CVE-2020-5355 is a medium-severity vulnerability identified in Dell Isilon OneFS versions 8.2.2 and earlier. The vulnerability arises from incorrect default permissions in the SSHD process, specifically related to Transmission Control Protocol (TCP) and stream forwarding capabilities. The issue allows the 'remotesupport' user and other users with restricted shells to gain more access than intended by improperly permitting TCP and stream forwarding. This is categorized under CWE-276, which refers to incorrect default permissions that can lead to unauthorized access or privilege escalation. The vulnerability does not require user interaction and can be exploited remotely with low attack complexity, but it does require privileges equivalent to the 'remotesupport' user or restricted shell users, indicating some level of prior access or authentication is necessary. The impact primarily affects confidentiality, as unauthorized users could potentially forward network traffic or access resources beyond their intended scope. There is no indication of impact on integrity or availability. No known exploits are reported in the wild, and no patches are explicitly linked in the provided information, though Dell likely has addressed this in later versions. The vulnerability affects networked storage systems running OneFS, which are commonly used in enterprise environments for scalable storage solutions.

For European organizations, the impact of this vulnerability could be significant, especially for those relying on Dell Isilon OneFS for critical data storage and management. Unauthorized TCP and stream forwarding could allow attackers or unauthorized users to bypass network segmentation or access sensitive data streams, potentially leading to data leakage or exposure of confidential information. This risk is heightened in sectors with strict data protection regulations such as GDPR, where unauthorized data access can lead to severe legal and financial penalties. Additionally, organizations in finance, healthcare, and government sectors that use Isilon storage solutions might face increased risk due to the sensitivity of the stored data. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach potential alone warrants attention. The requirement for some level of authentication limits the risk to insider threats or attackers who have already gained limited access, but the improper permissions could facilitate lateral movement or privilege escalation within the network.

European organizations should first verify their Dell Isilon OneFS version and upgrade to the latest available version where this vulnerability is addressed. If immediate upgrading is not feasible, organizations should restrict access to the 'remotesupport' user and any accounts with restricted shells, ensuring they are tightly controlled and monitored. Network segmentation should be enforced to limit the ability of these users to forward TCP streams to sensitive network segments. Implement strict SSH configuration policies that disable TCP and stream forwarding for non-administrative users. Regular auditing of user permissions and SSH session activities can help detect misuse. Additionally, employing network-level controls such as firewall rules to restrict unauthorized forwarding and monitoring network traffic for unusual forwarding patterns can reduce exploitation risk. Finally, organizations should maintain robust incident response plans to quickly address any detected misuse related to this vulnerability.