#VU51481 Link following in Western Digital products - CVE-2021-3310

Vulnerability identifier: #VU51481

Vulnerability risk: High

CVSSv4.0: 8.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber]

CVE-ID: CVE-2021-3310

CWE-ID: CWE-59

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
My Cloud EX2 Ultra
Hardware solutions / Other hardware appliances
My Cloud Mirror Gen 2
Hardware solutions / Other hardware appliances
My Cloud EX4100
Hardware solutions / Other hardware appliances
My Cloud PR2100
Hardware solutions / Other hardware appliances
My Cloud PR4100
Hardware solutions / Other hardware appliances
My Cloud DL2100
Hardware solutions / Other hardware appliances
My Cloud DL4100
Hardware solutions / Other hardware appliances
My Cloud EX2100
Hardware solutions / Other hardware appliances
My Cloud (P/N: WDBCTLxxxxxx-10)
Hardware solutions / Other hardware appliances

Vendor: Western Digital

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to the affected software mishandle Symbolic Link Following within the SMB and AFP services. A remote attacker can create a symlink to read arbitrary files and gain access to sensitive information or execute arbitrary code on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

My Cloud EX2 Ultra: before 5.10.122

My Cloud Mirror Gen 2: before 5.10.122

My Cloud EX4100: before 5.10.122

My Cloud PR2100: before 5.10.122

My Cloud PR4100: before 5.10.122

My Cloud DL2100: before 5.10.122

My Cloud DL4100: before 5.10.122

My Cloud EX2100: before 5.10.122

My Cloud (P/N: WDBCTLxxxxxx-10): before 5.10.122

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External links
https://www.westerndigital.com/support/productsecurity/wdc-21002-my-cloud-firmware-version-5-10-122
https://www.zerodayinitiative.com/advisories/ZDI-21-277/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.