Simon Willison’s Weblog

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Items tagged github, security in 2021

Filters: Year: 2021 × github × security × Sorted by date


Behind GitHub’s new authentication token formats (via) This is a really smart design. GitHub’s new tokens use a type prefix of “ghp_” or “gho_” or a few others depending on the type of token, to help support mechanisms that scan for accidental token publication. A further twist is that the last six characters of the tokens are a checksum, which means token scanners can reliably distinguish a real token from a coincidental string without needing to check back with the GitHub database. “One other neat thing about _ is it will reliably select the whole token when you double click on it”—what a useful detail! # 5th April 2021, 9:28 pm

How we found and fixed a rare race condition in our session handling. GitHub had a terrifying bug this month where a user reported suddenly being signed in as another user. This is a particularly great example of a security incident report, explaining how GitHub identified the underlying bug, what caused it and the steps they are taking to ensure bugs like that never happen in the future. The root cause was a convoluted sequence of events which could cause a Ruby Hash to be accidentally shared between two requests, caused as a result of a new background thread that was introduced as a performance optimization. # 18th March 2021, 11:06 pm

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