Slack only took five hours to fix bug that could have allowed hackers to hijack your account

Frans Rosén, a security researcher at Detectify, has been awarded $3,000 from Slack after uncovering a serious vulnerability that could have helped hackers to seize control of users’ accounts.

As Threatpost reports, Rosén discovered flaws in Slack’s code that ultimately lead to a method of stealing a user’s private token, and gaining unauthorised access to accounts:

The researcher eventually came up with an exploit that allowed him to steal Slack tokens. To get this done, he built a malicious page specifically designed to pick up and store your token. When clicked, the malicious page proceeds to open a Slack call, which in turn initiates a WebSocket reconnect pointed at his rogue server.

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Of course, this methodology really requires a Slack user to be specifically targeted, and for that targeted user to click on a link or deliberately visit a boobytrapped webpage, containing the code that begins the attack.

Nonetheless, this isn’t the type of vulnerability that any security-conscious software firm wants lying around waiting to be abused, and Rosén praised Slack’s response for… err… not being slack in its response.

I sent the report to Slack on a Friday evening. They responded 33 minutes after my initial report and had a fix out 5 hours after that. Amazing.

I agree. It’s a great response that should set an example for other technology companies. And, remember, this was on a Friday afternoon.

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Graham Cluley •   @gcluley

Graham Cluley is a veteran of the cybersecurity industry, having worked for a number of security companies since the early 1990s when he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows. Now an independent analyst, he regularly makes media appearances and is an international public speaker on the topic of cybersecurity, hackers, and online privacy. Follow him on Twitter, Mastodon, Threads, Bluesky, or drop him an email.