Thunderbolt devices can infect MacBooks with persistent rootkits

The rogue code will run in the boot ROM and will be hard to detect or remove, a researcher said

Attackers can infect MacBook computers with highly persistent boot rootkits by connecting malicious devices to them over the Thunderbolt interface.

The attack, dubbed Thunderstrike, installs malicious code in a MacBook's boot ROM (read-only memory), which is stored in a chip on the motherboard. It was devised by a security researcher named Trammell Hudson based on a two-year old vulnerability and will be demonstrated next week at the 31st Chaos Communication Congress in Hamburg.

"It is possible to use a Thunderbolt Option ROM to circumvent the cryptographic signature checks in Apple's EFI firmware update routines," Hudson said in the description of his upcoming presentation. "This allows an attacker with physical access to the machine to write untrusted code to the SPI flash ROM on the motherboard and creates a new class of firmware bootkits for the MacBook systems."

Malicious code installed in the MacBook boot ROM will be executed before the OS is loaded, meaning it can patch the OS kernel and have complete control over the system. It also means that reinstalling Mac OS X will not remove the bootkit and neither will replacing the hard disk drive, because the malicious code is not stored on it.

The bootkit can even replace Apple's cryptographic key stored in the ROM with one generated by the attacker, preventing any future legitimate firmware updates from Apple, the researcher said in a blog post.

Firmware updates are supposed to be signed, but the vulnerability exploited by this attack allows that mechanism to be bypassed.

"Additionally, other Thunderbolt devices' Option ROMs are writable from code that runs during the early boot and the bootkit could write copies of itself to new Thunderbolt devices," the researcher said. "The devices remain functional, which would allow a stealthy bootkit to spread across air-gap security perimeters through shared Thunderbolt devices."

This worm-like spreading capability is similar to that of BadUSB, a stealthy malware attack demonstrated earlier this year at the Black Hat security conference that can infect the firmware of USB devices and then use them to compromise other computers.

Security researchers have also previously demonstrated methods to bypass Secure Boot, a security mechanism of the Unified Extensible Firmware Interface (UEFI) -- the BIOS replacement in modern computers -- in order to install bootkits.

Join the Good Gear Guide newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags intrusionApplesecurityDesktop securityExploits / vulnerabilitiesmalware

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Armand Abogado

HP OfficeJet 250 Mobile Printer

Wireless printing from my iPhone was also a handy feature, the whole experience was quick and seamless with no setup requirements - accessed through the default iOS printing menu options.

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?