[22:01:55.40] C:\test>perl -pe "s/\x00\x42\x00\x11/\x00\x42\x00\xf0/sg" 834245.masks >junk.dat

[22:06:46.76] C:\test>perl -pe "s/\x00\x42\x00\x11/\x00\x42\x00\xf0/sg" 834245.masks >junk.dat

[22:09:31.99] C:\test>