Fastest way would be OSCP cert.
However, unlike Certified Ethical Hacker, CISSP, and other "mile wide, but inch deep" certs, the OSCP is a heavily hands-on certification that tests actual ability. No knowledgeable employer would discriminate against you for earning it.
And CISSP or CISSM are valuable if you're applying for a management job. For government defense-sector jobs, they are often required.