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: Apprentice
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. 

 
Game Change: Meet the Mach37 Fall Startups
Ericka Chickowski, Contributing Writer, Dark Reading,  10/18/2017
Veracode: 75% Of Apps Have at Least One Vulnerability on Initial Scan
Jai Vijayan, Freelance writer,  10/20/2017
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Security Vulnerabilities: The Next Wave
Just when you thought it was safe, researchers have unveiled a new round of IT security flaws. Is your enterprise ready?
Flash Poll
[Strategic Security Report] How Enterprises Are Attacking the IT Security Problem
[Strategic Security Report] How Enterprises Are Attacking the IT Security Problem
Enterprises are spending more of their IT budgets on cybersecurity technology. How do your organization's security plans and strategies compare to what others are doing? Here's an in-depth look.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2017-0290
Published: 2017-05-09
NScript in mpengine in Microsoft Malware Protection Engine with Engine Version before 1.1.13704.0, as used in Windows Defender and other products, allows remote attackers to execute arbitrary code or cause a denial of service (type confusion and application crash) via crafted JavaScript code within ...

CVE-2016-10369
Published: 2017-05-08
unixsocket.c in lxterminal through 0.3.0 insecurely uses /tmp for a socket file, allowing a local user to cause a denial of service (preventing terminal launch), or possibly have other impact (bypassing terminal access control).

CVE-2016-8202
Published: 2017-05-08
A privilege escalation vulnerability in Brocade Fibre Channel SAN products running Brocade Fabric OS (FOS) releases earlier than v7.4.1d and v8.0.1b could allow an authenticated attacker to elevate the privileges of user accounts accessing the system via command line interface. With affected version...

CVE-2016-8209
Published: 2017-05-08
Improper checks for unusual or exceptional conditions in Brocade NetIron 05.8.00 and later releases up to and including 06.1.00, when the Management Module is continuously scanned on port 22, may allow attackers to cause a denial of service (crash and reload) of the management module.

CVE-2017-0890
Published: 2017-05-08
Nextcloud Server before 11.0.3 is vulnerable to an inadequate escaping leading to a XSS vulnerability in the search module. To be exploitable a user has to write or paste malicious content into the search dialogue.