Top 5 Most Dangerous Cyber Attacks of All Time [Full Story]

The threat of cyberattacks has increased over time, affecting not only government institutions but also small enterprises and respective individuals. The problematic thing is that cybercriminals’ techniques are evolving along with technology, making it increasingly difficult for even the most sophisticated security measures to keep pace and protect your sensitive data from being stolen.

In this blog post, we will explore the backstories, the impact, and the lessons learned of the top five most notorious cyber threats in history. The latest data breaches record revealed approximately 1 billion personal records and ransomware have surpassed in 2025 and are rising.

In this post, travel with us to the not-so-distant past to look at how some of the biggest security incidents of all time went down. So, without further ado, let’s roll back.

Before proceeding, you should consider reading this: Understanding Cyberattack- Top Useful Cyber Security Hacks

Let’s Look Back At The Most Notorious Cyber Threats of All Time

The following section covers the biggest cyberattacks in history and their lasting impact.

1. The Target Data Breach (2013)

Date: 19^th December 2013

Impact:

• Compromised Data: About 40 million credit and debit card numbers were taken, and an additional 70 million customers’ names, addresses, and phone numbers were also taken.
• Identity Theft Risks: Millions of consumers now face a far higher risk of identity theft as a result of the disclosure of private data.

The Attack’s Story:

Target’s systems were breached by hackers using credentials from a third-party provider. During the busy holiday shopping season, they gained access to point-of-sale (POS) machines and stole millions of credit and debit card numbers.

Target suffered approximately $200 million in damages as well as a damaged reputation as a result of the hack, which exposed the risks associated with subpar vendor security procedures.

2. The Mirai Botnet Attack (2016)

Date: 21^st October, 2016

Impact:

• Internet services were disrupted nationwide.
• Impacted well-known websites like Reddit, Spotify, Twitter, and Amazon.
• Millions of users in the US and Europe experienced service interruptions as a result of this attack.
• Vulnerabilities in Internet of Things (IoT) devices that have been made public.

The Attack’s Story:

Mirai was created to infect susceptible Internet of Things (IoT) devices, including digital video recorders (DVRs), routers, and IP cameras. The botnet found these devices easily since they frequently had weak default passwords. Once infected, these gadgets became “bots,” which the attackers could operate remotely.

The size of the botnet was its greatest asset. Attackers could initiate enormous DDoS attacks by seizing hundreds of thousands of compromised devices, flooding targeted servers and networks with traffic.

3. WannaCry Ransomware (2017)

Date: 12^th May 2017

Impact:

• Over 200,000 computers are among the impacted systems.
• Financial Cost: Damages were estimated to be over $4 billion.
• Consequences: Significant disruptions in several industries, notably the NHS in the United Kingdom.

The Attack’s Story:

A flaw in Microsoft Windows was used by the worldwide ransomware assault WannaCry to encrypt data on compromised PCs. In order to decode the file, the attackers wanted payment in Bitcoin. Systems in hospitals, banks, and enterprises closed up, paralyzing them.

The EternalBlue exploit, purportedly created by the NSA and released by a hacker collective, was blamed for the attack’s quick spread. Despite attempts to lessen its impact, WannaCry sparked worldwide unrest and brought attention to the weaknesses in unpatched systems.

4. NotPetya (2017)

Data: June, 2017

Impact:

• Global Reach: NotPetya impacted over 2,300 organizations across more than 60 countries.
• Resulted in damages exceeding $10 billion. It affected companies all across the world, with Ukrainian organizations being particularly affected.
• Hampered the operations of large corporations like FedEx, Merck, and Maersk.

The Attack’s Story:

Initially posing as ransomware, NotPetya was a destructive wiper malware that caused significant harm all around the world. The assault started with a hacked Ukrainian tax program and quickly expanded across networks using the same EternalBlue flaw that WannaCry took advantage of.

Unlike other ransomware, NotPetya’s main objective was to inflict as much disruption as possible rather than make money. Even if the ransom was paid, the victim’s data would be permanently encrypted once infected, making recovery impossible. The attack highlighted the dangers of supply chain vulnerabilities by destroying Ukraine’s government, banking, and transportation infrastructure and reaching out to multinational firms.

5. SolarWinds Supply Chain Attack (2020)

Date: March 2020 (discovered in December 2020)

Impact:

• Impacted more than 18,000 SolarWinds clients, including telecom businesses, technology enterprises, and government organizations.
• Major private companies like Microsoft, Intel, Cisco, and FireEye. This led to serious data breaches and espionage operations.

The Attack’s Story:

The incident started in September 2019 when threat actors—later identified as APT29 or Nobelium, a Russian espionage group—infiltrated SolarWinds’ network. The attackers introduced malicious code, or a backdoor, into Orion software updates in February 2020. Customers were unaware that this malicious update had been sent to them. Cybersecurity company FireEye initially identified the issue in November 2020 after learning that the malicious updates had affected its systems.

Consider reading our previous article: Guide on Internet Security: How To Protect Yourself Online.

KEY TAKEAWAY:

Well, stronger cybersecurity measures are certainly required as a result of these intrusions, which have revealed weaknesses in our digital infrastructure. Prioritizing security, making significant defence investments, and keeping abreast of emerging threats are all imperative for organizations. People should also take precautions to safeguard their data and adopt safe cybersecurity practices.

Cybercriminals’ strategies will change in tandem with technology. Organizations and individuals need to take a proactive approach to cybersecurity in order to keep ahead of these threats.

PEOPLE ALSO ASK:

Q1. Describe ransomware in brief.  

A1: A form of virus known as ransomware encrypts data on a victim’s computer or network unless the decryption keys are purchased.

Q2: How can businesses guard against cyberattacks?

A2: Companies should invest in cutting-edge threat detection technologies, train staff on cybersecurity awareness, carry out frequent audits, and put in place robust security procedures.

Q3: How can people defend themselves against online dangers?

A3: People should update software frequently, create strong passwords, activate two-factor authentication, and exercise caution when disclosing personal information online.