A HACKER's Security Guide — César Cerrudo

Who is it for?

This book is for you if...

You use the internet every day

And you want to know how to protect your personal information, your accounts, and your privacy without being a tech expert.

You have a family

And you want to protect your children from cyberbullying, grooming, sexting, and other threats minors face online.

You own a business

And you want to prevent a cyberattack from destroying years of work, customer data, and your company's reputation.

You're a teacher or professional

And you want to understand current threats in order to pass on good digital security practices to others.

The book

What will you find?

Written from the real perspective of a hacker, this guide will show you how attackers think, how they exploit everyday mistakes, and why the biggest risk is often not technology, but trust.

No unnecessary jargon, with clear examples:

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Protect your family

Practical advice to keep your loved ones safe in a hyperconnected world. Includes sections dedicated to protecting children.

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Avoid fraud and scams

Learn to identify and dodge scams, digital manipulation, and social engineering techniques before falling for them.

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Take back control

Concrete tools and strategies to navigate an increasingly hostile digital environment with confidence.

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Defend yourself from AI

Understand the dangers of deepfakes, voice cloning, AI-powered phishing, and how to recognize them.

It's not a book for experts.

It's a book for those who don't want to be victims.

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CESAR_CERRUDOPROFESSIONAL_HACKER

Author

César Cerrudo

Professional Hacker · Cybersecurity Researcher

César Cerrudo has been a professional hacker for more than 25 years, carrying out a wide range of work and research in cybersecurity. He has helped many companies —Microsoft, Oracle, Twitter, IBM, and many others— protect their technologies by identifying hundreds of security issues affecting millions of people.

He has presented the results of his research at major companies and conferences around the world. His work has also been covered by leading international media outlets such as The New York Times, Time, Bloomberg Businessweek, The Guardian, CNN, NBC, Fox News, Financial Times, and The Wall Street Journal, among others.

He achieved worldwide fame for hacking the traffic lights of New York City. He is currently a cybersecurity advisor for companies, institutions, and governments, and is also the CEO of Argeniss Software.

Contents

10 essential chapters

From protecting passwords and Wi-Fi networks to understanding the dangers of artificial intelligence, cryptocurrencies, and deepfakes, the book covers everything you need to know to navigate the digital world safely.

Hover or tap each chapter to see what it covers.

Contents

01Cybersecurity in everyday lifeWhy everyone is a target today: how the threat landscape changed and what's really at stake.
02Living with dangers on the internetThe everyday risks of browsing, shopping and chatting online, and how to lower your exposure without giving up the internet.
03Access passwordsHow to create and manage passwords that withstand attacks, adding a second factor (MFA) and passkeys.
04Protecting phones and mobile devicesYour phone knows everything about you: how to harden it against theft, spying and the dangerous SIM swapping.
05Cryptocurrencies and blockchainWhat they really are, what risks they carry, and how to avoid scams and losses with no way back.
06Practical tips for everyday lifeSimple habits and security routines that make a real difference without being an expert.
07Advice for parents and educatorsHow to protect minors from grooming, cyberbullying and other risks, and how to talk to them.
08What to do if we get hackedThe step-by-step protocol to react fast and limit the damage when something goes wrong.
09Artificial intelligenceDeepfakes, voice cloning and AI-powered phishing: the new threats and how to recognize them.
10(Not so) future threatsWhat's coming —quantum computing and more— and why it's worth getting ready today.

Testimonials

What people say about the guide

An essential guide that translates the complexity of cybersecurity into advice anyone can apply today.

Featured readers

Cybersecurity community

César Cerrudo is not a cybercriminal; he is a hacker who has helped fix security flaws at major companies and organizations.

Chema Alonso

Hacker, former Telefónica Executive Committee, foreword author

The book covers everything from the essentials to emerging threats like deepfakes and quantum computing, with anecdotes that make it all much more real and tangible.

Early readers

Early reviews

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Resources

Free tools to protect yourself

Beyond the book, there is free companion material to put what you learn into practice:

Quiz: How hackable are you?

Answer a few quick questions about your digital habits and find out your level of exposure, with tips to improve it.

Take the quiz →

Digital Security Academy

Short, interactive lessons to learn to defend yourself the way a hacker thinks, with challenges and a final certification.

Start learning →

Simulator: Real or scam?

Train your eye with 18 real and fraudulent messages. Can you spot the traps before clicking?

Enter the simulator →

Downloadable infographics

8 one-page visual guides with the essentials of each topic, ready to print, save or share via WhatsApp.

Download →

Kit for workshops and classes

Ready-to-use material to give talks at companies, schools and communities: presentations, guides and activity sheets.

Download the kit →

See all resources →

FAQ

Frequently asked questions

Is the book really free?

Yes. The guide is distributed for free in digital format. You can download it without registering or paying anything.

What formats is it available in?

PDF and Epub, compatible with any computer, tablet, phone or e-reader. It is available in Spanish, English and Portuguese.

Do I need technical knowledge to understand it?

No. It is written for everyone, without unnecessary jargon and with clear examples from everyday life. If you use a phone or the internet, you will understand it.

Is there a print edition?

There is no print edition for sale at the moment, but thanks to its open license you can print the book yourself if you wish. If you are interested in an official print edition, subscribe to the newsletter to hear about the news.

Can I share it with others?

Yes, please do! Share it with your family, friends and colleagues. The more people know how to protect themselves, the harder the scammers' job gets.

What license is the book distributed under?

The book is distributed under the Creative Commons Attribution 4.0 (CC BY 4.0) license. This means you can freely copy, use, distribute and even print it if you wish, as long as you give proper credit to the author.

Is there more material besides the book?

Yes. In the Resources section you will find an interactive quiz to measure how exposed you are, the Digital Security Academy with practical lessons, the Real or scam? simulator to train your eye against scams, and downloadable infographics to print and share. All free and under the same open license as the book.

A Hacker'sSecurity Guide