CVE-2016-4927 in Junos Space
Summary
by MITRE
Insufficient validation of SSH keys in Junos Space before 15.2R2 allows man-in-the-middle (MITM) type of attacks while a Space device is communicating with managed devices.
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Analysis
by VulDB Data Team • 09/10/2020
The vulnerability identified as CVE-2016-4927 represents a critical security flaw in Junos Space software versions prior to 15.2R2, specifically targeting the Secure Shell protocol implementation within the network management platform. This weakness stems from inadequate validation mechanisms for SSH host keys during device communication sessions, creating a significant attack surface that adversaries can exploit to compromise network integrity. The vulnerability exists within the authentication and key exchange processes that govern how Junos Space devices establish secure connections with managed network equipment, fundamentally undermining the cryptographic assurances that should protect these communications.
The technical root cause of this vulnerability lies in the insufficient cryptographic validation of SSH host keys, which allows attackers to perform man-in-the-middle attacks by presenting forged host keys to the Junos Space management system. When a managed device attempts to establish an SSH connection with the Junos Space platform, the system fails to properly verify the authenticity of the presented host key against known good key fingerprints or certificate authorities. This validation failure enables attackers to intercept and potentially manipulate communications between the management platform and network devices, as the system accepts any host key without proper cryptographic verification. The flaw specifically impacts the SSH key exchange mechanism, where the lack of robust key validation creates a pathway for attackers to establish unauthorized communication channels.
The operational impact of this vulnerability extends beyond simple network monitoring concerns, as it fundamentally compromises the security posture of organizations relying on Junos Space for network device management. Attackers exploiting this vulnerability can gain unauthorized access to network management functions, potentially leading to complete network compromise through privilege escalation or unauthorized configuration changes. The vulnerability affects the integrity of network device communications, allowing attackers to eavesdrop on management sessions, inject malicious commands, or redirect traffic through compromised network paths. Organizations using Junos Space for managing large network infrastructures face significant risk of unauthorized access to critical network components, as the vulnerability undermines the trust model that should exist between management systems and managed devices.
Mitigation strategies for CVE-2016-4927 primarily focus on immediate software updates and enhanced security configurations. Organizations must upgrade their Junos Space installations to version 15.2R2 or later, which contains the necessary cryptographic validation fixes. Additionally, implementing SSH key management best practices including explicit host key verification, maintaining updated key fingerprints, and employing certificate-based authentication mechanisms can significantly reduce exposure. Network segmentation and monitoring solutions should be deployed to detect anomalous SSH connection patterns or unauthorized key exchanges. The vulnerability aligns with CWE-310, which addresses cryptographic weakness in key validation processes, and maps to ATT&CK techniques involving credential access through network sniffing and man-in-the-middle attacks. Organizations should also consider implementing additional security controls such as network access controls, intrusion detection systems, and regular security audits to complement the software patches and maintain overall security hygiene.