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White hackers are known as good peoples, these peoples do not violate any rule or regulations but these peoples do work under the limits of law.These peoples enter in to the system according to limits and tell the peoples about their system security holes or remove that security holes from the system or server.
The purpose of these activities of White hat hackers are just for the security improvement, majority of these peoples are employee of computer security companies, these are also called sneakers and their team or group is called tiger team.
The main difference between white hat hackers and black hat hackers is that white hat hackers always try to make the security system better and better while black hat hackers always try to break the security for their bad purposes but black hat hackers always try to make their own system security better.
Microsoft Windows Operating System sales with cryptography libraries but when this operating system is sale outside the america then these cryptography libraries becomes useless because operating system can not load these libraries.This system only runs those libraries which are signed by Microsoft , Microsoft is bounded that it has to take permission from American Government before signing any library to the outside of america, due to this america has limited these cryptography libraries in just america.
But the hackers from outside america has find out a way to load these libraries in their operating which are not signed by america. Although this activity looks like bad but many hacking communities called it white hacking because in this way cryptography will spread in to the whole world.
Today's world search engines are also performing white hat and black hat activities, in search engine black hat activity is called spamdexing because when somebody search for any thing in search engine the result will be redirect to specific website.
(3) Gray Hat Hackers
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Gray hat hackers are known as expert hackers in computer community who work some time legally (according to law) and some time do work illegally ( violate the law). Majority of gray hat hackers do not want to harm any system or server but some time the can do any illegal work during their work.
Gray hat hackers is the intermediate type of hackers which lies between the black hat hackers and white hat hackers. Majority of gray hat hackers when enters in to the system they do not harm the system but just leave their names in the system.
Apache Hacked By Gray Hat Hackers in 2004
In 2004 some gray hat hackers hacked the apache.org server but the did not harm the server,they did not leave any virus, the did not warn Apache employees but hey just inform Apache peoples to their security holes.