The BIOS boots a computer and helps load the operating system. By infecting this core software, which operates below antivirus and other security products and therefore is not usually scanned by them, spies can plant malware that remains live and undetected even if the computer's operating system were wiped and re-installed.
Although most BIOS have protections to prevent unauthorized modifications, the researchers were able to bypass these to reflash the BIOS and implant their malicious code.
Because many BIOS share some of the same code, they were able to uncover vulnerabilities in 80 percent of the PCs they examined, including ones from Dell, Lenovo and HP. The vulnerabilities, which they're calling incursion vulnerabilities, were so easy to find that they wrote a script to automate the process and eventually stopped counting the vulns it uncovered because there were too many.
Kallenberg said an attacker would need to already have remote access to a compromised computer in order to execute the implant and elevate privileges on the machine through the hardware. Their exploit turns down existing protections in place to prevent re-flashing of the firmware, enabling the implant to be inserted and executed.
The devious part of their exploit is that they've found a way to insert their agent into System Management Mode, which is used by firmware and runs separately from the operating system, managing various hardware controls. System Management Mode also has access to memory, which puts supposedly secure operating systems such as Tails in the line of fire of the implant.
From the Register:
"Because almost no one patches their BIOSes, almost every BIOS in the wild is affected by at least one vulnerability, and can be infected," Kopvah says.
"The high amount of code reuse across UEFI BIOSes means that BIOS infection can be automatic and reliable.
"The point is less about how vendors don't fix the problems, and more how the vendors' fixes are going un-applied by users, corporations, and governments."
Though such "voodoo" hacking will likely remain a tool in the arsenal of intelligence and military agencies, it's getting easier, Kallenberg and Kovah believe. This is in part due to the widespread adoption of UEFI, a framework that makes it easier for the vendors along the manufacturing chain to add modules and tinker with the code. That's proven useful for the good guys, but also made it simpler for researchers to inspect the BIOS, find holes and create tools that find problems, allowing Kallenberg and Kovah to show off exploits across different PCs. In the demo to FORBES, an HP PC was used to carry out an attack on an ASUS machine. Kovah claimed that in tests across different PCs, he was able to find and exploit BIOS vulnerabilities across 80 per cent of machines he had access to and he could find flaws in the remaining 10 per cent.
"There are protections in place that are supposed to prevent you from flashing the BIOS and we've essentially automated a way to find vulnerabilities in this process to allow us to bypass them. It turns out bypassing the protections is pretty easy as well," added Kallenberg.
The NSA has a term for vulnerabilities it think are exclusive to it: NOBUS, for "nobody but us." Turns out that NOBUS is a flawed concept. As I keep saying: "Today's top-secret programs become tomorrow's PhD theses and the next day's hacker tools." By continuing to exploit these vulnerabilities rather than fixing them, the NSA is keeping us all vulnerable.
EDITED TO ADD (3/31): Slides from the CanSecWest presentation. The bottom line is that there are some pretty huge BIOS insecurities out there. We as a community and industry need to figure out how to regularly patch our BIOSes.
Posted on March 23, 2015 at 7:07 AM • 109 Comments