Twilio: Someone broke into our unsecured AWS S3 silo

ExclusiveTwilio today confirmed one or more miscreants sneaked into its unsecured cloud storage systems and modified a copy of the JavaScript SDK used by its customers.

The cloud communications giant detailed the intrusion to The Register after we were tipped off to the security blunder by a source who wished to remain anonymous. In short, someone was able to get into Twilio's Amazon Web Services S3 bucket, which was left unprotected and world-writable, and alter the TaskRouter v1.20 SDK to include "non-malicious" code that appeared designed primarily to track whether or not the modification worked.

"Twilio believes the security of our customers' accounts is of paramount importance," a spokesperson told us.

"We can confirm that the TaskRouter v1.20 SDK contained a non-malicious modification inserted by an external third party due to a misconfigured S3 bucket. We became aware of the incident and immediately worked to close the S3 misconfiguration and audit all S3 buckets.

"These measures were implemented within 12 hours to resolve the issue. We have no evidence at this time that any customer data was accessed by a bad actor. Furthermore, at no time did a malicious party have access to Twilio’s internal systems, code or data."

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The JavaScript SDK is Twilio's recommended method for linking your business events, such as incoming phone calls from customers and alerts from monitoring systems, to its TaskRouter platform , which routes calls and jobs to your staff. For instance, if someone who prefers to speak Spanish hits the "call me, I need help" button on your website, your web app uses the TaskRouter SDK to create a task, in this case "call this customer now," which is routed via a queue to a staffer who can speak Spanish and handle the call.

Our source warned us: "There's been a security incident at Twilio. Malicious JavaScript was added to the TaskRouter SDK for about 10 hours." When we pressed Twilio for more information on the nature of the "non-malicious" code it said was injected into the SDK, Twilio told us:

Specifically, the modification added code to the end of the TaskRouter.js v1.20 SDK that made an HTTP GET request to hxxps://gold.platinumus.top/track/awswrite?q=dmn and followed the URL returned in the HTML by that request.

Judging by that snippet, it looks as though this was a near-miss, and whoever accessed the system was simply probing around the codebase to see what they could change in the S3 bucket potentially ahead of any major or dangerous changes. And judging from the URL involved, it appears to be an attempt to install a payment-card skimmer – RiskIQ has spotted the same URL in other S3 buckets targeted by miscreants.

Given that TaskRouter.js serves as one of the link-ups between business applications and the TaskRouter service, this could have been a much worse attack. Twilio tells us it is planning to issue a report with more information on the incident in the coming days. In the meantime, if you recently downloaded and deployed a copy of the SDK, you might want to check you have a clean version. ®

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