A new Linux/IoT botnet named “Amnesia” has been targeting digital video recorders (DVRs) by exploiting an unpatched remote code execution vulnerability disclosed more than one year ago.
The threat, believed to be a variant of the Tsunami botnet, has been analyzed in detail by researchers at Palo Alto Networks. The botnet targets embedded systems, particularly DVRs made by China-based TVT Digital, which are sold under more than 70 brands worldwide.
The vulnerability exploited by the Amnesia malware was disclosed in March 2016 by researcher Rotem Kerner. The expert decided to make his findings public after the vendor ignored his attempts to report the flaw.
The security hole likely remains unpatched and an Internet scan conducted by Palo Alto Networks shows that there are roughly 227,000 vulnerable DVRs in the United States, Taiwan, India, Israel, Turkey, Malaysia and many other countries. A different search carried out via the Censys.io project revealed more than 700,000 IP addresses.
Amnesia has exploited the remote code execution flaw to identify vulnerable DVRs and take complete control of the devices.
Several IoT botnets emerged over the past months, including the notorious Mirai and Remaiten, which also includes capabilities borrowed from Tsunami.
What makes Amnesia interesting is the fact that it has virtual machine (VM) evasion capabilities – experts say this is the first Linux malware that attempts to evade sandboxes.
It’s not uncommon for Windows and Android malware to evade VMs, but such evasion techniques have not been seen in Linux malware.
“Amnesia tries to detect whether it’s running in a VirtualBox, VMware or QEMU based virtual machine, and if it detects those environments it will wipe the virtualized Linux system by deleting all the files in file system,” explained Palo Alto Networks researchers. “This affects not only Linux malware analysis sandboxes but also some QEMU based Linux servers on VPS or on public cloud.”
While Amnesia has yet to be used for large-scale attacks, experts believe it does have the potential to become a major botnet that can cause significant damage.
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