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  • Nick Russo

Top Five Data Breaches In The Last Five Years


Data breaches are one of the most serious threats to the security and privacy of individuals and organizations in the digital age. A data breach occurs when an unauthorized party accesses, copies, or exposes sensitive information, such as personal data, financial records, or intellectual property. Data breaches can have devastating consequences, such as identity theft, fraud, reputational damage, legal liability, and loss of trust.




In this blog post, we will look at the top 5 IT data breaches in the past 5 years according to the number of people affected, based on the information from StatistaUpGuardCNBCCSO Online, and Tech.co. We will also discuss the similarities of these breaches, how they could have been prevented, and what damage was done.


1. Yahoo

Number of people affected: Over 3 billion

Years: 2013-2016


Yahoo is one of the largest and most popular web services providers in the world, offering email, news, search, and social media platforms. However, between 2013 and 2016, Yahoo suffered multiple data breaches that compromised the records of all its user accounts, which included names, email addresses, phone numbers, birth dates, passwords, calendars, and security questions. The breaches were carried out by a team of Russian hackers who used backdoors, stolen backups, and access cookies to gain access to Yahoo’s database. Yahoo was slow to react and disclose the incidents, which resulted in a $35 million fine and 41 class-action lawsuits.


Similarities: The Yahoo breaches were similar to other data breaches in terms of the type of data stolen, the methods used by the hackers, and the lack of timely response and notification by the company.


Prevention: The Yahoo breaches could have been prevented by implementing stronger security measures, such as encryption, multi-factor authentication, regular backups, and vulnerability scanning. Yahoo could have also notified its users and authorities sooner and urged them to change their passwords and security questions.


Damage: The Yahoo breaches caused significant damage to the company’s reputation, trust, and value. Yahoo lost millions of users and potential customers, as well as billions of dollars in market capitalization and acquisition deals. The breaches also exposed the users to the risk of identity theft, phishing, and spam.


2. Microsoft

Number of people affected: 30,000 US companies (60,000 companies worldwide)

Year: 2021


Microsoft is one of the leading technology companies in the world, providing software, hardware, cloud, and gaming products and services. In 2021, Microsoft was hit by a massive cyberattack that targeted its Exchange email servers, one of the largest email servers in the world. The hackers exploited four different zero-day vulnerabilities that allowed them to gain unauthorized access to emails from small businesses to local governments. The hackers were able to access the servers for three months before Microsoft detected and patched the flaws.


Similarities: The Microsoft breach was similar to other data breaches in terms of the scale, duration, and sophistication of the attack, as well as the type of data exposed.


Prevention: The Microsoft breach could have been prevented by applying more rigorous testing and monitoring of its software, as well as by informing and assisting its customers to update and secure their systems.


Damage: The Microsoft breach caused severe damage to the company’s credibility, reliability, and security. Microsoft faced criticism and lawsuits from its customers, partners, and regulators, as well as potential loss of revenue and market share. The breach also exposed the customers to the risk of espionage, sabotage, and ransomware.


3. Facebook

Number of people affected: Over 2.7 billion

Years: 2018-2021


Facebook is one of the most popular and influential social media platforms in the world, connecting billions of people and businesses. However, between 2018 and 2021, Facebook experienced several data breaches that exposed the records of over 2.7 billion users, which included names, phone numbers, email addresses, locations, birthdays, genders, and interests. The breaches were caused by various factors, such as third-party apps, scraping tools, and configuration errors. Facebook was accused of failing to protect its users’ data and privacy, as well as of violating several laws and regulations.


Similarities: The Facebook breaches were similar to other data breaches in terms of the type and volume of data leaked, the sources and motives of the attackers, and the legal and ethical implications of the incidents.


Prevention: The Facebook breaches could have been prevented by implementing stricter data protection policies, practices, and controls, such as limiting data access and sharing, enforcing data retention and deletion, and auditing and reviewing data security. Facebook could have also notified its users and authorities promptly and transparently, and offered them tools and options to safeguard their data and privacy.


Damage: The Facebook breaches caused immense damage to the company’s reputation, trust, and compliance. Facebook faced backlash and boycotts from its users and advertisers, as well as fines and investigations from various governments and agencies. The breaches also exposed the users to the risk of identity theft, fraud, and manipulation.


4. Marriott

Number of people affected: Over 500 million

Years: 2014-2018


Marriott is one of the largest and most renowned hotel chains in the world, operating thousands of properties across the globe. However, between 2014 and 2018, Marriott suffered a data breach that affected the records of over 500 million guests who stayed at its Starwood-branded hotels, which included names, addresses, phone numbers, email addresses, passport numbers, dates of birth, and travel details. The breach was attributed to a Chinese state-sponsored hacking group that infiltrated the Starwood reservation system and remained undetected for four years. Marriott discovered the breach in 2018, after it acquired Starwood in 2016.


Similarities: The Marriott breach was similar to other data breaches in terms of the type and amount of data compromised, the actors and objectives of the attack, and the delay and difficulty in detecting and disclosing the breach.


Prevention: The Marriott breach could have been prevented by conducting more thorough due diligence and integration of its acquired businesses, as well as by applying more robust security measures, such as encryption, segmentation, and monitoring of its systems and data. Marriott could have also notified its guests and authorities sooner and offered them compensation and protection.


Damage: The Marriott breach caused enormous damage to the company’s reputation, loyalty, and profitability. Marriott faced lawsuits and complaints from its guests and partners, as well as penalties and sanctions from various countries and regulators. The breach also exposed the guests to the risk of identity theft, fraud, and espionage.


5. Equifax

Number of people affected: Over 147 million

Year: 2017


Equifax is one of the largest and most influential credit reporting agencies in the world, collecting and analyzing the financial and personal data of millions of consumers and businesses. However, in 2017, Equifax suffered a data breach that exposed the records of over 147 million people, which included names, social security numbers, birth dates, addresses, and driver’s license numbers. The breach was caused by a known vulnerability in a web application that Equifax failed to patch and secure. The hackers exploited the flaw and accessed the data for over two months before Equifax discovered and reported the breach.


Similarities: The Equifax breach was similar to other data breaches in terms of the type and value of data stolen, the cause and impact of the breach, and the response and accountability of the company.


Prevention: The Equifax breach could have been prevented by updating and patching its software, as well as by implementing stronger security measures, such as encryption, authentication, and logging of its data and systems. Equifax could have also notified its customers and authorities faster and more accurately, and provided them with adequate support and remedies.


Damage: The Equifax breach caused tremendous damage to the company’s reputation, trust, and responsibility. Equifax faced outrage and criticism from its customers and stakeholders, as well as lawsuits and investigations from various states and agencies. The breach also exposed the customers to the risk of identity theft, fraud, and litigation.


I hope you found this blog post helpful and informative. If you have any questions or feedback, please feel free to leave a comment below.

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