Cybercriminals are abusing a widespread lack of authentication within the customer support platform Zendesk to flood focused electronic mail inboxes with menacing messages that come from lots of of Zendesk company prospects concurrently.
Zendesk is an automatic assist desk service designed to make it easy for individuals to contact corporations for buyer assist points. Earlier this week, KrebsOnSecurity began receiving 1000’s of ticket creation notification messages by way of Zendesk in fast succession, every bearing the identify of various Zendesk prospects, comparable to CapCom, CompTIA, Discord, GMAC, NordVPN, The Washington Submit, and Tinder.
The abusive missives despatched by way of Zendesk’s platform can embody any topic line chosen by the abusers. In my case, the messages variously warned a couple of supposed legislation enforcement investigation involving KrebsOnSecurity.com, or else contained private insults.
Furthermore, the automated messages which might be despatched out from this kind of abuse all come from buyer domains — not from Zendesk. Within the instance under, replying to any of the junk buyer assist responses from The Washington Submit’s Zendesk set up exhibits the reply-to tackle is assist@washpost.com.
Certainly one of dozens of messages despatched to me this week by The Washington Submit.
Notified concerning the mass abuse of their platform, Zendesk mentioned the emails had been ticket creation notifications from buyer accounts that configured their Zendesk occasion to permit anybody to submit assist requests — together with nameless customers.
“Some of these assist tickets might be a part of a buyer’s workflow, the place a previous verification just isn’t required to permit them to have interaction and make use of the Help capabilities,” mentioned Carolyn Camoens, communications director at Zendesk. “Though we advocate our prospects to allow solely verified customers to submit tickets, some Zendesk prospects desire to make use of an nameless atmosphere to permit for tickets to be created as a result of numerous enterprise causes.”
Camoens mentioned requests that may be submitted in an nameless method may make use of an electronic mail tackle of the submitter’s alternative.
“Nevertheless, this methodology will also be used for spam requests to be created on behalf of third celebration electronic mail addresses,” Camoens mentioned. “If an account has enabled the auto-responder set off primarily based on ticket creation, then this enables for the ticket notification electronic mail to be despatched from our buyer’s accounts to those third events. The notification may also embody the Topic added by the creator of those tickets.”
Zendesk claims it makes use of fee limits to stop a excessive quantity of requests from being created without delay, however these limits didn’t cease Zendesk prospects from flooding my inbox with 1000’s of messages in just some hours.
“We acknowledge that our programs had been leveraged in opposition to you in a distributed, many-against-one method,” Camoens mentioned. “We’re actively investigating further preventive measures. We’re additionally advising prospects experiencing this kind of exercise to comply with our normal safety greatest practices and configure an authenticated ticket creation workflow.”
In the entire circumstances above, the messaging abuse wouldn’t have been attainable if Zendesk prospects validated assist request electronic mail addresses previous to sending responses. Failing to take action might make it simpler for Zendesk shoppers to deal with buyer assist requests, but it surely additionally permits ne’er-do-wells to sully the sender’s model in service of disruptive and malicious electronic mail floods.
