CVE-2016-4923 in Junos
Summary
by MITRE
Insufficient cross site scripting protection in J-Web component in Juniper Networks Junos OS may potentially allow a remote unauthenticated user to inject web script or HTML and steal sensitive data and credentials from a J-Web session and to perform administrative actions on the Junos device. Juniper SIRT is not aware of any malicious exploitation of this vulnerability. Affected releases are Juniper Networks Junos OS 11.4 prior to 11.4R13-S3; 12.1X44 prior to 12.1X44-D60; 12.1X46 prior to 12.1X46-D40; 12.1X47 prior to 12.1X47-D30; 12.3 prior to 12.3R11; 12.3X48 prior to 12.3X48-D20; 13.2X51 prior to 13.2X51-D39, 13.2X51-D40; 13.3 prior to 13.3R9; 14.1 prior to 14.1R6; 14.2 prior to 14.2R6; 15.1 prior to 15.1R3; 15.1X49 prior to 15.1X49-D20; 15.1X53 prior to 15.1X53-D57.
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Analysis
by VulDB Data Team • 01/03/2023
The vulnerability identified as CVE-2016-4923 represents a critical cross-site scripting weakness within the J-Web component of Juniper Networks Junos OS, exposing devices to significant remote attack vectors. This flaw resides in the web-based management interface that administrators use to configure and monitor network devices, creating a pathway for malicious actors to exploit the system without requiring authentication credentials. The vulnerability specifically affects multiple versions of Junos OS across various release branches, spanning from version 11.4 through 15.1X53, with each affected branch requiring specific patch levels to achieve remediation. The exposure occurs through insufficient input validation and output encoding mechanisms within the J-Web framework, which fails to properly sanitize user-supplied data before rendering it in web responses.
The technical nature of this vulnerability aligns with CWE-79, which categorizes cross-site scripting flaws as weaknesses in web applications where untrusted data is improperly handled during web page generation. Attackers can leverage this weakness by crafting malicious payloads that get executed within the context of an authenticated user's browser session, potentially compromising the integrity of sensitive information and administrative functions. The J-Web interface, designed to provide web-based access to Junos device management capabilities, becomes a vector for script injection attacks that can result in session hijacking, credential theft, and unauthorized administrative actions. This vulnerability operates at the application layer, specifically targeting the web server component that handles user interactions and device configuration requests.
The operational impact of CVE-2016-4923 extends beyond simple data theft, as it enables attackers to perform administrative actions on the affected Junos devices without proper authorization. This capability fundamentally compromises the security posture of network infrastructure, potentially allowing threat actors to modify device configurations, disable security features, or establish persistent access points within the network. The remote unauthenticated nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, making it particularly dangerous for devices that are exposed to external traffic. The potential for credential theft through session manipulation creates additional risk for organizations that rely on web-based management interfaces for device administration, as compromised sessions can lead to complete network compromise.
Mitigation strategies for this vulnerability require immediate deployment of Juniper's official security patches corresponding to the affected release versions, with particular attention to the specific patch levels mentioned in the advisory. Organizations should implement network segmentation to reduce exposure of Junos devices to untrusted networks and consider disabling J-Web functionality where possible, particularly on devices that do not require web-based management access. The remediation process should include comprehensive testing of patches in controlled environments before deployment to production systems, ensuring that the security updates do not introduce compatibility issues with existing network operations. Additionally, organizations should conduct thorough vulnerability assessments to identify any potential exploitation attempts that may have occurred prior to patch deployment, and implement monitoring procedures to detect unusual activity in web-based management interfaces. This vulnerability demonstrates the importance of maintaining up-to-date security patches and the critical role that web-based management interfaces play in overall network security architecture.