Network-attached storage (NAS) devices are riddled with vulnerabilities that can put the security of sensitive data and networks at risk, a researcher has found. To prove his point, he has created a proof-of-concept worm that can infect devices from three different manufacturers.
Earlier this year, Jacob Holcomb, a security analyst at Baltimore-based firm Independent Security Evaluators, started researching the security of NAS devices. He selected popular devices from 10 manufacturers and found that they were all were susceptible to root compromise. In addition, he found that exploiting half of them did not require authentication.
The tested devices were: Asustor AS-602T, TRENDnet TN-200 and TN-200T1, QNAP TS-870, Seagate BlackArmor 1BW5A3-570, Netgear ReadyNAS104, D-LINK DNS-345, Lenovo IX4-300D, Buffalo TeraStation 5600, Western Digital MyCloud EX4 and ZyXEL NSA325 v2.
During a presentation last week at the Black Hat Europe security conference in Amsterdam, Holcomb demonstrated a proof-of-concept worm that can automatically infect the D-LINK DNS-345, TRENDnet TN-200/TN-200T1 and Western Digital MyCloud EX4 devices by exploiting command injection and authentication bypass vulnerabilities, which as far as he knows, are still unpatched.
Holcomb's worm can scan predefined ranges of IP (Internet Protocol) addresses to find devices that respond over TCP port 80 and match certain digital fingerprints associated with the targeted NAS devices. Once it identifies a vulnerable device, the worm launches the necessary exploit to obtain root access and installs an interactive shell. It then downloads and runs a binary copy of itself and begins scanning from the new device.
Holcomb has not released the worm's code publicly, but plans to do so in the future after the affected vendors patch the vulnerabilities and users have a chance to upgrade. His demonstration was intended to show that creating self-propagating malware for NAS devices is relatively easy, because many of these systems share the same architecture and even code that was provided by chipset vendors.
Furthermore, some manufacturers reuse code across entire product lines, so one vulnerability found in a low-end consumer NAS device can also be present in expensive, enterprise-grade devices from the same manufacturer, according to Holcomb. When it comes to NAS devices, paying more does not necessarily mean better security, he said.
While Holcomb's proof-of-concept worm did nothing more than propagate within a local area network, attackers could create similar malware to compromise NAS devices that are accessible from the Internet and use them for performing distributed denial-of-service (DDoS) attacks and other malicious activities.
These are quite powerful devices with a lot of storage capacity, so they present many opportunities for abuse, Holcomb said.
Cases of large-scale exploitation of NAS devices have already been seen in the wild. Researchers from Dell SecureWorks reported in June that a hacker made over US$600,000 after hacking into Synology NAS devices and using them to mine Dogecoin, a type of cryptocurrency.
In August, some Synology NAS device owners reported that their systems had been infected by a malware program called SynoLocker that encrypted their personal files and held them to ransom.
A compromised NAS device could also serve as a pivot point inside the local network to attack other systems, so they wouldn't necessarily have to be compromised from the Internet. Attackers could create Windows malware that scans the local network for vulnerable NAS devices and infects them.
Such compromises would be hard to detect because there are no antivirus or security products running on NAS devices. The compromises would allow attackers to maintain a foothold in the network even if the original Windows malware is later removed.
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