Updated A critical flaw in the Chrome extension of Grammarly – the grammar-checking software with online ads second only to Geico in terms of their ability to annoy – has left all 22 million users' personal records available to all.
The vulnerability, spotted on February 2 by Google Project Zero's Tavis Ormandy – allows any website to access "documents, history, logs, and all other data" associated with grammar pedants' Grammarly accounts if they use the browser plugin and browse to a malicious webpage. Poor coding in the extension allows peeps' authentication tokens to be grabbed by four lines of code on those evil websites.
"I'm calling this a high severity bug, because it seems like a pretty severe violation of user expectations," Ormandy reported. "Users would not expect that visiting a website gives it permission to access documents or data they've typed into other websites."
As a result, any website that a Grammarly Chrome extension user visits could scrape up their authentication tokens, and then access every document, note, or keystroke the app has recorded. Ormandy notified the app makers, and gave them a 90-day countdown to fix it.
To its credit, Grammarly didn’t sit on its hands. The developers fixed the issue over the weekend and, as of Monday morning, have pushed out a fix to all users.
We were made aware of a security issue with our extension on Friday and worked with Google to roll out a fix within a few hours.— Grammarly (@Grammarly) February 5, 2018
Thank you to @taviso and the team for finding and educating the community about the complexities of this bug. We will provide more updates soon.
"Grammarly had fixed the issue and released an update to the Chrome Web Store within a few hours, a really impressive response time," Ormandy said on Monday. "I've verified that Mozilla now also has the update, so users should be auto-updated to the fixed version. I'm calling this issue fixed." ®
Updated to add
A spokesperson for the plugin maker has been in touch to say:
Grammarly resolved a security bug reported by Google’s Project Zero security researcher, Tavis Ormandy, within hours of its discovery. At this time, Grammarly has no evidence that any user information was compromised by this issue. We’re continuing to monitor actively for any unusual activity. The security issue potentially affected text saved in the Grammarly Editor. This bug did not affect the Grammarly Keyboard, the Grammarly Microsoft Office add-in, or any text typed on websites while using the Grammarly browser extension. The bug is fixed, and there is no action required by Grammarly users.