If you can change the password to a known string, change it to "password" (or something simple), convert the base64 into the more common hex formatting with a command like this:
$ echo 'KGdV+tBIacpSMyCszg3GpA==' | base64 -d | xxd -g16 00000000: 286755fad04869ca523320acce0dc6a4 (gU..Hi.R3 .....
Then put the string (286755fad04869ca523320acce0dc6a4) into a file and run password-cracking tools against it using any 128-bit algorithm they support:
~/tools/JohnTheRipper/run $ echo '286755fad04869ca523320acce0dc6a4' > test.hex ~/tools/JohnTheRipper/run $ ./john --format=raw-md5 ./test.hex Using default input encoding: UTF-8 Loaded 1 password hash (Raw-MD5 [MD5 256/256 AVX2 8x3]) Press 'q' or Ctrl-C to abort, almost any other key for status [.....]
If you're lucky, it's something standard and it'll just pop.
Otherwise, you might have to do some sleuthing to figure out how it's salted or whatever.