The Smallest Fix With The Biggest Impact [Skips VS Technology Edition]

This is a submission for DEV's Summer Bug Smash: Smash Stories powered by Sentry . Remember that one Regular Show episode where Skips tried to destroy the park's computer because it caught the Error 220 bug? He took one look at it, picked up a sledgehammer and said the line we’ve all felt as devs: “ There’s something evil in that computer. We gotta smash it ”. In the cartoon, they literally smash the computer and this works to fix the bug. In real life? We don’t get sledgehammers. We get Github PRs. Last week, I almost felt like Skips. I found a one-line bug in an open source repo that could’ve broken Instagram webhook security. No hammer, no explosion, just one misindented ‘if’ statement and a missing test. This is the story of how the smallest fix had the biggest impact. -The Challenge So what was my Error 220 ? While contributing to the corsair open-source repo, I found a security breach in the Instagram webhook handler. Something about the verification flow felt off, so I started tracing it line by line. The code called timingSafeEqual but the result was indecisive. I took an extensive look at it and that's when I saw it- The if statement meant to guard the check was there, but timingSafeEqual was indented wrong. It was meant to return the result of timingSafeEqual to accept or reject the request, but it fell through instead. Although it was running, its return value wasn’t being used to control the flow. This bug was tiny-one mis-indented line- but it had a great impact. In JS, it is not considered an error and so it’s easy to miss. Webhook security relies on a signature check to prove a request. If timingSafeEqual isn’t actually enforcing it, an attacker could forge a webhook and it would be accepted. The entire protection could fall apart over one tab. View PR #759 -The Fix In fixing it, I opened PR#759 to correct the indentation so crypto.timingSafeEqual would be inside the if block and its boolean result would decide whether to return true or false . Prior