Researchers from segmentation solutions provider Guardicore have identified a series of vulnerabilities that could have been exploited by a hacker to turn a TV remote into a spying device.
The research focused on the XR11 remote provided by Comcast to Xfinity customers. The remote allows users to change channels, search for programs, and perform other actions using voice commands. Guardicore’s research analyzed the XR11 remote with the Xfinity X1 set-top box.
The first phase of the attack, which Guardicore has dubbed WarezTheRemote, focused on remotely pushing malicious firmware to a targeted remote. The device uses radio frequency (RF) rather than infrared (IR) to communicate with the set-top box. Since RF has a longer range, it made it possible for malicious actors to launch an attack from a significant distance.
Communications between the remote and the set-top box are encrypted, but the remote’s firmware failed to ensure that only encrypted responses were accepted for encrypted requests, allowing an attacker to send malicious responses in plain text.
Another aspect of the attack relied on the fact that the remote checked for firmware updates by querying the set-top box every 24 hours. The researchers found that an attacker could have impersonated the set-top box to inform the remote that a firmware update is available by exploiting the encryption-related flaw.
The researchers found a way not only to push malicious firmware to a remote by impersonating the box, but also to cause the box to enter a DoS condition to ensure that it did not interfere with the attack — uploading the firmware took roughly half an hour and the process could have been disrupted by interferences.
The experts reverse engineered the remote’s firmware and managed to make slight modifications that would enable an attacker to remotely trigger the microphone on the remote. The recorded audio was streamed over RF, allowing the attacker to spy on the user.
A WarezTheRemote attack could have been conducted using equipment that costs only a few dollars, but an RF receiver and a 16dBi antenna that cost a couple hundred dollars allowed the experts to conduct an attack from a distance of 65 feet and the remote picked up the victim’s voice from a distance of 15 feet. Guardicore believes the attack could have worked over even longer distances.
The findings were reported to Comcast in April and the company started rolling out patches on July 14. The vendor said version 22.214.171.124 of the firmware, which addresses the vulnerabilities, was pushed to all affected devices by September 24. The DoS flaw affecting the set-top box was also fixed.
“As Comcast has completed its remediation efforts, we know of no vulnerable devices at this time. Up until the fixes were released, though, every XR11 remote could have been attacked in this fashion. Besides leaving out the batteries, there was no effective way to mitigate it, either,” Guardicore said.