Use Flash Player after 12 Jan 2021

I managed to make the “time bomb defuser” work, as indicated here:

Disable EOL uninstall warnings:
    Disable auto updates when installing
    Add "EOLUninstallDisable=1" to mmc.cfg in C:\WINDOWS\system32\Macromed\Flash
    (C:\Windows\SysWOW64\Macromed\Flash on 64-bit)

---

Defuse flash player time bomb:

Time bomb trigger is the timestamp 1610409600000.0
encoded in double precision floating point (0x42776f3e46400000):
    00 00 40 46 3E 6F 77 42
replace with infinity:
    00 00 00 00 00 00 F8 7F

C:\WINDOWS\system32\Macromed\Flash
(C:\Windows\SysWOW64\Macromed\Flash on 64-bit)
    Flash32_32_0_0_453.ocx (offset: 453: E1D968, 465: E1DBD0)
    NPSWF32_32_0_0_453.dll (offset: 453: E3A2E0, 465: E3A32A)
    pepflashplayer32_32_0_0_453.dll (offset: 453: CBFCE0, 465: CBFCB8)

C:\WINDOWS\system32\Macromed\Flash (64-bit):
    Flash64_32_0_0_453.ocx (offset: 12AF6A8)
    NPSWF32_32_0_0_453.dll (offset: 128FBD8)
    pepflashplayer32_32_0_0_453.dll (offset: 15F6C30)

NOTE: Flash32_32_0_0_453.ocx (and Flash64) will always be write protected
    - rename it to Flash32_32_0_0_453.bak
    - save edited copy as Flash32_32_0_0_453.ocx
    - to delete the backup file:
        - properties > security > advanced > delete the "DENY Everyone" permission

Here’s what I did:

• Copy the Flash directory (C:\WINDOWS\system32\Macromed\Flash for 32-bit, C:\Windows\SysWOW64\Macromed\Flash for 64-bit) to somewhere where I have write permission;
• Use a hex editor to open Flash.ocx;
• Search for the hexadecimal string 000040463E6F7742 (the timestamp) and replace it with 000000000000F87F;
• Save the file;
• Rename the Flash directory (to avoid permission issues) to Flash.bak or something else;
• Copy the Flash directory with the modified binary to its original location.

I just tested an offline desktop application which had stopped working, and it works again.

Note: the linked page mentions mmc.cfg, but my Flash folder had a mms.cfg file instead; maybe it was a typo, but in any case I added the EOLUninstallDisable=1 line.

Note: In my case, the application using Flash works offline and should present minimal security risks. For continuous usage in a browser, I’d prefer following Tetsujin’s recommendation and try a standalone but supported Flash player, such as Newgrounds’.