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The Top 10 Notorious Hacks of all time: Lessons from the Biggest Cyber Incidents

October 10, 2023
Edward Chopskie

The digital era has brought unparalleled conveniences and innovations, but it has also opened doors for cybercriminals to exploit vulnerabilities and utilize other attack vectors. The world has witnessed numerous security breaches, with some incidents leading to massive data losses, financial damages, and severely dented reputations for corporations. From giants like Equifax to household names like Yahoo, no organization is immune. 

With an increasingly interconnected world, the doors for cybercriminals have swung wide open. These malicious actors are not just individuals looking for a quick score but are often sophisticated networks or state-sponsored entities with resources, time, and motivation. They are in constant search for vulnerabilities, hoping to exploit these gaps to gain unauthorized access, disrupt services, or steal sensitive information.

As technology continues to evolve and integrate deeply into our daily lives, it’s crucial for us and all organizations to remember the recent significant incidents and the lessons they have taught us. With all that said, let’s delve into the top 10 most notorious security breaches in history (in no particular order). 

1. Equifax (2017)

Breach Details: This colossal breach unveiled the personal details of an astonishing 147 million individuals. Intruders exploited a known, yet neglected vulnerability.  Names, Social Security numbers, birth dates, and addresses were among the stolen data. An unpatched system was the initial entry point that facilitated an injection attack. 

Fines: Equifax Inc. has agreed to pay at least $575 million, and potentially up to $700 million, as part of a global settlement

Lesson: Organizations must update software patches regularly and prioritize data encryption.

2. Yahoo (2013-2014)

Breach Details: Yahoo faced two major breaches. The one in 2013 affected all 3 billion user accounts, while the one in 2014 impacted 500 million.The attackers utilized an SQL injection attack to gain initial access. 

Fines: Settlement Fund of $117M 

Lesson: Continuous monitoring and timely disclosure are crucial. Companies should be transparent about breaches to maintain trust. This incident became a case study, accentuating the merits of continuous vigilance and the ethos of transparent disclosure.

3. Marriott International (2018)

Breach Details: A staggering amount of personal data from approximately 500 million guests was exposed over four years due to unauthorized access to the reservation database. The attack exploited poorly implemented or misconfigured access controls. This incident became a case study, accentuating the merits of continuous vigilance and the ethos of transparent disclosure.

Fines: Litigation ongoing 

Lesson: Regular security audits can help in early detection of vulnerabilities and unauthorized access.

4. Target (2013)

Breach Details: A breach of epic proportions, the credit and debit card information of 40 million customers and personal details of 70 million customers were compromised. Stolen credentials from a Target business partner led to malware being installed on Target’s POS terminals. 

Fines: ~$20M 

Lesson: Point-of-sale systems are attractive targets. Enhanced network segmentation and card encryption are critical.

5. Capital One (2019)

Breach Details: A former AWS employee exploited an SSRF vulnerability, compromising data of over 100 million individuals.

Fines: Capital One will pay $190,000,000 into a Settlement Fund.

Lesson: Cloud configurations must be properly secured, and companies should be wary of insider threats.

6. Adult Friend Finder (2016)

Breach Details: More than 412 million user accounts from the FriendFinder Networks were exposed. There is speculation about whether a Local File Inclusion (LFI) vulnerability was used to gain access. 

Fines: None 

Lesson: Password encryption is non-negotiable. Using robust encryption methods can protect user data even if there’s a breach.

7. Heartland Payment Systems (2008)

Breach Details: Data from 134 million credit cards were exposed due to SQL injection leading to installation of  malware on the company’s network. 

Fines: $60M

Lesson: Companies must regularly update and patch software vulnerabilities. A robust intrusion detection system can provide early warnings.

8. Anthem (2015)

Breach Details: Personal information of 78.8 million current and former customers and employees was exposed. The attack on Anthem started with a successful spear-phishing campaign.

Fines: $40M 

Lesson: Multi-factor authentication and training employees to recognize phishing attempts can prevent unauthorized access.

9. Sony’s PlayStation Network (2011)

Breach Details: 77 million PlayStation Network accounts were compromised, leading to a 23-day system outage. Reports suggest that the attackers gained access to Sony’s system using a known vulnerability.

Fines: $15M settlement 

Lesson: Rapid incident response can minimize damage. Keeping users informed can help in damage control.

10. Home Depot (2014)

Breach Details: Over 50 million credit card details were exposed due to a malware attack.

Fines: $17.5 million-dollar settlement

Lesson: Regularly updating security solutions and closely monitoring network activity can prevent malware breaches.


In our digital age, while we enjoy unmatched conveniences and technological advances, we also confront a growing threat from cybercriminals seeking to exploit system vulnerabilities and other attack avenues. These notable breaches underscore the ever-present and evolving dangers in the digital shadows. It’s imperative for organizations to elevate cybersecurity, continuously refine their protective measures, invest in employee training, and maintain a proactive defense stance. There’s wisdom in the adage: those who forget the past are condemned to relive it. Nowhere is this more pertinent than in cybersecurity.

Past breaches should not just be seen as unfortunate incidents but as lessons. By understanding how these breaches occurred, organizations can take steps to ensure they don’t fall victim to similar threats.

To summarize, the digital age is indeed a time of unparalleled progress and convenience. But with great power comes great responsibility. Organizations must recognize the growing cyber threats and take the necessary steps to safeguard their assets, reputation, and, most importantly, their customers. In the realm of cybersecurity, staying informed, vigilant, and proactive is not just a recommendation—it’s a mandate.

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