Security issues concerning including external code for module I would like to implement some external code in my custom module and if I understand correctly (correct me if I'm wrong), you can drop those folders in both sites/all/libraries as well as in sites/all/modules/custom/myModule/libraries.

What would the better security-wise place to include the folder be?  

If you can think of another reason why to place it in the first folder or the second, I'm happy to hear it.
If your web server is set up correctly then both of the paths you've mentioned will have the same permissions (readable but not writeable by the server), so they would be equally secure/insecure depending on the rest of your server setup.

I must admit I haven't come across a path like the second one you mention, although I know most contributed modules that have been updated to Drupal 7 use the sites/all/libraries folder for storing external code libraries.