Biggest Cyberattacks have become a major global security threat, impacting individuals, corporations, and governments. Some of the most notorious cyber incidents in history are known for their scale, complexity, and lasting impact. Notable among them is the 2000 “Mafiaboy” attack, where a 15-year-old hacker executed a massive distributed denial-of-service (DDoS) attack on high-profile websites like CNN, Dell, and eBay, disrupting online services.
Another significant event was the 2007 cyberattack on Estonia, which crippled critical infrastructure, affecting government websites, financial systems, and media outlets. In 2014, the Sony Pictures hack, blamed on North Korean operatives, leaked sensitive data and wreaked havoc on the entertainment sector.
These incidents showcase the rising sophistication of cyber threats and the profound impact on both private and public sectors. As a result, cybersecurity has emerged as a crucial priority in today’s digital landscape.
Most Notorious Cyber Attacks in History
Cyberattacks come in various forms, including malware, phishing, Denial-of-Service (DoS) attacks, Distributed Denial-of-Service (DDoS) attacks, and SQL injection.
These attacks can target a wide range of entities, such as government agencies, corporations, educational institutions, and individuals.
Read More: PM kisan 19th Installment Date 2025: PM किसान 19वीं क़िस्त कब आएगा, तिथि हुआ जारी
The Melissa Virus (1999)
The Melissa Virus, one of the first major cyberattacks, highlighted the urgent need for digital security. In 1999, programmer David Lee Smith used an AOL account to send an email attachment claiming to provide access to adult website passwords. Instead, the file unleashed a virus when downloaded. The attack caused significant damage, affecting both users and companies, including Microsoft. Although cybersecurity measures quickly contained the virus, its full eradication took time. The total financial impact of the attack was estimated at $80 million.
NASA Cyber Attack (1999)
In 1999, NASA experienced a major cybersecurity breach, resulting in unauthorized access and the shutdown of its computer systems for 21 days. During the attack, approximately 1.7 million software files were downloaded, leading to repair costs of around $41,000. What made this breach particularly notable was the identity of the attacker—a 15-year-old hacker who later confessed. He was sentenced to six months in jail and required to write apology letters to NASA administrators and the Secretary of Defense.
Estonia Cyber Attack (2007)
In 2007, Estonia became the first nation to experience a full-scale cyberattack. The Distributed Denial of Service (DDoS) attack targeted 58 Estonian websites, including government, media, and banking sites. It overwhelmed servers using zombie computers to amplify the attack’s impact. Linked to a political dispute over a statue’s relocation in the capital, the incident caused an estimated $1 million in damages.
Heartland Payment Systems (2009)
In early 2009, Heartland Payment Systems disclosed a 2008 breach that exposed credit card data, leading Visa to temporarily remove the company from its systems. Heartland was required to prove compliance with PCI DSS standards before reinstatement. In response, the company implemented encryption across its entire account information system, establishing a new security benchmark for the card processing industry.
China’s Google Attacks (2009)
In 2009, a series of espionage attacks targeted Chinese humanitarian activists. Hackers accessed their Google accounts to monitor communications, with malfunctions alerting users to the breach. Investigations revealed the hackers tracked individuals across multiple countries, likely through phishing and malware. This incident underscores the need to identify and report suspicious activity on online platforms promptly.
Sony’s PlayStation Network Hack (2011)
The 2011 PlayStation Network hack is one of the largest data breaches in history, affecting over 77 million accounts and causing a nearly month-long shutdown. Sony took 23 days to restore the network, resulting in an estimated loss of $171 million. While the hackers were never identified, Sony compensated affected users with a free month of premium service and introduced a $1 million identity theft insurance policy.
Target Security Breach (2013)
In December 2013, Target experienced one of the largest data breaches in history, with cybercriminals stealing over 40 million credit and debit card details and 70 million customer records. The breach was traced to a third-party vendor with remote access to Target’s network. In response, Target shut down its point-of-sale systems on December 19 and 20 and offered free credit monitoring and theft protection. In 2017, Target reached an $18.5 million settlement with several states over the breach.
Adobe Cyber Attack (2013)
In October 2013, Adobe revealed a breach in which hackers accessed nearly 3 million encrypted customer credit card records and login details. Further investigation showed the breach also involved 150 million encrypted usernames, hashed passwords, customer names, and payment card information. In August 2015, Adobe settled allegations of violating the Customer Records Act and engaging in unfair business practices.
Cyber Attack on Yahoo (2013-2014)
The 2014 Yahoo breach, one of the largest cyberattacks in history, impacted all 3 billion user accounts. However, Yahoo did not disclose the breach until 2016. The attack, carried out by a Russian hacker group, began with a spear-phishing email sent to a Yahoo employee. A single click granted the hackers access to Yahoo’s network, exposing sensitive data including usernames, email addresses, security questions, and phone numbers.
