Today, we share a lot of personal data online. Our names, phone numbers, credit card details, even where we live or work. Companies are supposed to protect that information. But sometimes, things go wrong. Hackers break in, systems fail, or companies make mistakes. And when that happens, millions, even billions of people can be affected.
In this blog, let’s discuss some of the biggest data breaches in history, what caused them, and what we can learn from each one, in plain, simple English.
Let’s start with the biggest one ever, Yahoo. Back in 2013 and 2014, hackers broke into Yahoo’s systems. But Yahoo didn’t tell the public until 2016. At first, they said 1 billion accounts were affected, but later they admitted it was actually 3 billion accounts, that’s basically every Yahoo user at the time.
The hackers got names, emails, phone numbers, dates of birth, and even answers to security questions like “What’s your pet’s name?”
This breach happened in Marriott’s guest reservation system. What makes this one scary is that the hackers were inside the system for four years before anyone noticed. They were able to collect personal and travel information for half a billion guests.
This happened after Marriott bought another hotel chain (Starwood), and the old system had weak security. Hackers had already broken into Starwood before the buyout, and they just stayed in the system even after Marriott took over.
Equifax is a credit reporting agency. They store a lot of private financial information about people. In 2017, they got hacked because of something very simple, they didn’t install a software update. Hackers used that weakness to get in and steal highly sensitive personal data.
This breach hit hard because the stolen info could easily be used for identity theft. Imagine someone using your Social Security number to open a bank account in your name.
This wasn’t a traditional hack. No one broke into LinkedIn’s servers. Instead, hackers scraped public data using LinkedIn’s own tools and APIs. That means they used automated software to collect public profile information from millions of users.
Even though the data was public, when it’s collected on such a large scale, it becomes a big privacy concern. That information was later found on hacker forums.
Hackers got into Target’s system through something unexpected, a heating and cooling vendor. That vendor had access to Target’s network for maintenance purposes. Once hackers stole the vendor’s login, they were in.
They installed malware on payment machines inside Target stores and stole credit card information from about 40 million people. Later, personal details of another 70 million customers were also found to be exposed.
Hackers exploited a Facebook feature that let users find friends using phone numbers. They abused it to pull out private data and posted it online.
Facebook said they fixed the feature back in 2019, but the leaked data had already spread.
Hackers broke into Adobe and stole login details of over 150 million users. The passwords were encrypted but the encryption wasn’t strong enough. Many passwords were easily cracked. Even worse, Adobe had stored password hints in plain text, making it easier for hackers.
These breaches show us something important: cybersecurity isn’t just an IT issue. It’s a business issue.
Sometimes it’s a missed update. Other times, it’s an old system no one checked. Or it’s a small feature that got overlooked. But the damage? That’s huge. Lost trust. Lost money. Legal trouble. And long-term harm to the company’s reputation.
Here’s what every company should do:
Data breaches can cost your business more than just money, they damage trust, disrupt operations, and create long-term risk. At Sattrix, we help organizations stay one step ahead with proactive cybersecurity solutions, 24/7 monitoring, and expert incident response.
The biggest data breach in history was the Yahoo breach in 2013–2014, where 3 billion user accounts were affected. Hackers stole names, email addresses, phone numbers, dates of birth, and security questions. It was later revealed that nearly every Yahoo user was impacted.
One of the biggest data breaches in India was the Aadhaar data leak in 2018. Reports suggested that personal data of over 1.1 billion Indian citizens was exposed through unauthorized access. This included Aadhaar numbers, names, addresses, phone numbers, and more. The breach raised serious concerns about national data privacy.
Google has not experienced a massive, confirmed data breach like some other major companies. However, in 2018, Google did shut down Google+ after discovering a security flaw that may have exposed the personal data of over 500,000 users. While it wasn’t a full-scale breach, it was a significant privacy incident.
While banks don’t always reveal detailed data breach info, JPMorgan Chase is one of the most high-profile banks hit by a cyberattack. In 2014, a breach affected 76 million households and 7 million small businesses. Attackers gained access to names, emails, phone numbers, and addresses. Since then, many banks worldwide have faced frequent hacking attempts, especially through phishing and ransomware.
