Cross posting this article posted by another user in the OS5 My Cloud subforum since it mentions a possible fix for a Zero Day RCE security vulnerability in OS3.
Another 0-Day Looms for Many Western Digital Users
At issue is a remote code execution flaw residing in all Western Digital network attached storage (NAS) devices running MyCloud OS 3 , an operating system the company only recently stopped supporting.
Researchers Radek Domanski and Pedro Ribeiro originally planned to present their findings at the Pwn2Own hacking competition in Tokyo last year. But just days before the event Western Digital released MyCloud OS 5 , which eliminated the bug they found. That update effectively nullified their chances at competing in Pwn2Own, which requires exploits to work against the latest firmware or software supported by the targeted device.
In recognition of this, the researchers have developed and released their own patch that fixes the vulnerabilities they found in OS 3 (the patch needs to be reapplied each time the device is rebooted). Western Digital said it is aware of third parties offering security patches for My Cloud OS 3.
“We have not evaluated any such patches and we are unable to provide any support for such patches,” the company stated.
NOTE: USE AT YOUR OWN RISK!!!
Note: Unknown if this applies to both v4.x and v2.x firmware or is for only for v2.x firmware. Script generates errors (for me) on first gen single bay My Cloud v4.x firmware. So use at your own risk!
One may be able to have this patch execute upon each My Cloud boot/reboot by putting the script “.sh” file into
/etc/rc2.d/S98user-start if it exists on one’s OS3 My Cloud firmware/root.
WD has indicated OS3 will no longer receive security updates.
We will not provide any further security updates to the My Cloud OS3 firmware. We strongly encourage moving to the My Cloud OS5 firmware. If your device is not eligible for upgrade to My Cloud OS 5, we recommend that you upgrade to one of our other My Cloud offerings that support My Cloud OS 5. More information can be found here: https://shop.westerndigital.com/support/software/my-cloud-os