/usr/lib/nagios/plugins/check_webinject is in nagios-plugins-contrib 14.20141104.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | #!/usr/bin/perl
# nagios: -epn
#    Copyright 2010 Sven Nierlein (nierlein@cpan.org)
#    Copyright 2004-2006 Corey Goldberg (corey@goldb.org)
#
#    This file is part of WebInject.
#
#    WebInject is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    WebInject is distributed in the hope that it will be useful,
#    but without any warranty; without even the implied warranty of
#    merchantability or fitness for a particular purpose.  See the
#    GNU General Public License for more details.
use warnings;
use strict;
use Webinject;
my $webinject = Webinject->new(reporttype => "nagios", timeout => 30, break_on_errors => 1);
my $rc = $webinject->engine();
exit $rc;
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