Ugreen DH2100+ USB Symlink Vulnerability

A critical vulnerability exists in Ugreen DH2100+ devices running versions through 5.3.0. This issue arises from inadequate handling of symbolic links by the USB handler component, allowing for symlink following. An attacker can exploit this vulnerability by creating symbolic links to arbitrary files on an external USB device and inserting them into the NAS device. This could lead to unauthorized access to, or modification of, files within the system via the Ugreen NAS client, thereby compromising confidentiality and integrity.

Impact

Exploitation of this vulnerability allows for unauthorized access to and modification of files within the system, through the Ugreen NAS client.

Reproduction

To reproduce this vulnerability, create a symbolic link on a USB device that points to an arbitrary file. Insert the USB device into the Ugreen DH2100+ NAS. The lax checks on symbolic links will allow access to or modification of the linked file through the NAS client.