Top 5 Greatest Computer Hacks In History

Hacking is about manipulating and bypassing systems to force them to do the unintended.

While most hackers are benign hobbyists, some hackers do inflict terrible widespread damage and cause financial and emotional hurt. Victimized companies lose millions in repair and restitution costs; victimized individuals lose their jobs, their bank accounts, and even their relationships.

So what are examples of large-scale hacks that wreaked this much havoc? What are the greatest hacks of recent history?

With 'greatest' being synonymous with 'harshest', here is a list of noteworthy hacks from the last 20 years. As you read this list below, you will certainly want to reconsider your own password practices. We've enclosed some strong suggestions at the bottom of this article to help you reduce the risk that you too will be hacked one day.

01

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Ashley Madison Hack 2015: 37 Million Users

The hacker group Impact Team broke into the Avid Life Media servers and copied the personal data of 37 million Ashley Madison users. The hackers then incrementally released this information to the world through various websites. The shameful impact on people's personal reputations has had ripples across the world, including claims that user suicides followed after the hack.

This hack is memorable not only because of the sheer publicity of the impact, but because the hackers also earned some fame as vigilantes crusading against infidelity and lies.  

02

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The Conficker Worm 2008: Still Infecting a Million Computers a Year

While this resilient malware program has not wreaked irrecoverable damage, this program refuses to die; it actively hides and then nefariously copies itself to other machines. Even more frightening: this worm continues to open backdoors for future hacker takeovers of the infected machines.

The Conficker worm program (aka 'Downadup' worm) replicates itself across computers, where it lies in secret to either a) convert your machine into a zombie bot for spamming, or b) to read your credit card numbers and your passwords through keylogging, and transmit those details to the programmers.  

Conficker/Downadup is a very smart computer program. It defensively deactivates your antivirus software in order to protect itself.

Conficker is noteworthy because of its resilience and reach; it still travels around the Internet 8 years after its discovery.

03

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Stuxnet Worm 2010: Iran's Nuclear Program Blocked

A worm program that was less than a megabyte in size was released into Iran's nuclear refinement plants. Once there, it secretly took over the Siemens SCADA control systems. This sneaky worm commanded over 5000 of the 8800 uranium centrifuges to spin out of control, then suddenly stop and then resume, while simultaneously reporting that all is well. This chaotic manipulating went on for 17 months, ruining thousands of uranium samples in secret, and causing the staff and scientists to doubt their own work. All the while, no one knew that they were being deceived and simultaneously vandalized. This devious and silent attack wreaked far more damage than simply destroying the refining centrifuges themselves; the worm led thousands of specialists down the wrong path for a year and a half and wasted thousands of hours of work and millions of dollars in uranium resources. The worm was named 'Stuxnet', a keyword that was found in the code's internal comments. This hack is memorable because of both optics and deceit: it attacked a nuclear program of a country that has been in conflict with the USA and other world powers; it also deceived the entire nuclear staff for a year and a half as it performed its nasty deeds in secret.

04

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Home Depot Hack 2014: Over 50 Million Credit Cards

By exploiting a password from one of its stores' vendors, the hackers of Home Depotachieved the largest retail credit card breach in human history. Through careful tinkering of the Microsoft operating system, these hackers managed to penetrate the servers before Microsoft could patch the vulnerability.

Once they entered the first Home Depot store near Miami, the hackers worked their way throughout the continent. They secretly observed the payment transactions on over 7000 of the Home Depot self-serve checkout registers. They skimmed credit card numbers as customers paid for their Home Depot purchases.

This hack is noteworthy because it was against a monolithic corporation and millions of trusting customers.

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eBay Hack 2014: 145 Million Users Breached

 eBay: the world's la

Some people say this is the worst breach of public trust in online retail. Other say that it was not nearly as harsh as mass theft because only personal data was breached, not financial information.

Whichever way you choose to measure this unpleasant incident, millions of online shoppers have had their password-protected data compromised. This hack is particularly memorable because it was very public, and because eBay was painted as weak on security because of their slow and lackluster public response.