5 minutes with a Thunderbolt machine leaves it completely open using Thunderspy – evil maids don’t need much knowledge

Thunderspy targets devices with a Thunderbolt port. If your computer has such a port, an attacker who gets brief physical access to it can read and copy all your data, even if your drive is encrypted and your computer is locked or set to sleep.

Thunderspy is stealth, meaning that you cannot find any traces of the attack. It does not require your involvement, i.e., there is no phishing link or malicious piece of hardware that the attacker tricks you into using. Thunderspy works even if you follow best security practices by locking or suspending your computer when leaving briefly, and if your system administrator has set up the device with Secure Boot, strong BIOS and operating system account passwords, and enabled full disk encryption. All the attacker needs is 5 minutes alone with the computer, a screwdriver, and some easily portable hardware.

We have found 7 vulnerabilities in Intel’s design and developed 9 realistic scenarios how these could be exploited by a malicious entity to get access to your system, past the defenses that Intel had set up for your protection.

We have developed a free and open-source tool, Spycheck, to determine if your system is vulnerable. If it is found to be vulnerable, Spycheck will guide you to recommendations on how to help protect your system.


These vulnerabilities lead to nine practical exploitation scenarios. In an evil maid threat model and varying Security Levels, we demonstrate the ability to create arbitrary Thunderbolt device identities, clone user-authorized Thunderbolt devices, and finally obtain PCIe connectivity to perform DMA attacks. In addition, we show unauthenticated overriding of Security Level configurations, including the ability to disable Thunderbolt security entirely, and restoring Thunderbolt connectivity if the system is restricted to exclusively passing through USB and/or DisplayPort. We conclude with demonstrating the ability to permanently disable Thunderbolt security and block all future firmware updates.

All Thunderbolt-equipped systems shipped between 2011-2020 are vulnerable. Some systems providing Kernel DMA Protection, shipping since 2019, are partially vulnerable. The Thunderspy vulnerabilities cannot be fixed in software, impact future standards such as USB 4 and Thunderbolt 4, and will require a silicon redesign. Users are therefore strongly encouraged to determine whether they are affected using Spycheck, a free and open-source tool we have developed that verifies whether their systems are vulnerable to Thunderspy. If it is found to be vulnerable, Spycheck will guide users to recommendations on how to help protect their system.


The Thunderspy vulnerabilities have been discovered and reported by Björn Ruytenberg. Please cite this work as:

Björn Ruytenberg. Breaking Thunderbolt Protocol Security: Vulnerability Report. 2020. https://thunderspy.io/assets/reports/breaking-thunderbolt-security-bjorn-ruytenberg-20200417.pdf

Source: Thunderspy – When Lightning Strikes Thrice: Breaking Thunderbolt 3 Security

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