// Magic!
internal byte[] Patch()
{
byte[] SecurityDxe = GetFile("SecurityDxe");
ClearEfiChecksum(SecurityDxe);
UInt32?PatchOffset = ByteOperations.FindPattern(SecurityDxe,
new byte[] { 0xF0, 0x41, 0x2D, 0xE9, 0xFF, 0xFF, 0xB0, 0xE1, 0x28, 0xD0, 0x4D, 0xE2, 0xFF, 0xFF, 0xA0, 0xE1, 0x00, 0x00, 0xFF, 0x13, 0x20, 0xFF, 0xA0, 0xE3 },
new byte[] { 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00 },
null);
if (PatchOffset == null)
{
throw new BadImageFormatException();
}
Buffer.BlockCopy(new byte[] { 0x00, 0x00, 0xA0, 0xE3, 0x1E, 0xFF, 0x2F, 0xE1 }, 0, SecurityDxe, (int)PatchOffset, 8);
ReplaceFile("SecurityDxe", SecurityDxe);
byte[] SecurityServicesDxe = GetFile("SecurityServicesDxe");
ClearEfiChecksum(SecurityServicesDxe);
PatchOffset = ByteOperations.FindPattern(SecurityServicesDxe,
new byte[] { 0x10, 0xFF, 0xFF, 0xE5, 0x80, 0xFF, 0x10, 0xE3, 0xFF, 0xFF, 0xFF, 0x0A },
new byte[] { 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x00 },
null);
if (PatchOffset == null)
{
throw new BadImageFormatException();
}
ByteOperations.WriteUInt8(SecurityServicesDxe, (UInt32)PatchOffset + 0x0B, 0xEA);
PatchOffset = ByteOperations.FindPattern(SecurityServicesDxe,
new byte[] { 0x11, 0xFF, 0xFF, 0xE5, 0x40, 0xFF, 0x10, 0xE3, 0xFF, 0xFF, 0xFF, 0x0A },
new byte[] { 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x00 },
null);
if (PatchOffset == null)
{
throw new BadImageFormatException();
}
ByteOperations.WriteUInt8(SecurityServicesDxe, (UInt32)PatchOffset + 0x0B, 0xEA);
ReplaceFile("SecurityServicesDxe", SecurityServicesDxe);
return(Rebuild());
}
private void CalculateFileChecksum(byte[] Image, UInt32 Offset)
{
UInt16 FileHeaderSize = 0x18;
UInt32 FileSize = ByteOperations.ReadUInt24(Image, Offset + 0x14);
ByteOperations.WriteUInt16(Image, Offset + 0x10, 0); // Clear checksum
byte NewChecksum = ByteOperations.CalculateChecksum8(Image, Offset, (UInt32)FileHeaderSize - 1);
ByteOperations.WriteUInt8(Image, Offset + 0x10, NewChecksum); // File-Header checksum
byte FileAttribs = ByteOperations.ReadUInt8(Image, Offset + 0x13);
if ((FileAttribs & 0x40) > 0)
{
// Calculate file checksum
byte CalculatedFileChecksum = ByteOperations.CalculateChecksum8(Image, Offset + FileHeaderSize, FileSize - FileHeaderSize);
ByteOperations.WriteUInt8(Image, Offset + 0x11, CalculatedFileChecksum);
}
else
{
// Fixed file checksum
ByteOperations.WriteUInt8(Image, Offset + 0x11, 0xAA);
}
}
