Researcher creates proof-of-concept malware that infects BIOS, network cards

New Rakshasa hardware backdoor is persistent and hard to detect, researcher says

Security researcher Jonathan Brossard created a proof-of-concept hardware backdoor called Rakshasa that replaces a computer's BIOS (Basic Input Output System) and can compromise the operating system at boot time without leaving traces on the hard drive.

Brossard, who is CEO and security research engineer at French security company Toucan System, demonstrated how the malware works at the Defcon hacker conference on Saturday, after also presenting it at the Black Hat security conference on Thursday.

Rakshasa, named after a demon from the Hindu mythology, is not the first malware to target the BIOS -- the low-level motherboard firmware that initializes other hardware components. However, it differentiates itself from similar threats by using new tricks to achieve persistency and evade detection.

Rakshasa replaces the motherboard BIOS, but can also infect the PCI firmware of other peripheral devices like network cards or CD-ROMs, in order to achieve a high degree of redundancy.

Rakshasa was built with open source software. It replaces the vendor-supplied BIOS with a combination of Coreboot and SeaBIOS, alternatives that work on a variety of motherboards from different manufacturers, and also writes an open source network boot firmware called iPXE to the computer's network card.

All of these components have been modified so they don't display anything that could give their presence away during the booting process. Coreboot even supports custom splashscreens that can mimic the ones of the replaced BIOSes.

Existent computer architecture gives every peripheral device equal access to RAM (random access memory), Brossard said. "The CD-ROM drive can very well control the network card."

This means that even if someone were to restore the original BIOS, rogue firmware located on the network card or the CD-ROM could be used to reflash the rogue one, Brossard said.

The only way to get rid of the malware is to shut down the computer and manually reflash every peripheral, a method that is impractical for most users because it requires specialized equipment and advanced knowledge.

Brossard created Rakshasa to prove that hardware backdooring is practical and can be done somewhere in the supply chain, before a computer is delivered to the end user. He pointed out that most computers, including Macs, come from China.

However, if an attacker would gain system privileges on a computer through a different malware infection or an exploit, they could also theoretically flash the BIOS in order to deploy Rakshasa.

The remote attack method wouldn't work in all cases, because some PCI devices have a physical switch that needs to be moved in order to flash a new firmware and some BIOSes have digital signatures, Brossard said.

However, Coreboot has the ability to load a PCI extension firmware that takes precedence before the one written on the network card, therefore bypassing the physical switch problem.

The attack "totally works when you have physical access, but remotely it only works 99 percent of the time," Brossard said.

The iPXE firmware that runs on the network card is configured to load a bootkit -- malicious code that gets executed pior to the operating system and can infect it before any security products start.

Some known malware programs store the bootkit code inside the Master Boot Record (MBR) of the hard disk drive. This makes it easy for computer forensics specialists and antivirus products to find and remove.

Rakshasa is different because it uses the iPXE firmware to download the bootkit from a remote location and load it into RAM every time the computer boots.

"We never touch the file system," Brossard said. If you send the hard drive to a company and ask them to analyze it for malware they won't be able to find it, he said.

In addition, after the bootkit has done its job, which is to perform malicious modifications of the kernel -- the highest-privileged part of the operating system -- it can be unloaded from memory. This means that a live analysis of the computer's RAM won't be able to find it either.

Detecting this type of compromise is very hard because programs that run inside the operating system get their information from the kernel. The bootkit could very well fake this information, Brossard said.

The iPXE firmware is capable of communicating over Ethernet, Wi-Fi or Wimax and supports a variety of protocols including HTTP, HTTPS and FTP. This gives potential attackers a lot of options.

For example, Rakshasa can download the bootkit from a random blog as a file with a .pdf extension. It can also send the IP addresses and other network information of the infected computers to a predefined email address.

The attacker can push configuration updates or a new version of the malware over an encrypted HTTPS connection by communicating directly with the network card firmware and the command and control server can be rotated among different websites to make it harder for law enforcement or security researchers to take it down.

Brossard did not release Rakshasa publicly. However, since most of its components are open source, someone with sufficient knowledge and resources could replicate it. A research paper that explains the malware's implementation in more detail is available online.

Join the CSO newsletter!

Error: Please check your email address.
Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Lucian Constantin

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts