The diploma may give you a insight to the field. So you can pursue it and it will help you in some way to pursue the career in Ethical Hacking.

With 8 months Diploma , it will not help you to get a job if you have no other skills than Ethical hacking. If you have programming knowledge along with the Diploma it will suffice you a job with 90% possibility.

*The knowledge gained only from diploma will just add a highlight but with only such diploma , you won't be able to get a good job.

Have a great day!