PlayStation Portable homebrew

PlayStation Portable homebrew refers to the process of using exploits and hacks to execute unsigned code on the PlayStation Portable (PSP).

Soon after the PSP was released, hackers began to discover exploits in the PSP that could be used to run unsigned code on the device. Sony released version 1.51 of the PSP firmware in May 2005 to plug the holes that hackers were using to gain access to the device. On 15 June 2005 the hackers distributed the cracked code of the PSP on the internet. Hackers refused to apply updates which would render their hacks unusable so Sony attempted to convince users that there was a benefit to upgrading by including new features in the firmware updates, such as a web browser, and not just security patches to plug the vulnerabilities. BusinessWeek dubbed this the "carrot-and-stick" approach.

In August 2005 Sony released version 2.0 of the firmware which included the web browser, file compatibility updates and other features. Hackers and other homebrew enthusiasts then encountered the first trojan for the PSP. Symantec called this trojan "Trojan.PSPBrick". Users attempting to downgrade their PSP using this software instead found that it was rendered inoperable as this software deleted mandatory/important system files. Over the course of 2005 Sony released six different versions of the firmware and hackers typically responded to it by downgrading to avoid the new security updates.

In Mid-2006, after several months of problems in defeating the PSP's firmware a file was posted online which allowed new PSPs running firmware version 2.6 to downgrade to 1.5 so they could then be hacked using older methods. This reportedly caused more buzz in the community than any recent official offerings for the device.

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Wikipedia