September 2, 2020
A vast majority of IoT hardware in homes and offices is vulnerable to attacks that allow devices to be easily taken over and manipulated for malicious purposes.
Few device manufacturers or security researchers are paying nearly as much attention to this issue as they are to software vulnerabilities, according to Marc Rogers, white hat hacker and executive director of cybersecurity at Okta.
In a presentation at Okta's virtual Disclosure security conference on Wednesday, Rogers described most IoT hardware as having very weak to no protections against attacks aimed at prying secrets from device firmware.
Rogers claimed he was able to gain complete root level access, including the ability to re-flash firmware, on 10 out of 12 devices he tested. Most were cracked in less than five minutes, he said. The products he tested included home routers, switches, card access readers, and other commonly installed Internet-connected devices.
The issue with all of these systems, and indeed all IoT devices, is that most proprietary information about the device — including certificates, keys, and communication protocols — is typically stored in poorly secured flash memory. Anyone with access to an IoT device and some basic knowledge of hardware hacking can easily access the firmware and look for data, including vulnerabilities that could potentially allow them to launch attacks against similar devices without requiring physical access, Rogers explained.
According to Rogers, the techniques he used to hack into these devices are well understood and have been around for a long time. "What is less known is how easily accessible and devastatingly effective they are," he explained. "I don't think I have seen one IoT device where at least one of these techniques doesn't apply," Rogers said in an interview with Dark Reading.
In his talk, Rogers outlined a few approaches that are available to hackers to pry proprietary information from an IoT device and take control of it in a manner not intended by the device manufacturer.
The UART and JTAG Routes
One of the easiest methods is to gain access to UART, or Universal Asynchronous Receiver/Transmitter, a serial interface used for diagnostic reporting and debugging in all IoT products, among other things. An attacker can use the UART to gain root shell access to an IoT device and then download the firmware to learn its secrets and inspect for weaknesses.
"UART is only supposed to be used by the manufacturer. When you get access to it, in most cases you get complete root access," Rogers said.
Protecting access to UART, or at least configuring it against interactive access, should be a fairly straightforward task for manufacturers; however, most don't make the effort. "They simply allow you to have complete interactive shell. It is the easiest way to hack every piece of IoT hardware," Rogers noted. Several devices even have UART pin names labeled on the board so it is easy to find the interface. Multiple tools are available to help find them if they are not labeled.
Another, only slightly more challenging, route to completely pwning an IoT device is via JTAG, a microcontroller-level interface that is used for multiple purposes including testing integrated circuits and programming flash memory. As with UART, an attacker with access to JTAG can alter flash memory, access debug tools, and extract other proprietary information about the device.
Though the JTAG interface can be slightly harder to find than UART, it still is easy enough to discover for those who know what to look for or have the tools to do it for them, according to Rogers. There are steps that manufacturers can take to lock JTAG down, and indeed they do for some modern devices, but most still provide relatively easy access to JTAG, he said.
When manufacturers have tried to make access to UART and other interfaces harder, their attempts have been amateurish. As one example, Rogers pointed to an IoT device manufacturer that disguised the UART interface as an HDMI port. He cited another example in which the programming interface for a microcontroller, which stored the master key for a widely used access card reader, was hidden under a piece of black electrical tape at the back.
"Hardware manufacturers have got to stop trying to hide these hardware problems," he emphasized.
Just as security researchers' intense scrutiny on smart car technologies is driving change, there is need for similar focus on IoT hardware weaknesses. Technologies are available that allow manufacturers to build more secure hardware, and costs to do so are dropping. "We really don't have much excuse not to implement some security into hardware," Rogers said.
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