NAME

       Imager::Security - brief notes on security and image processing

SYNOPSIS

         # keep abreast of security updates
         apt-get update && apt-get upgrade
         yum upgrade
         pkgin update && pkgin upgrade
         # or local equivalent

         # limit memory use
         use Imager;
         # only images that use up to 10MB
         Imager->set_file_limits(bytes => 10_000_000);

DESCRIPTION

       There's two basic security considerations when dealing with images from an unknown source:

       •   keeping your libraries up to date

       •   limiting the amount of memory used to store images

   Keeping libraries up to date
       Image file format libraries such as "libpng" or "libtiff" have relatively frequent
       security updates, keeping your libraries up to date is basic security.

       If you're using user supplied fonts, you will need to keep your font libraries up to date
       too.

   Limiting memory used
       With compression, and especially with pointer formats like TIFF, it's possible to store
       very large images in a relatively small file.

       If you're receiving image data from an untrusted source you should limit the amount of
       memory that Imager can allocate for a read in image file using the "set_file_limits()"
       method.

         Imager->set_file_limits(bytes => 10_000_000);

       You may also want to limit the maximum width and height of images read from files:

         Imager->set_file_limits(width => 10_000, height => 10_000,
                                 bytes => 10_000_000);

       This has no effect on images created without a file:

         # succeeds
         my $image = Imager->new(xsize => 10_001, ysize => 10_001);

       You can reset to the defaults with:

         Imager->set_file_limits(reset => 1);

AUTHOR

       Tony Cook <tonyc@cpan.org>