IoT devices tend to be simple. So simple, in fact, that turning them off and back on again has historically been a reliable way to eliminate malware. Now, though, a new variant of the Hide and Seek bot can remain persistent on IoT devices that use a variety of different hardware and Linux platforms.
A research team at Bitdefender described the new variant of a botnet they had first discovered in January with notes of two important developments, one novel and one in keeping with a broader trend in malware.
Persistence in IoT devices is novel and disturbing since it removes a common defense mechanism from the security team's toolbox. In order to achieve persistence, Hide and Seek must gain access to the device via Telnet, using the protocol to achieve root access to the device. With root access, a file is placed in the /etc/init.d/ directory where it executes each time the device is rebooted. According to the Bitdefender researchers, there are at least 10 different versions of the executables that can run on 10 different system variants.
"Once this new botnet has been armed, it isn’t going to do anything but increase the availability of the already prevalent DDoS tools for those looking to launch such attacks," says Sean Newman, director of product management at Corero Network Security. He points out that this is disturbing for technology advancement reasons, but it might not immediately make a huge impact on the DDoS environment. "With most IoT devices rarely rebooted and easily re-infected if they are, it feels like this may not make as much impact as you might think to the already burgeoning supply of botnets," he says, "particularly those being used to launch damaging DDoS attacks."
As part of a broader trend in malware, Hide and Seek shows considerable development and evolution in the code being deployed. Since its initial discovery in January of this year, "The botnet seems to undergo massive development as new samples compiled for a variety of architectures have been added as payloads," according to the Bitdefender Labs blog post on the malware.
"This showcases the continued evolution of malware and how the internet continues to democratize access to information, malicious or otherwise," says Dan Mathews, director at Lastline. He lists some of the ways in which the industry has seen botnet malware evolve since the days of Mirai, including, "…default & expanded password guessing and cross-compiled code to run on multiple CPU architectures added, as well as exploits added to leverage IoT vulnerabilities, exploits added for peer to peer communications, and now exploits added for persistence."
Hide and Seek's original version was notable for using a proprietary peer-to-peer network for both C&C and new infection communication. Now that persistence has been added to the feature mix, the botnet has become a more pressing concern for the owners of the 32,000+ already infected and those IoT devices that are vulnerable and still unprotected.