
void decryptResources(byte[] fileData, PeImage peImage, PeHeader peHeader, McHeader mcHeader)
{
uint resourceRva = peHeader.getRva1(0x0E10, mcHeader.readUInt32(0x00A0));
uint resourceSize = peHeader.readUInt32(0x0E14) ^ mcHeader.readUInt32(0x00AA);
if (resourceRva == 0 || resourceSize == 0)
return;
if (resourceRva != peImage.Cor20Header.resources.virtualAddress ||
resourceSize != peImage.Cor20Header.resources.size) {
Log.w("Invalid resource RVA and size found");
}
Log.v("Decrypting resources @ RVA {0:X8}, {1} bytes", resourceRva, resourceSize);
int resourceOffset = (int)peImage.rvaToOffset(resourceRva);
for (int i = 0; i < resourceSize; i++)
fileData[resourceOffset + i] ^= mcHeader[i % 0x2000];
}
DumpedMethods decryptMethods(PeImage peImage, PeHeader peHeader, McHeader mcHeader)
{
var dumpedMethods = new DumpedMethods();
var methodInfos = new MethodInfos(mainType, peImage, peHeader, mcHeader);
methodInfos.initializeInfos();
var metadataTables = peImage.Cor20Header.createMetadataTables();
var methodDef = metadataTables.getMetadataType(MetadataIndex.iMethodDef);
uint methodDefOffset = methodDef.fileOffset;
for (int i = 0; i < methodDef.rows; i++, methodDefOffset += methodDef.totalSize) {
uint bodyRva = peImage.offsetReadUInt32(methodDefOffset);
if (bodyRva == 0)
continue;
var info = methodInfos.lookup(bodyRva);
if (info == null)
continue;
uint bodyOffset = peImage.rvaToOffset(bodyRva);
ushort magic = peImage.offsetReadUInt16(bodyOffset);
if (magic != 0xFFF3)
continue;
var dm = new DumpedMethod();
dm.token = (uint)(0x06000001 + i);
dm.mdImplFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[1].offset);
dm.mdFlags = peImage.offsetReadUInt16(methodDefOffset + (uint)methodDef.fields[2].offset);
dm.mdName = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[3].offset, methodDef.fields[3].size);
dm.mdSignature = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[4].offset, methodDef.fields[4].size);
dm.mdParamList = peImage.offsetRead(methodDefOffset + (uint)methodDef.fields[5].offset, methodDef.fields[5].size);
var reader = new BinaryReader(new MemoryStream(info.body));
byte b = reader.ReadByte();
if ((b & 3) == 2) {
dm.mhFlags = 2;
dm.mhMaxStack = 8;
dm.mhCodeSize = (uint)(b >> 2);
dm.mhLocalVarSigTok = 0;
}
else {
reader.BaseStream.Position--;
dm.mhFlags = reader.ReadUInt16();
dm.mhMaxStack = reader.ReadUInt16();
dm.mhCodeSize = reader.ReadUInt32();
dm.mhLocalVarSigTok = reader.ReadUInt32();
uint codeOffset = (uint)(dm.mhFlags >> 12) * 4;
reader.BaseStream.Position += codeOffset - 12;
}
dm.code = reader.ReadBytes((int)dm.mhCodeSize);
if ((dm.mhFlags & 8) != 0) {
reader.BaseStream.Position = (reader.BaseStream.Position + 3) & ~3;
dm.extraSections = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
}
dumpedMethods.add(dm);
}
return dumpedMethods;
}
