Despite Sony's best efforts, the UMD format has been
cracked. Using a combination of insecure firmware and
reverse engineering, the Sony PSP can now use a variety of homebrew
games, and legally backed up games or illegally downloaded ISOs.
Each disc uses a file system whose format follows the ISO 9660
standard. The ISO image can then be stored on a Memory Stick, and
run via a special disc emulator program. The ISO images cannot be
burned to UMD discs as UMD writables and burners are not
available.
Sony has attempted to halt this type of exploitation by updating
the firmware. Versions 1.51 and later of the PSP firmware have
attempted to patch the exploit. Recent games also come with a
'software switch' that force users to update before the game can be
played. This has also been circumvented: some applications for 1.50
report the firmware version as being more recent than it actually
is,or firmware spoofing, bypassing the need to update. This has
since been fixed by Sony and no longer works. Firmware versions 2.0
to 3.10 have been decrypted and converted into custom firmwares.
These firmwares allow people to run ISOs that they own from their
XMB interface in addition to other homebrew available.
As of August 2005, the first batch of pirated UMD ISOs have
reportedly been seen in Hong Kong for as little as HK $20 (less
than US$3, 2 or £1.50).
