A team of researchers claim they can make SSDs impervious to ransomware attacks by detecting infections and reverting unexpected encryption within a matter of seconds, at the cost of a small increase in latency.
The group includes engineers from South Korea’s Inha University, Daegu Institute of Science and Technology, and the Cyber Security Department at Ewha Womans University (EWU) as well as a researcher from the University of Central Florida in the US.
"I came up with the idea of firmware level detection because I know that many [users] don't install anti-ransomware software," DaeHun Nyang, PhD, at EWU told The Register of the origin of the team's research project. "So I thought that it would be good if we can protect people not having anti-ransomware installed on their computers by providing them with an anti-ransomware-intrinsic SSD.
"Fortunately, my colleague Sungjin [Lee] was working on NAND flash, and he knew it would be easy to recover the data considering NAND flash's delayed deletion."
The core concept of SSD-Insider++ is relatively simple: look for patterns of drive activity corresponding to ransomware attacks, where files are encrypted and the required decryption key ransomed off, and stop them in their tracks. Rather than doing so in software, however, it does it directly on the storage device itself - by running on the controller hardware.
"When ransomware activity is detected by SSD-Insider++, input/output to the storage is suspended," Nyang explained. "During the suspension, users can remove the ransomware process."
In some ways, SSD-Insider++ is akin to the "antivirus" floppy drives of the Commodore Amiga era. Where a physical switch was once used to prevent unexpected writes to a floppy disk's boot sector, SSD-Insider++ relies on clever analysis to spot unwanted patterns, and then locks the drive, warning the user through a companion application that they've been infected.
We note that Cignet, for one, offers anti-ransomware SSDs though its solution seems tied to or is reliant on Windows.
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Crucially, SSD-Insider++ isn't just about detecting ransomware: its creators claim it can also reverse any resulting damage to data in a matter of seconds. "SSD-Insider++ does not create any copies of data," the team wrote in the paper.
"Instead, it leverages the operational characteristics of an SSD that keeps old versions of data to hide the out-of-place update nature of NAND flash. This enables us to back up original files without any extra copies and to instantly roll back infected files if necessary."
The result, according to testing on in-the-wild and lab-grade malware samples, is a system which is capable of detecting 100 per cent of tested ransomware attacks and reversing the damage within 10 seconds of encryption beginning - and at the relatively minor cost of a 12.8 per cent to 17.3 per cent increase in latency and a worst-case throughput drop measured at around 8 per cent.
"We have evaluated SSD-Insider++ using real-world and in-house ransomware programs, including WannaCry and Mole, while various background applications are running," the team wrote. "Our implementation of SSD-Insider++ has 100 per cent detection accuracy with almost 0 per cent FRR/FAR [False Rejection Rate and False Acceptance Rate] in most cases with shorter than 10 seconds of detection latency.
"We also have confirmed that SSD-Insider++ recovers encrypted files within one second without any data loss.
"Our evaluation results showed that SSD-Insider++ was accurate and fast for detection, and it could perfectly recover an infected SSD without any data loss."
A major selling point of the technology is that it exists purely in firmware, meaning it could potentially be added to existing SSDs without the need for any hardware modifications. "I believe that the key feature of SSD-Insider++ can be implemented without additional resources," Sungjin Lee, PhD, at Daegu Institute of Science and Technology told The Register.
"To implement some advanced features like entropy-based detection, however, extra hardware resources - e.g., higher performance Arm CPU or hardware accelerators - would be needed. These days SSDs are evolving to embrace more powerful hardware resources - e.g., Cortex-A Arm CPU, NPU [Neural Processing Unit], FPGA, and encryption/decryption engines - and thus I expect that such a hardware requirement wouldn't be a serious obstacle for a wide adoption of SSD-Insider++."
The theoretical ability to bring ransomware protection to existing SSDs at a relatively low performance cost doesn't have companies beating down the researchers' doors, however. "We have approached several companies here in Korea, but not yet found any company to apply this technology," Nyang told us of the team's efforts to bring SSD-Insider++ to the masses.
They are very conservative in adopting new technology especially if it may lead to even slight performance degradation, but we are interested in commercialising this system and [are] still working on it
"They are very conservative in adopting new technology especially if it may lead to even slight performance degradation, [but] we are interested in commercialising this system and [are] still working [on it]."
While focused on solid-state storage, there's the potential to expand the concept to certain other storage devices too. "SSD-Insider++ cannot be used for conventional HDDs where user data is updated in-place. For recent HDDs - e.g., SMR [Shingled Magnetic Recording] drives - based on append-only magnetic media, the same idea of SSD-Insider++ can be directly applied," Lee told us.
"In addition, compared to SSDs, HDDs employ low-end CPUs and thus SSD-Inside++ may cause non-negligible overheads - but a powerful computing unit might be unnecessary, considering [the] low throughput and long latency of HDDs."
"Unfortunately, this new feature may not be foolproof," Jake Moore, security expert at ESET UK, told The Register in a statement designed to temper expectations. "The function leverages a delay in deletion which means that ransomware developers would and could still bypass this feature with the knowledge of how this antidote operates.
"With this level of commitment into protection, a standard backup process would still be efficient and is what the majority of companies already adhere to. It is, however, the start of better processes in the battle against the 21st century nemesis which still causes havoc around the world on a daily basis."
The paper on SSD-Insider++, SSD-Assisted Ransomware Detection and Data Recovery Techniques, has been published in the journal IEEE Transactions on Computers under closed-access terms. ®