Hackers can exploit USB devices to trigger undetectable attacks

Pierluigi Paganini August 01, 2014

A popular security researcher revealed that bad actors can tap into USB Devices to conduct attacks non detectable with known security defenses.

Security experts demonstrated that USB devices can be used to compromise personal computers in a potential new type of attacks that evade all actual security protections.

Karsten Nohl, chief scientist with Berlin’s SR Labs, discovered that bad actors could exploit this new class of attacks loading malicious software low-cost computer chips that control the functions of USB devices.

The researchers point a series of flaws in the software used to run tiny electronic components, these components are usually designed without protections against tampering with their code.

Hackers can uncover such flaws and exploit them creating serious problems to the targeted architecture.

“You cannot tell where the virus came from. It is almost like a magic trick,” said Nohl.

Nohl explained that his team has written malicious code and deployed it into USB control chips used in thumb drives and smartphones, at this point it is sufficient that victims connect the USB device to a computer to trigger the execution of malicious software. Antivirus software are not able to detect malicious firmware that controls USB devices, the code inserted with this method can be used for many purposes, including spy on communications, data tampering and log keystrokes.

Nohl and his colleague Jakob Lell, a security researcher at SR Labs, will present the results of his study at the incoming Black Hat hacking conference in Las Vegas, he has anticipated the title of their a presentation, “Bad USB – On Accessories that Turn Evil.

“USB has become so commonplace that we rarely worry about its security implications. USB sticks undergo the occasional virus scan, but we consider USB to be otherwise perfectly safe — until now.

This talk introduces a new form of malware that operates from controller chips inside USB devices. USB sticks, as an example, can be reprogrammed to spoof various other device types in order to take control of a computer, exfiltrate data, or spy on the user.” is reported on the  SR Labs website. 

At next BlackHat, the researchers will demonstrate how to hack a system from USB and a self-replicating USB virus not detectable with current defenses.

“We then dive into the USB stack and assess where protection from USB malware can and should be anchored.” the researcher added.

usb chip hacking 2

Nohl explained that during his tests, he was able to gain remote access to a computer using a malicious code that, once the USB is connected, instructs the targeted system to download a malware. The code deceives the PC making it believe that the malicious instructions are originated by a keyboard or any other USB device.

Similar attacks could be very effective against systems deployed in critical infrastructure and consumer electronics, for this reason Nohl speculated that intelligence agencies like the National Security Agency have already exploited these hacking techniques.

Nohl is very popular within the hacking community, at the last edition of the Black Hat conference, he demonstrated a method to remotely hack SIM cards on mobile devices.

The team of experts at SR Labs succeeded to infect with their technique chips designed by the major manufacturer Taiwan’s Phison Electronics Corp, and placed them into USB memory drives and Android smartphones. As explained by Nohl, products of other manufactures could be potentially hacked with the this method, the chips produced by the manufactures, once infected, could be used to infect any kind of device that connects via USB.

“The sky is the limit. You can do anything at all,” he said.

At time I’m writing Phison neither Google replied to the requests for comment made by the researchers.

The researcher also explained that the technique his team used could also be used by a bad actor to change victim network settings with the purpose to route Internet traffic through malicious servers, potentially the targeted machine could be used to be completely controlled by attackers, also to attack other machines.

“Now all of your USB devices are infected. It becomes self-propagating and extremely persistent,” Nohl said. “You can never remove it.”

I believe that manufacturers have to take in serious consideration this study in order to improve the security of the product they commercialize.

Pierluigi Paganini

Security Affairs –  (USB, chips)

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