BadBIOS: has a researcher discovered an indestructible rootkit?
Mystery malware baffles everyone
A respected security researcher has reported finding an apparently new type of malware that infects all operating systems, resists even low-level attempts to remove it and can communicate with other infected PCs even when both systems are isolated from one another.
It sounds like a tale from a book on urban legends but security expert Dragos Ruiu has spent the last three years documenting the behaviour of a malware phenomenon he now calls ‘badBIOS’ but might be better described using the words ‘paranoia’ or ‘mind games’.
Exactly what it is designed to do he still doesn’t know and in truth his claims would be totally ignored as far-fetched nonsense if he weren’t also the founder of the prominent Pwn2Own hacking even as well as the organiser of CanSecWest.
Ruiu told Ars Technica that he first encountered badBIOS in 2010 when he noticed that a Mac OS X system refused to boot from a CD even after he’d installed a fresh copy of the OS; whatever had the system in its grip was able to control the BIOS configuration, undoing changes designed to counter its behaviour.
Bizarre to report but the same behaviour eventually spread to another of his systems running Open BSD Linux with the same configuration-changing symptoms. Whatever was carrying out these actions used IPv6 to transmit data regardless of whether that protocol was enabled on the system.
He further claims that infected systems could transmit small amounts of data to each other even when no interface cards (Ethernet, WiFi, Bluetooth) were installed.
"We had an air-gapped computer that just had its [firmware] BIOS reflashed, a fresh disk drive installed, and zero data on it, installed from a Windows system CD," Ruiu told Ars Technica.
"At one point, we were editing some of the components and our registry editor got disabled. It was like: wait a minute, how can that happen? How can the machine react and attack the software that we're using to attack it? This is an air-gapped machine and all of a sudden the search function in the registry editor stopped working when we were using it to search for their keys," said Ruiu.
After years of fruitless research, he had decided to publicise the issue he believes suggests that the malware has found a foolproof way to infect and control any computer’s BIOS (specifically UEFI) chip in ways that make it impossible to detect directly let alone remove.
As to how badBIOS-infected systems communicate, Ruiu has proposed the almost incredible theory that it must be using ultrasonic audio communications, that is by sending signals via a PC speaker of the transmitting system and the microphone of the receiving system.
A number of elements of the story remain unexplained, starting with the fact that nobody else has reported encountering the malware or any of its symptoms. It has also been suggested that Ruiu should make available BIOS images available for peer inspection.
"The suspicion right now is there's some kind of buffer overflow in the way the BIOS is reading the drive itself, and they're reprogramming the flash controller to overflow the BIOS and then adding a section to the BIOS table," he told Ars Technica.
Ruiu’s research has been hampered by the malware’s ability to infect and stay resident on systems, making it impossible to be certain test these machines were completely clean.
“I'm down to a precious few reference systems that are clean. I lost another one yesterday confirming that's simply plugging in a USB device from an infected system into a clean one is sufficient to infect,” he wrote on 23 October on his Google+ blog.
If bad BIOS does turn out to be new form of super-rootkit, there could be two explanations for its existence. A long shot is that it is a proof-of-concept rootkit that accidentally escaped from a researcher’s clutches (see below). More probably given its age and the fact that badBIOS looks like the infector component of a larger programme, it is a fragment of a previously unknown state cyberweapon (a tell-tale sign if this is that it spreads via USB stick which means it is targeting isolated computers).
It is pure speculation but badBIOS just looks too strange and over-engineered for commercial malware. It’s also not clear what the command and control might be for such a programme; at that point most criminal malware becomes far easier to detect and block.
Ruiu's discovery is not without precedent. In 2012, fellow researcher Jonathan Brossard demonstrated a BIOS-level infector that could attack the firmware of different types of controller (i.e. CD-ROM and NIC) inside a PC, making itself extremely hard to detect and remove.