GitHub on Monday informed clients that it had found what it described as an “extremely rare, but potentially serious” security bug identified with how some authenticated sessions were handled. On 8th March GitHub signed out all clients that were signed in before March 8th. The precautionary measure was taken seven days after the organization had gotten an underlying report of dubious conduct, from an external party.
The Microsoft-owned software development platform said the bug was found on March 2 and an underlying patch was carried out on March 5. A subsequent fix was delivered on March 8 and on the evening of that very day the organization chose to invalidate all authenticated sessions to completely eliminate the possibility of exploitation. On Friday, the GitHub team has remediated the security flaw and kept on analyzing the situation over the weekend. The vulnerability being referred to, could be misused in extremely rare circumstances, when a rare condition would happen during the backend request handling process, permitting the session cookie of a logged-in GitHub client to be sent to the software of another client, giving the latter access to the former user’s account.
“It is important to note that this issue was not the result of compromised account passwords, SSH keys, or personal access tokens (PATs) and there is no evidence to suggest that this was the result of a compromise of any other GitHub systems,” says Mike Hanley, GitHub’s recently appointed chief security officer. “Instead, this issue was due to the rare and isolated improper handling of authenticated sessions. Further, this issue could not be intentionally triggered or directed by a malicious user.”
The organization declared that the bug existed on GitHub.com for less than two weeks and it doesn't resemble some other GitHub.com assets or products were impacted as a result of this bug. "We believe that this session misrouting occurred in less than 0.001% of authenticated sessions on GitHub.com. For the very small population of accounts that we know to be affected by this issue, we’ve reached out with additional information and guidance,” continues Hanley in the announcement.
The organization is still analyzing if any project repositories or source code were messed with because of this vulnerability as this kind of authentication vulnerabilities could pave the way for software supply-chain attacks.
