I was a preteen hacker. Now I protect companies from cybersecurity threats.

• Chaim Mazal said he wrote a program that could generate credit card numbers when he was 12.
• Today, he's a cybersecurity executive at a company that secures complex network infrastructures.
• Mazal now uses the hacker mindset he developed as a kid to protect data from AI-driven threats.

This as-told-to essay is based on a conversation with 41-year-old Chaim Mazal, chief security officer of Gigamon, a cloud security company based in Santa Clara, California. This story has been edited for length and clarity.

I got my first computer in the early '90s when I was 8 years old and living in Florida. A few years later, I started hanging out in hacker chat rooms on a service called Internet Relay Chat. My parents had no idea.

I was very taken by the hacker community. The people in these chat rooms talked about making programs to perform various tasks. It was a large community, and we would all share information. Some people in it helped me learn how to create internet utility tools, and not all of them were so great.

For example, when I was 12, I wrote a program that could generate credit card numbers. I then used those cards to purchase commercial software and distribute it for free. It was the coolest thing that I could think of doing at the time.

I didn't get arrested, but some of my friends did. That encouraged me to change my trajectory.

How my hacking background helped me

After high school, I enrolled in a local community college to study computer science. However, I didn't finish my degree until later in life because I got an entry-level customer support job at Microsoft for one of the company's early cybersecurity offerings.

A friend who worked at a Microsoft satellite office in my area gave me a referral. I didn't mention my hacking background in the interview, but that experience helped me pass a two-hour aptitude test.

Two years later, I decided to take a career break. I hated working in a cubicle, so I went to Israel to take part in a study abroad program, with a plan to become a rabbi. But ultimately, I concluded that I didn't want to mix God and money. I moved back to the US, finished my college education, and got a job at a boutique cybersecurity firm in Chicago.

As my career progressed, I gained the opportunity to work with some of the world's best security teams. I eventually built up my own reputation as a cybersecurity expert, and began getting offers for speaking engagements and consulting work.

An attacker's mindset

I joined Gigamon, the company I work for today, three and a half years ago. We help protect some of the most complex network infrastructures in the world, including more than 80% of the Fortune 100.

It's a huge challenge. My No. 1 goal when I show up to work is to safeguard customer data. I'm trying to solve potential problems for our customers so they don't have to worry about their data ever being compromised or their identity being stolen.

If I were to give career advice to my young hacker self, I'd say you can still do what you're doing — only for good. You can provide value to the world because understanding how attackers think is essential in cybersecurity. It provides the perspective needed to stay ahead of increasingly sophisticated AI-driven threats and to build defenses that organizations can trust.

From the beginning, my intent was never about causing harm. It was about curiosity and understanding how systems worked so they could be improved. Like many in the early hacker community, I was driven by the belief that technology should be better, more secure, and more accessible.

That same mindset drives me today. The difference is scale and responsibility.