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, 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 instance, as Fraunhofer IIS released in 1994 only a low quality version of their MP3 encoding software (l3enc), a hacker named SoloH gathered the source code from the unprotected servers of the University of Erlangen and developed a higher quality version, which started the MP3 revolution on the internet.
Around 1996 Electronic Arts accidentally put the source code of FIFA 97 on a demo disc.
In 2003 a hacker exploited a security hole in Microsoft's Outlook to get the complete source of the video game 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.
In 2003 a Chinese Hacker acquired the Lineage II source code, and sold it to someone who set up alternative servers. Shutdown by FBI in 2007.
In 2003, one year after 3dfx was bought by Nvidia and support ended, the source code for their drivers leaked, resulting in fan-made, updated drivers.
In 2004, a large portion of Windows NT 4.0's source code and a small percentage (reportedly about 15%) of Windows 2000's were leaked online. The Windows 2000 source code leak was analysed by a writer for (now defunct) website Kuro5hin who noted that while the code was generally well written, allegedly "there are a dozen or so 'fucks' and 'shits', and hundreds of 'craps'." The writer also noted that there were a lot of code hacks, with the "uglier" ones mostly being for compatibility with older programs and some hardware. It was feared that because of the leak, the number of security exploits would increase due to wider scrutiny of the source code. It was later discovered that the source of the leak originated from Mainsoft.
Also in 2004, partial (800 MB) 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 2006, Anonymous hackers stole source code (about 1 GiB) for Symantec's pcAnywhere from the company's network. While confirmed in January 2012, it is still unclear how the hackers accessed the network.
In late 2007, the source code of Norton Ghost 12 and a
Norton Anti-Spyware version were available via BitTorrent.
In December 2007 and January 8, a Idera SQL products via BitTorrent.
In January 2011 the "stolen source code" of Kaspersky Anti-Virus 2008 was published on the Pirate Bay.
On May 20, 2011, EVE Online's source code was published by someone on a GitHub repository. After being online for four days CCP issued a DMCA take-down request which was followed by GitHub.
In 2011 the source code of GunZ: The Duel v1.5 became available online.
In December 2011, the source code of the Solaris 11 operating system's kernel was leaked via BitTorrent.
In August 2014 S.T.A.L.K.E.R.: Clear Sky's X-Ray Engine source code (and its successor) became available on GitHub under a non-open-source license.
On December 29, 2015 the AmigaOS 3.1 source code leaked to the web, confirmed by the rights holder Hyperion Entertainment.
In January 2017 the source code of Opera's Presto Browser engine was leaked to GitHub. The source code was shortly after taken down with a DMCA notice.
In June 2017 part of Microsoft's Windows 10 source code leaked to the public.
End-of-life leaks by developers
Sometimes software developers themselves will leak their source code in an effort to prevent a software product from becoming abandonware after it has reached its end-of-life, allowing the community to continue development and support. Reasons for leaking instead of a proper release to public domain or as open source can include scattered or lost intellectual property rights. An example is the video game Falcon 4.0 which became available in 2000; another one is Dark Reign 2, which was released by an anonymous former Pandemic Studios developer in 2011. Another notable example is an archive of Infocom's video games source code which appeared from an anonymous Infocom source and was archived by the Internet Archive in 2008.