CVE-2019-5426 in Networks EdgeSwitch
Summary
by MITRE
In Ubiquiti Networks EdgeSwitch X v1.1.0 and prior, an unauthenticated user can use the "local port forwarding" and "dynamic port forwarding" (SOCKS proxy) functionalities. Remote attackers without credentials can exploit this bug to access local services or forward traffic through the device if SSH is enabled in the system settings.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/29/2020
The vulnerability identified as CVE-2019-5426 affects Ubiquiti Networks EdgeSwitch X series switches running firmware versions v1.1.0 and earlier. This security flaw represents a critical authorization bypass issue that allows unauthenticated remote attackers to leverage built-in networking functionalities for malicious purposes. The vulnerability specifically impacts the switch's SSH service configuration, where unauthorized users can exploit two distinct forwarding mechanisms to gain access to internal network resources.
The technical implementation of this vulnerability stems from improper access controls within the EdgeSwitch X device's SSH daemon implementation. The device exposes both local port forwarding and dynamic port forwarding capabilities through its SOCKS proxy functionality without requiring authentication. This design flaw creates a pathway for attackers to tunnel network traffic through the switch device, effectively using it as a pivot point to access internal services that would normally be restricted from external access. The vulnerability exists because the SSH service fails to properly validate user credentials before granting access to these forwarding mechanisms, which are typically intended for legitimate administrative use only.
From an operational perspective, this vulnerability presents significant risks to network security infrastructure. Attackers can exploit the unauthenticated access to perform reconnaissance activities by scanning internal network services, conduct man-in-the-middle attacks, or establish persistent access points within the network. The impact extends beyond simple information disclosure as it allows attackers to potentially move laterally through the network, accessing sensitive systems that are typically protected by network segmentation. The vulnerability is particularly dangerous because it requires no prior authentication credentials, making it an attractive target for automated exploitation tools and opportunistic attackers who may be scanning for vulnerable network equipment.
The attack surface of this vulnerability aligns with several ATT&CK framework techniques including T1046 Network Service Scanning and T1071 Application Layer Protocol. The vulnerability also corresponds to CWE-284 Improper Access Control, which specifically addresses insufficient access control mechanisms that allow unauthorized users to access system resources. Organizations using Ubiquiti EdgeSwitch X devices should immediately implement mitigations including disabling SSH access when not required, implementing network segmentation to isolate critical systems, and applying firmware updates to versions that address this authorization bypass. Network monitoring should be enhanced to detect unusual SSH traffic patterns that may indicate exploitation attempts, while access controls should be reviewed to ensure that only authorized personnel can establish connections to the switch devices.