CVE-2017-2338 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 systems running ScreenOS version 6.3.0 prior to 6.3.0r24 on SSG Series devices. The flaw operates as a server-side persistent XSS vulnerability that allows attackers with the specific 'security' role to inject malicious HTML and JavaScript content into the management interface. This particular vulnerability is classified under CWE-79 as Cross-Site Scripting and aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter. The attack vector leverages the web-based management interface where the injected scripts persist and execute in the context of other users' sessions, including high-privilege administrator accounts.
The technical implementation of this vulnerability exploits the insufficient input validation and output encoding mechanisms within the ScreenOS web management interface. When a user with 'security' privileges submits malicious content through the web interface, the system fails to properly sanitize the input before rendering it in subsequent user sessions. This creates a persistent XSS condition where the malicious code executes whenever other users, particularly administrators, view the affected pages. The vulnerability specifically targets the management session context, allowing the lower-privileged attacker to effectively escalate privileges and execute commands with administrator-level permissions. The attack requires minimal privileges since the 'security' role already grants access to the web management interface, making this a particularly dangerous privilege escalation vector.
The operational impact of this vulnerability extends beyond simple session hijacking, as it enables full administrative control over affected systems. An attacker with the 'security' role can inject persistent scripts that execute in administrator sessions, potentially leading to complete system compromise, data exfiltration, and unauthorized configuration changes. This vulnerability undermines the principle of least privilege and creates a significant risk for organizations relying on Juniper NetScreen devices for network security. The persistence of the XSS payload means that even after the initial injection, the malicious code continues to execute in subsequent user sessions without requiring repeated exploitation attempts. This makes the vulnerability particularly dangerous for long-running management sessions and persistent threat scenarios.
Organizations affected by this vulnerability should immediately implement mitigation strategies including applying the vendor-supplied patch version 6.3.0r24 or higher, which addresses the input validation and output encoding deficiencies. Network segmentation and access controls should be strengthened to limit the number of users with 'security' privileges, while monitoring should be enhanced to detect unusual administrative activities. The remediation process should include thorough review of all web management sessions and user activities for potential exploitation indicators. Security teams should also consider implementing web application firewalls and additional input validation measures to provide defense-in-depth against similar vulnerabilities. This vulnerability highlights the importance of proper input sanitization and output encoding in web-based management interfaces and serves as a reminder of the critical security implications of persistent XSS flaws in privileged management systems.