The attack began on 5 April when hackers broke into Apache's Atlassian JIRA software used to track all its projects and any bugs that emerge.
They sent server admins a TinyURL link claiming they were having problems whilst browsing projects. When admins clicked on the link, it compromised their sessions and allowed the hackers to get hold of administrator rights.
By 9 April, the hackers had planted a password stealing programme and taken full control of JIRA, as well as Apache's Confluence and Bugzilla programmes.
"If you are a user of the Apache hosted JIRA, Bugzilla, or Confluence, a hashed copy of your password has been compromised," said a blog post from the Apache Infrastructure team.
It has warned users of any of these programs to change their passwords, especially if they logged in between 6-9 April.
It has also left those who had Atlassian accounts before July 2008 in danger as an old unencrypted database containing customer passwords was left online and could have been compromised.
He added: "The legacy customer database, with passwords stored in plain text, was a liability. Even though it wasn't active, it should have been deleted. There's no logical explanation for why it wasn't, other than as we moved off one project, and on to the next one, we dropped the ball and screwed up."
Apache is running JIRA on a proxy configuration for the meantime and has made a number of changes to make the server safer.
"We hope our disclosure has been as open as possible and true to the ASF spirit," concluded the Apache blog. "Hopefully others can learn from our mistakes."
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Jennifer Scott is a former freelance journalist and currently political reporter for Sky News. She has a varied writing history, having started her career at Dennis Publishing, working in various roles across its business technology titles, including ITPro. Jennifer has specialised in a number of areas over the years and has produced a wealth of content for ITPro, focusing largely on data storage, networking, cloud computing, and telecommunications.
Most recently Jennifer has turned her skills to the political sphere and broadcast journalism, where she has worked for the BBC as a political reporter, before moving to Sky News.