CVE-2020-5355 in Isilon OneFS
Summary
by MITRE • 10/21/2022
The Dell Isilon OneFS versions 8.2.2 and earlier SSHD process improperly allows Transmission Control Protocol (TCP) and stream forwarding. This provides the remotesupport user and users with restricted shells more access than is intended.
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Analysis
by VulDB Data Team • 10/22/2022
The vulnerability identified as CVE-2020-5355 affects Dell Isilon OneFS storage systems running versions 8.2.2 and earlier, specifically targeting the SSHD (Secure Shell Daemon) process implementation. This security flaw represents a significant authorization and access control weakness that undermines the intended security boundaries within the system's remote support functionality. The issue manifests through improper handling of TCP and stream forwarding mechanisms within the SSH daemon, creating unintended access pathways that bypass normal security controls.
The technical implementation flaw resides in how the SSHD process manages network forwarding requests, particularly when handling transmission control protocol connections and stream forwarding operations. This misconfiguration allows users authenticated through the remotesupport account and other users with restricted shell access to establish connections that should be limited to specific network ports and forwarding types. The vulnerability essentially creates a privilege escalation vector where restricted users can access network resources beyond their intended operational scope, effectively widening their attack surface and access capabilities.
From an operational impact perspective, this vulnerability compromises the fundamental security model of the Isilon storage system by enabling unauthorized network access patterns. The remotesupport user account, which is typically intended for limited administrative support functions, gains expanded network capabilities that could allow attackers to pivot across network segments or access sensitive internal systems. This weakness particularly affects organizations relying on Isilon storage solutions for critical data infrastructure, as it undermines the network isolation principles that storage systems are designed to maintain.
The security implications extend beyond simple access control violations and align with multiple ATT&CK framework techniques including privilege escalation and lateral movement. Attackers could leverage this vulnerability to establish persistent network connections, conduct reconnaissance activities, or move laterally within the network environment. The vulnerability also relates to CWE-284 which addresses improper access control, and CWE-285 which covers improper authorization mechanisms within network services. Organizations utilizing affected Dell Isilon systems face increased risk of data exfiltration, unauthorized system access, and potential compromise of entire storage networks.
Mitigation strategies should focus on immediate patch application to upgrade to Dell Isilon OneFS versions that address this specific SSHD forwarding implementation issue. Network segmentation and firewall rules should be implemented to restrict SSH access to trusted administrative networks, while monitoring should be enhanced to detect unusual SSH forwarding activities. Regular security assessments of remote support configurations and privileged account management should be conducted to prevent exploitation of similar access control weaknesses. Organizations should also implement principle of least privilege controls for all remote support accounts and maintain strict audit trails of SSH session activities to detect potential misuse of the affected functionality.