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→FIRM-package System Modules
When a path ending in ".nsp" is parsed by MountCode, the PFS0 is treated as a raw ExeFS. Because there is no NCA header, the ACID signatures are not validated -- and because there are no other signatures in a PFS0, this results in no signature checking happening at all.
When a path ending in ".nsp" is parsed by MountCode, the PFS0 is treated as a raw ExeFS. Because there is no NCA header, the ACID signatures are not validated -- and because there are no other signatures in a PFS0, this results in no signature checking happening at all.
The actual .nsp handling is eventually done by {content mounting function} called by MountCode and other FS commands.
Thus, by placing an ExeFS (NSOs + "main.npdm") and setting one's desired title ID to "@Sdcard:/some_title.nsp" or "@User:/some_title.nsp" etc one can launch arbitrary unsigned code, with arbitrary unsigned NPDMs.
Thus, by placing an ExeFS (NSOs + "main.npdm") and setting one's desired title ID to "@Sdcard:/some_title.nsp" or "@User:/some_title.nsp" etc one can launch arbitrary unsigned code, with arbitrary unsigned NPDMs.