Advisory Details

December 16th, 2020

(Pwn2Own) Western Digital MyCloud PR4100 nasAdmin Incorrect Authorization Authentication Bypass Vulnerability

ZDI-20-1448
ZDI-CAN-12385

CVE ID CVE-2020-28970
CVSS SCORE 0.0, (AV:P/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:N)
AFFECTED VENDORS Western Digital
AFFECTED PRODUCTS MyCloud PR4100
VULNERABILITY DETAILS

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of Western Digital MyCloud PR4100. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the nasAdmin service, which listens on TCP port 80 and 443 by default. The issue results from incorrect string matching logic when accessing protected pages. An attacker can leverage this vulnerability to execute arbitrary code in the context of root.

ADDITIONAL DETAILS Western Digital has issued an update to correct this vulnerability. More details can be found at:
https://www.westerndigital.com/support/productsecurity/wdc-20009-os5-firmware-5-06-115
DISCLOSURE TIMELINE
  • 2020-11-06 - Vulnerability reported to vendor
  • 2020-12-16 - Coordinated public release of advisory
CREDIT Sam Thomas (@_s_n_t) of Pentest Ltd (@pentestltd)
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