Data From Deleted GitHub Repos May Not Actually Be Deleted, Researchers Claim

Thomas Claburn reports via The Register: Researchers at Truffle Security have found, or arguably rediscovered, that data from deleted GitHub repositories (public or private) and from deleted copies (forks) of repositories isn't necessarily deleted. Joe Leon, a security researcher with the outfit, said in an advisory on Wednesday that being able to access deleted repo data -- such as APIs keys -- represents a security risk. And he proposed a new term to describe the alleged vulnerability: Cross Fork Object Reference (CFOR). "A CFOR vulnerability occurs when one repository fork can access sensitive data from another fork (including data from private and deleted forks)," Leon explained.

For example, the firm showed how one can fork a repository, commit data to it, delete the fork, and then access the supposedly deleted commit data via the original repository. The researchers also created a repo, forked it, and showed how data not synced with the fork continues to be accessible through the fork after the original repo is deleted. You can watch that particular demo [here].

According to Leon, this scenario came up last week with the submission of a critical vulnerability report to a major technology company involving a private key for an employee GitHub account that had broad access across the organization. The key had been publicly committed to a GitHub repository. Upon learning of the blunder, the tech biz nuked the repo thinking that would take care of the leak. "They immediately deleted the repository, but since it had been forked, I could still access the commit containing the sensitive data via a fork, despite the fork never syncing with the original 'upstream' repository," Leon explained. Leon added that after reviewing three widely forked public repos from large AI companies, Truffle Security researchers found 40 valid API keys from deleted forks. GitHub said it considers this situation a feature, not a bug: "GitHub is committed to investigating reported security issues. We are aware of this report and have validated that this is expected and documented behavior inherent to how fork networks work. You can read more about how deleting or changing visibility affects repository forks in our [documentation]."

Truffle Security argues that they should reconsider their position "because the average user expects there to be a distinction between public and private repos in terms of data security, which isn't always true," reports The Register. "And there's also the expectation that the act of deletion should remove commit data, which again has been shown to not always be the case."

Read more of this story at Slashdot.