Remote attackers can cause thousands of Brother printers to temporarily stop working by exploiting an unpatched vulnerability discovered recently by researchers at Trustwave.
According to an advisory published by the security firm, the flaw is related to an embedded httpd server named Debut that some Brother products use to host their web interfaces. The security hole is tracked as CVE-2017-16249 and it affects version 1.20 and earlier of the Debut software.
A remote attacker can exploit the security hole by sending a specially crafted HTTP request to the targeted device. The request causes the server to hang until it eventually responds with an HTTP 500 error. During the time the server is hung, users cannot perform print jobs over the network and the web interface becomes inaccessible.
Trustwave noted that an attacker can generate a DoS condition for an extended period of time by continuously sending malicious requests to a device. The security firm has identified more than 16,000 vulnerable printers that can be attacked remotely over the Internet.
“Some people dismiss Denial of Service attacks as a mere nuisance, but they can tie up resources and reduce productivity at any organization,” a Trustwave researcher explained in a blog post. “They can also be used as a part of an in-person attack on a organization. For instance, an attacker can launch a Denial of Service like this one and then show up at the organization as the ‘technician’ called to fix the problem. Impersonating a technician would allow the attacker direct physical access to IT resources that they might never have been able to access remotely.”
Trustwave has been trying to inform Brother about the vulnerability since September, but it decided to make its findings public, along with proof-of-concept (PoC) code, after all attempts to contact the vendor failed. The flaw remains unpatched, the company said.
Brother is not the only company whose printers are affected by vulnerabilities. A report published early this year showed that several devices from HP, Brother, Lexmark, Dell, Samsung, Konica, OKI and Kyocera had at least one flaw, including ones that could be exploited for DoS attacks or to obtain sensitive information.
Last year, a researcher demonstrated the risks associated with unprotected printers by getting thousands of devices around the world to print anti-Semitic flyers.