Snapchat Users’ Personal Information Leaked (2015)
In 2015, Snapchat faced a major breach that exposed the app’s failure to maintain user anonymity. Hackers revealed the usernames, phone numbers, and locations of 4.6 million accounts, alarming users, especially those sharing sensitive content. Although the hackers had warned Snapchat about the vulnerability, the company failed to respond. While no financial losses occurred, Snapchat took over a year to recover from the incident’s aftermath.
Ukraine’s Power Grid Attack (2015)
In December 2015, Ukraine’s power grid was targeted in a cyberattack that left over 200,000 people without electricity for hours. Attributed to the Russian-linked hacker group Sandworm, the attack used BlackEnergy malware along with the KillDisk and VPNFilter attack frameworks, severely disrupting the nation’s critical infrastructure.
WannaCry Ransomware Attack (2017)
In May 2017, the WannaCry ransomware exploited a Microsoft Windows vulnerability, EternalBlue, to spread quickly across global networks. Once infected, WannaCry encrypted computers, demanding ransoms starting at $300 and rising over time. The attack impacted over 230,000 computers in 150 countries, with major victims including the UK’s National Health Service (NHS), FedEx, Nissan, and Honda. Microsoft was unaware of the vulnerability, and no patch had been released before the attack.
Equifax Data Breach (2017)
In 2017, Equifax, a leading U.S. credit reporting agency, suffered a massive data breach that compromised the personal information of over 147 million Americans—more than 40% of the population. The breach, occurring between May and July 2017, exposed sensitive data including names, addresses, dates of birth, Social Security numbers, driver’s license numbers, and 200,000 credit card numbers. The breach was traced to a vulnerability in Equifax’s web application firewall, which allowed cybercriminals unauthorized access to its systems. As a result, Equifax faced a $575 million fine from the Federal Trade Commission, the Consumer Financial Protection Bureau, and 50 U.S. states and territories.
NotPetya Ransomware Attack (2017)
In 2017, the NotPetya ransomware attack affected over 12,500 computers worldwide, primarily targeting Microsoft Windows systems. Unlike typical ransomware, NotPetya encrypted data while also rendering computers completely inoperable. The attack caused severe damage to major global companies, including FedEx, Maersk, Russian oil giant Rosneft, and British advertising firm WPP. FedEx reported losses of $300 million, and one of its subsidiaries had to halt operations.
Cyber Attack on Marriott Hotels (2018)
In September 2018, Marriott International revealed a cyberattack that exposed sensitive information of around 500 million Starwood Preferred Guests. The breached data included names, email addresses, phone numbers, passport details, account information, dates of birth, gender, reservation dates, and more. As a result, Marriott was fined £18.4 million by the UK ICO in 2020 for failing to adequately protect customer data.
Frequently Asked Questions
What is the biggest cyberattack in history?
The Yahoo 2013 breach, affecting all 3 billion accounts, is considered one of the largest cyberattacks in history.
How did the 2014 Sony PlayStation Network breach happen?
The 2014 PlayStation Network breach occurred due to a cyberattack by a hacker group, which led to a 23-day network shutdown and financial losses of approximately $171 million.
What was the impact of the 2017 WannaCry ransomware attack?
The WannaCry attack affected over 230,000 computers across 150 countries, including major companies like FedEx and the UK’s NHS. It exploited the EternalBlue vulnerability in Microsoft Windows.
Who was behind the 2017 Equifax breach?
Hackers exploited a vulnerability in Equifax’s web application firewall, exposing the personal data of over 147 million people, resulting in a $575 million fine for the company.
What was the outcome of the 2013 Target data breach?
The Target breach, impacting 40 million credit card details, led to financial losses of $171 million and a year-long recovery period.
How did the NotPetya ransomware attack differ from other cyberattacks?
Unlike typical ransomware, NotPetya not only encrypted data for ransom but also rendered infected computers completely inoperable, affecting major companies worldwide.
What caused the 2015 Adobe data breach?
Hackers gained access to Adobe’s systems, exposing sensitive data such as credit card information and personal account details for millions of users.
How did hackers target Ukraine’s power grid in 2015?
In December 2015, a cyberattack on Ukraine’s power grid left over 200,000 people without electricity, attributed to Russian-linked hackers using malware like BlackEnergy.
Conclusion
The 15 biggest cyberattacks in history serve as a stark reminder of the vulnerabilities present in our digital infrastructure. From the massive breaches at Yahoo and Equifax to the disruptive ransomware attacks like WannaCry and NotPetya, these incidents have impacted millions of people and caused severe financial losses for companies. The common thread in many of these attacks is the exploitation of security weaknesses, whether through phishing, software vulnerabilities, or inadequate data protection measures.
These breaches highlight the critical importance of robust cybersecurity practices, proactive threat detection, and timely responses to emerging threats. As technology continues to evolve, organizations and individuals alike must remain vigilant to safeguard sensitive data and ensure the security of digital systems worldwide.