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Another Exploit Hits WD My Book Live Owners

A hard drive, disassembled
(Image credit: Photo by Ivo Brasil from Pexels)

While it will come as no comfort to those who had their Western Digital My Book Live NAS drives wiped last week, it seems they were attacked by a combination of two exploits, and possibly caught in the fallout of a rivalry between two different teams of hackers. 

My Book Live packaging

(Image credit: Western Digital)

Initially, after the news broke on Friday, it was thought a known exploit from 2018 was to blame, allowing attackers to gain root access to the devices. However, it now seems that a previously unknown exploit was also triggered, allowing hackers to remotely perform a factory reset without a password and to install a malicious binary file.

A statement from Western Digital, updated today, reads: “My Book Live and My Book Live Duo devices are under attack by exploitation of multiple vulnerabilities present in the device ... The My Book Live firmware is vulnerable to a remotely exploitable command injection vulnerability when the device has remote access enabled. This vulnerability may be exploited to run arbitrary commands with root privileges. Additionally, the My Book Live is vulnerable to an unauthenticated factory reset operation which allows an attacker to factory reset the device without authentication. The unauthenticated factory reset vulnerability [has] been assigned CVE-2021-35941.”

Analysis of WD’s firmware suggests code meant to prevent the issue had been commented out, preventing it from running, by WD itself, and an authentication type was not added to component_config.php which results in the drives not asking for authentication before performing the factory reset. 

The question then arises of why one hacker would use two different exploits, particularly an undocumented authentication bypass when they already had root access through the command injection vulnerability, with venerable tech site Ars Technica speculating that more than one group could be at work here, with one bunch of bad guys trying to take over, or sabotage, another’s botnet. 

Western Digital has responded admirably, offering data recovery services beginning in July, and a trade-in program to switch the obsolete My Book Live drives for more modern My Cloud devices. 

If you own one of the affected devices, do not connect it to the Internet and contact Western Digital for support.