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An Internet leak occurs when a party's confidential information is released to the public on the Internet. Various types of information and data can be, and have been, "leaked" to the Internet, the most common being personal information, computer software and source code, and artistic works such as books or albums. For example, a musical album is leaked if it has been made available to the public on the Internet before its official release date; this musical material is still intended to be confidential.
Source Code Leaks 
Source code leaks are usually caused by misconfiguration of software like CVS or FTP which allow people to get source files by exploiting this, by software bugs, or by employees that have access to the sources of part of them revealing the code in order to harm the company.
There were many cases of source code leaks in the history of software development. For example, in 2003 a hacker exploited a security hole in Microsoft's Outlook to get the complete source of Half-Life 2, which was under development at the time. The complete source was soon available in various file sharing networks. This leak was rumored to be the cause of the game's delay, but later was stated not to be.
Also in 2003, source code to Diebold Election Systems Inc. voting machines was leaked. Researchers at Johns Hopkins University and Rice University published a damning critique of Diebold's products, based on an analysis of the software. They found, for example, that it would be easy to program a counterfeit voting card to work with the machines and then use it to cast multiple votes inside the voting booth.
Another case involved a partial leak of the source code to Microsoft Windows 2000. Two files containing Microsoft source code were circulating on the Internet. One contains a majority of the NT4 source code and the other contains a fraction of the Windows 2000 source code, reportedly about 15% of the total. This includes some networking code including Winsock and inet; as well as some shell code. It was feared that because of the leak, the number of security exploits would increase due to wider scrutiny of the source code.
In 2004 partial (800MB) proprietary source code that drives Cisco Systems' networking hardware was made available in the internet. The site posted two files of source code written in the C programming language, which apparently enables some next-generation IPv6 functionality. News of the latest source code leak appeared on a Russian security site.
In January 2011 the "stolen source code" of Kaspersky Anti-Virus 2008 was published on the Pirate Bay.
In December 2011, the source code of the Oracle Solaris 11 was available via BitTorrent.
In January 2012, it was confirmed that Anonymous hackers stole source code (about 1 GiB) for Symantec's pcAnywhere from the company's network in 2006. How the hackers accessed the network is still unclear.
Other Leaks 
On January 28, 2008, Nintendo's crossover fighting video game Super Smash Bros. Brawl for the Wii console had a major leak having to do with unconfirmed playable characters. The leak was unintentionally started by the Japanese language www.wii.com website, which released a video that included small images of not-yet confirmed characters within the game. The website fixed this mistake, but the leak still continued. Websites like YouTube contain screenshots and video gameplay of the unconfirmed characters of the game.
Sometimes, game developers who post blogs can accidentally leak information.
Recently, several high-profile books have been leaked on the Internet before their official release date, including If I Did It, Harry Potter and the Deathly Hallows, and an early draft of the first twelve chapters of Midnight Sun. The leak of the latter prompted the author Stephenie Meyer to suspend work on the novel.
High-profile Internet leaks 
- 3 October 2003: Half-Life 2 source code
- 13 February 2004: Microsoft Windows 2000/NT source code
- November 2009: Climatic Research Unit email leak, aka Climategate
See also 
- "Playable Version of Half-Life 2 Stolen". CNN Money. 2003-10-07. Retrieved February 14, 2007.
- "Half Life 2 Source-Code Leak Delays Debut". TechNewsWorld. Retrieved February 14, 2007.