Threat Intelligence

6/6/2016
07:30 AM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
100%
0%

Researchers Demo How To Build Nearly Invisible Backdoor In Computer Chips

Modification almost impossible to catch in post-fab tests says University of Michigan researchers in report that details proof-of-concept attack

Researchers at the University of Michigan in Ann Arbor have demonstrated how someone could install a virtually undetectable backdoor on a microprocessor during the fabrication process that could be exploited later to gain complete access to systems running the tampered chips.

The method, detailed in a technical paper innocuously titled ‘Analog Malicious Hardware’, was presented recently at the IEEE Symposium on Security and Privacy. The researchers described it as the first fabrication-time processor attack of its kind and the first to demonstrate an analog attack that is substantially smaller and stealthier than a digital attack.

The attack involves the addition of a single, booby-trapped logic gate to a chip that is ready for fabrication and the use of an extremely stealthy process for triggering changes in the gate’s functionality so it eventually acts in a malicious manner. The attack method is virtually undetectable because it involves no significant changes to the chip’s circuitry or design, according to the researchers.

A logic gate is sort of an electronic on-off switch consisting of transistors and wires that controls the operations of a chip. Modern microprocessors can have hundreds of millions of logic gates. The attack demonstrated by the researchers involves the use of a single such gate, with a capacitor inside capable of storing a minute electrical charge. The gate is designed in such a manner that its function can be flip-flopped—or switched from off to on—when the accumulated charge in the capacitor reaches a certain pre-defined threshold.

The Michigan University research paper describes a method where the rogue gate can be placed in such a way on the chip that it can siphon charges from a nearby wire when certain commands are issued. “If the wire toggles infrequently, the capacitor voltage stays near zero volts due to natural charge leakage,” the researchers said in their report. However, when the wire is toggled frequently the capacitor in the rogue gate begins to charge and eventually reaches a voltage threshold that causes the gate to flip to a malicious state.  

Attackers can craft attack triggers that ensure the modification to a malicious state happens only when a sequence of specific and unlikely events happens. As a result even the most diligent post-fabrication tests are unlikely to catch it, the researchers said.

The researchers demonstrated the feasibility of building such backdoors in microprocessors by fabricating a chip based on open-RISC 1200 technology. “Experimental results show that our attacks work, show that our attacks elude activation by a diverse set of benchmarks, and suggest that our attacks evade known defenses,” they noted in the paper.

Modern chip design companies can open themselves up to such issues when they use third parties to fabricate their designs, the researchers said. Attackers can make minute changes to the chip and set it up so the modifications become malicious only when a specific and rare sequence of events happen, thereby evading detection during post-fabrication tests.

Yonatan Zunger, head of infrastructure for Google Assistant described the proof-of-concept as one of the “most demonically clever” computer security attacks in many years. “It's an attack which can be performed by someone who has access to the microchip fabrication facility, and it lets them insert a nearly undetectable backdoor into the chips themselves,” Zunger said in a Google+ post.

Among those who might want to attempt such an attack would be state-level actors, he said. “I don't know if I want to guess how many three-letter agencies have already had the same idea, or what fraction of chips in the wild already have such a backdoor in them.”

Related content:

Jai Vijayan is a seasoned technology reporter with over 20 years of experience in IT trade journalism. He was most recently a Senior Editor at Computerworld, where he covered information security and data privacy issues for the publication. Over the course of his 20-year ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Jon M. Kelley
50%
50%
Jon M. Kelley,
User Rank: Moderator
6/7/2016 | 11:14:32 AM
Many complex chips have backdoors built-in by design
Many complex chips have password protected backdoors built-in by design.  Unfortunately, as a British researcher demonstrated, since the password is cast in the silicon chip, once you dig it out, you have it for all chips in that line. 
ba956
50%
50%
ba956,
User Rank: Apprentice
6/6/2016 | 12:20:33 PM
Supply chain risks ...
Accountability - What prevents large chip manufacturers from allowingg this is their commitment to their brand and reputation. Intel and AMD for example would face huge damage to their brand if it were proven they had allowed such a "flaw" so make it into production.

However, if your supply chain has three or four subcontractors passing high level requirements into silicon design which is then shipped off to a botique foundry/ fab shop -then your product may be exposed to insertion of unwanted features.

Government entities do something similar in interception technology orders and placing backdoors into BIOS, or even xmitters into USB and video cables. 

 
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
The Year in Security 2018
This Dark Reading Tech Digest explores the biggest news stories of 2018 that shaped the cybersecurity landscape.
Flash Poll
How Enterprises Are Attacking the Cybersecurity Problem
How Enterprises Are Attacking the Cybersecurity Problem
Data breach fears and the need to comply with regulations such as GDPR are two major drivers increased spending on security products and technologies. But other factors are contributing to the trend as well. Find out more about how enterprises are attacking the cybersecurity problem by reading our report today.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2018-20735
PUBLISHED: 2019-01-17
** DISPUTED ** An issue was discovered in BMC PATROL Agent through 11.3.01. It was found that the PatrolCli application can allow for lateral movement and escalation of privilege inside a Windows Active Directory environment. It was found that by default the PatrolCli / PATROL Agent application only...
CVE-2019-0624
PUBLISHED: 2019-01-17
A spoofing vulnerability exists when a Skype for Business 2015 server does not properly sanitize a specially crafted request, aka "Skype for Business 2015 Spoofing Vulnerability." This affects Skype.
CVE-2019-0646
PUBLISHED: 2019-01-17
A Cross-site Scripting (XSS) vulnerability exists when Team Foundation Server does not properly sanitize user provided input, aka "Team Foundation Server Cross-site Scripting Vulnerability." This affects Team.
CVE-2019-0647
PUBLISHED: 2019-01-17
An information disclosure vulnerability exists when Team Foundation Server does not properly handle variables marked as secret, aka "Team Foundation Server Information Disclosure Vulnerability." This affects Team.
CVE-2018-20727
PUBLISHED: 2019-01-17
Multiple command injection vulnerabilities in NeDi before 1.7Cp3 allow authenticated users to execute code on the server side via the flt parameter to Nodes-Traffic.php, the dv parameter to Devices-Graph.php, or the tit parameter to drawmap.php.