The 1970s was a timeframe in information security history largely untouched by digital calamity, but marked more so by the exploration of emerging telecommunications technology. The first modern day hackers appeared as they attempted to circumvent the system and make free phone calls, a practice that became known as "phreaking." Perhaps the most publicly well know phreaker was John Draper, a.k.a. Captain Crunch, who helped pioneer the practice. Draper was later arrested and convicted on charges related to his nefarious phreaking activities multiple times.
1980s
The 1980s saw the birth of computer clubs. This decade subsequently ushered in the era of malware, marking the first virus, named "Brain", in 1986 as well as the infamous Morris Worm in 1988., The Computer Fraud and Abuse Act was instituted in 1986 and for the first time, a computer hacker, Kevin Poulsen, was featured on America's Most Wanted. Poulsen was finally arrested in 1991, after spending several years as a fugitive. Since his release from prison, however, he has reinvented himself as a journalist and at one point, regularly wrote for the online computer security news portal SecurityFocus, which was purchased by Symantec in 2002.
1990s
The 1990's brought with it the dawn of the modern information security industry. Notable threats witnessed during this decade included the Michelangelo virus, Melissa, and Concept. Distributed denial of service attacks and the bots that made them possible were also born, such as Trin00, Tribal Flood network and Stacheldracht.
Beyond malware, AOL suffered through the first real phishing attacks as fraudsters aimed their efforts at stealing users' credentials. Privacy watchdogs called out in concern as tracking cookies were born, allowing ad networks to monitor user surfing behaviors in a rudimentary fashion.
2000s
The first decade of the 21st Century saw malicious Internet activity turn into a major criminal enterprise aimed at monetary gain. Adware and spyware entered the scene with such programs as Conducent TimeSink, Aureate/Radiate and Comet Cursor.
Perhaps even more visible than adware and spyware, aggressively self-propagating malware also appeared. Big name threats such as Code Red, Nimda, Welchia, Slammer and Conficker all began taking advantage of unpatched machines. Phishing attacks also became mainstream; first heavily targeting online banking then moving onto social networking sites. Zero day attacks, rootkits, rogue antispyware, SPIM, clickfraud and other attacks also all made their mainstream debut in the current decade.
Source: Symantec