Western Digital addressed a critical bug in My Cloud OS 5

Western Digital fixed a critical flaw affecting My Cloud OS 5 devices that allowed attackers to gain remote code execution with root privileges.

Western Digital has addressed a critical vulnerability, tracked as CVE-2021-44142, that could have allowed attackers to gain remote code execution with root privileges on unpatched My Cloud OS 5 devices.

The CVE-2021-44142 flaw affects the following devices:

My Cloud PR2100
My Cloud PR4100
My Cloud EX4100
My Cloud EX2 Ultra
My Cloud Mirror Gen 2
My Cloud DL2100
My Cloud DL4100
My Cloud EX2100
My Cloud
WD Cloud

The CVE-2021-44142 vulnerability is a Samba out-of-bounds heap read/write that impacts the vfs_fruit VFS module when parsing EA metadata when opening files in smbd.

This VFS module is part of the samba suite and provides enhanced compatibility with Apple SMB clients and interoperability with a Netatalk 3 AFP fileserver.

“The specific flaw exists within the parsing of EA metadata when opening files in smbd. Access as a user that has write access to a file’s extended attributes is required to exploit this vulnerability. Note that this could be a guest or unauthenticated user if such users are allowed write access to file extended attributes.” reads the security advisory for this flaw. “The problem in vfs_fruit exists in the default configuration of the fruit VFS module using fruit:metadata=netatalk or fruit:resource=file. If both options are set to different settings than the default values, the system is not affected by the security issue.”

The flaw affects all versions of Samba prior to 4.13.17, an attacker can trigger this vulnerability without user interaction. The vulnerability was reported by the security researcher Orange Tsai from DEVCORE.

“This specific flaw exists within the parsing of extended attributes (EA) metadata when opening a file in smbd. This vulnerability can be exploited by unauthenticated users if they are allowed write access to file extended attributes.” reads the advisory published by Western Digital. “This vulnerability was addressed by removing the “fruit” VFS module from the list of configured VFS objects and by changing EA support configurations.”

The vulnerability was reported by Nguyen Hoang Thach (@hi_im_d4rkn3ss) and Billy Jheng Bing-Jhong (@st424204) working with Trend Micro’s Zero Day Initiative.

Western Digital fixed the issue by removing the “fruit” VFS module from the list of configured VFS objects and changing EA support configurations. The company addressed the flaw with the release of My Cloud OS 5 Firmware 5.21.104 on March 23, 2022.

Western Digital also addressed another critical vulnerability in the open-source Netatalk Apple File Protocol fileserver.

Follow me on Twitter: @securityaffairs and Facebook

[adrotate banner=”9″]

[adrotate banner=”12″]

Pierluigi Paganini

(SecurityAffairs – hacking, BazarLoader)

[adrotate banner=”5″]

[adrotate banner=”13″]

Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.