More than a year ago, Bloomberg Business Weekly seized the field of cyber security with an explosive topic: ultra-micro motherboards in servers used by large technology companies such as Apple and Amazon were quietly embedded in rice-size chips so hackers could spy deep into these networks. Apple, Amazon and Supermicro have all vehemently denied the report. The NSA called it a false alarm. The World Congress of hackers awarded it two
But even if the story has not yet been confirmed, the security services warn that the possible supply chain attacks it describes are too real. After all, according to whistleblower Edward,
At the CS3sthlm security conference later this month, security researcher Monta Elkins will show how he can create a proof-of-concept version of the hardware hacker in his basement. He intends to prove to the world how easy it is for spies, criminals or underminers with the lowest skills to implant chips into enterprise IT devices with a low budget to provide them with invisible backdoor access. (Full disclosure: I will speak at the same meeting, which paid for my trip and provided participants with copies of my forthcoming book.) Just ordering a $150 hot air welding tool, a $40 microscope and some $2 chips online, Elkins can somehow change the Cisco firewall. He said that most IT administrators may not notice this, but they can give remote attackers deep control.
Nails in Firewall
Elkins found a ATtiny85 chip with an area of about 5 square millimeters on a $2 Digispark Arduino board. It's not the size of a grain of rice, but it's smaller than a fingernail. After writing the code to the chip, Elkins removes it from the Digispark board and welds it to the motherboard of the Cisco ASA 5505 firewall. He is installed in an inconspicuous place, does not require additional wiring, and allows the chip to access the serial port of the firewall.
The following figure shows the complexity of the fireproof wallboard
At the bottom of the Cisco ASA 5505 firewall motherboard, the red ellipse represents the 5 square millimeter chip added by Elkins.
Once the firewall is activated in the target's data center, Elkins programs his small stowaway chip to attack. It impersonates security administrators and connects their computers directly to the port to access the firewall configuration. The chip then triggers the firewall's password recovery function, creates a new administrator account, and gets access to the firewall settings. Elkins said he used Cisco's ASA 5505 firewall in the experiment because it was the cheapest firewall he had found on eBay. But he said any Cisco firewall that provides this recovery in the event of password loss works. Cisco said in a statement:
Once the malicious chip has access to these settings, Elkins says, his attack can change firewall settings so that hackers can remotely access devices, disable their security features, and allow hackers to access and see all connected device logs without alerting administrators.
Before Elkins'work, he tried to reproduce more accurately the kind of hardware hacker attacks Bloomberg described in its supply chain hijacking scenario. As part of a study published at the Chaos Computer Conference conference last December, Trammell Hudson, an independent security researcher, established a proof of concept for Supermicro PCB, which attempts to mimic the hacker technology described in Bloomberg stories. This means that a chip embedded on the super micro motherboard can access its board management controller (BMC), which is a component that allows remote management and provides hackers with deep control over the target server.
Hudson used to work at Sandia National Laboratory and now runs his own security consulting company. He found a point on the super-microboard where he could replace a tiny resistor with his own chip to change data in and out of the BMC in real time, an attack described by Bloomberg. Then, he used so-called field reprogrammable gate arrays (a kind of reprogrammable chip sometimes used for prototype custom chip design) to act as malicious interception components.
The FPGA area of Hudson is less than 2.5 square millimeters, which is only slightly larger than the 1.2mm resistor it replaces on the superminiature board. But in the real proof-of-concept style, he says, he doesn't actually try to hide the chip, but connects it to the board with a bunch of wiring and crocodile clips. However, Hudson believes that a real attacker has the resources to make custom chips
In a statement, Ultramicro said:
But Elkins points out that his firewall-based attack is far from that complicated. It doesn't need that custom chip at all. It only costs $2 a chip. Elkins said:
Both Elkins and Hudson stressed that their work was not to confirm Bloomberg's supply chain attack story about implanting microchips into devices. They don't even think that this may be a common attack; both researchers point out that, although not necessarily the same concealment, traditional software attacks can usually give hackers the same access rights.
But both Elkins and Hudson agree that hardware-based espionage through the hijacking of the supply chain is still a technical reality and is easier to implement than many security administrators around the world realize.