What is the use of epsec-package file in APM ?

F5 client side controls rely on software developed by a 3rd party provider called OPSWAT (you can look for their website), and the EPSEC package is their software included with APM. 

You rarely need to interact directly with these settings. F5 APM, if the client side agent is added to the VPE, will manage the interaction between epsec and user's machine on your behalf