You can use grep
anyway to search through the file – it does not really care if the input file is really text or not. From ‘man grep’:
-a, --text
Process a binary file as if it were text; this is equivalent to the --binary-files=text option.
--binary-files=TYPE
If the first few bytes of a file indicate that the file contains binary data, assume that the file is
of type TYPE. By default, TYPE is binary, and grep normally outputs either a one-line message saying
that a binary file matches, or no message if there is no match. If TYPE is without-match, grep assumes
that a binary file does not match; this is equivalent to the -I option. If TYPE is text, grep
processes a binary file as if it were text; this is equivalent to the -a option. Warning: grep
--binary-files=text might output binary garbage, which can have nasty side effects if the output is a
terminal and if the terminal driver interprets some of it as commands.
Please mark the words of caution at the end of the second paragraph. You might want to redirect the results from grep into a new file and examine this with vi / less.