CVE-2017-2335 in ScreenOS
Summary
by MITRE
A persistent cross site scripting vulnerability in NetScreen WebUI of Juniper Networks Juniper NetScreen Firewall+VPN running ScreenOS allows a user with the 'security' role to inject HTML/JavaScript content into the management session of other users including the administrator. This enables the lower-privileged user to effectively execute commands with the permissions of an administrator. This issue affects Juniper Networks ScreenOS 6.3.0 releases prior to 6.3.0r24 on SSG Series. No other Juniper Networks products or platforms are affected by this issue.
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Analysis
by VulDB Data Team • 01/01/2021
This vulnerability represents a critical persistent cross site scripting flaw in the NetScreen WebUI component of Juniper Networks Juniper NetScreen Firewall+VPN devices running ScreenOS versions prior to 6.3.0r24 on SSG Series platforms. The vulnerability stems from inadequate input validation and output encoding mechanisms within the web management interface, allowing malicious users with the 'security' role to inject malicious HTML and JavaScript content into the management session of other users. The technical implementation of this flaw demonstrates a failure in proper sanitization of user-supplied data within the web application layer, creating a persistent XSS attack vector that can be exploited across multiple user sessions.
The operational impact of this vulnerability is severe as it enables privilege escalation from a 'security' role user to administrative privileges, effectively allowing a lower-privileged attacker to execute commands with full administrator permissions. This represents a direct violation of the principle of least privilege and demonstrates a critical flaw in the role-based access control implementation within the ScreenOS management interface. The persistent nature of the vulnerability means that injected malicious content can affect multiple users over time, making it particularly dangerous for environments where multiple administrators or security personnel access the same management interface. According to CWE classification, this vulnerability maps to CWE-79 - Improper Neutralization of Input During Web Page Generation, and more specifically to CWE-80 - Improper Neutralization of Script-Related HTML Tags in a Web Page, with additional implications for CWE-20 - Improper Input Validation.
The attack surface for this vulnerability is limited to specific Juniper ScreenOS versions running on SSG Series devices, but the impact remains significant for organizations relying on these platforms for network security management. Attackers exploiting this vulnerability can potentially gain complete control over the firewall configuration, modify security policies, access sensitive network information, and perform unauthorized network operations. The vulnerability creates a persistent backdoor within the management interface that can be leveraged for ongoing attacks against the network infrastructure. From an ATT&CK framework perspective, this vulnerability aligns with T1078 - Valid Accounts and T1566 - Phishing, as it enables attackers to escalate privileges and maintain persistent access through compromised management sessions, while also supporting T1059 - Command and Scripting Interpreter through the execution of injected JavaScript code with administrative privileges.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to ScreenOS 6.3.0r24 or later versions, applying the relevant security patches provided by Juniper Networks, and implementing additional monitoring of management sessions for suspicious activity. Network segmentation and restricted access controls for management interfaces should be enforced to limit the attack surface, while regular security audits of web application components should be conducted to identify similar input validation issues. The vulnerability highlights the importance of proper web application security testing and the need for robust input sanitization mechanisms in management interfaces, particularly those handling privileged user sessions and administrative functions.