CVE-2017-2336 in ScreenOS
Summary
by MITRE
A reflected cross site scripting vulnerability in NetScreen WebUI of Juniper Networks Juniper NetScreen Firewall+VPN running ScreenOS allows a network based attacker to inject HTML/JavaScript content into the management session of other users including the administrator. This enables the attacker 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 • 12/12/2022
The vulnerability identified as CVE-2017-2336 represents a critical reflected cross site scripting flaw within the NetScreen WebUI interface of Juniper Networks' ScreenOS operating system. This vulnerability specifically targets the SSG Series firewall and VPN appliances running ScreenOS version 6.3.0 prior to 6.3.0r24, creating a significant security risk for organizations relying on these devices for network protection. The flaw stems from inadequate input validation and output encoding mechanisms within the web management interface, allowing malicious actors to inject malicious code that persists in user sessions. This vulnerability is categorized under CWE-79 as a failure to sanitize user input, specifically manifesting as reflected cross site scripting that enables attackers to manipulate the web application's behavior.
The technical exploitation of this vulnerability occurs through network-based attacks where an attacker crafts malicious HTTP requests containing HTML or JavaScript payloads that are reflected back to the victim's browser through the vulnerable web interface. When authenticated users, including administrators, interact with the compromised web application, their browsers execute the injected malicious code within the context of their active sessions. This reflected XSS attack vector allows the attacker to effectively hijack administrative sessions and execute commands with full administrative privileges. The vulnerability's impact extends beyond simple data theft as it provides complete control over the affected firewall appliance, enabling attackers to modify firewall rules, access network traffic, and potentially pivot to other systems within the network. This represents a direct violation of the principle of least privilege and allows for privilege escalation attacks that align with ATT&CK technique T1068.
The operational impact of CVE-2017-2336 is severe and multifaceted, as it compromises the fundamental security posture of affected networks. Organizations utilizing vulnerable ScreenOS appliances face the risk of complete network compromise, with attackers able to bypass firewall protections, monitor network traffic, and modify security policies in real-time. The vulnerability's persistence in management sessions means that even brief interactions with compromised web pages could result in persistent backdoors or complete administrative takeover. This threat landscape aligns with ATT&CK tactic T1566, which covers social engineering techniques, as the vulnerability exploits user trust in legitimate web interfaces. The attack surface is particularly concerning for organizations that rely heavily on these appliances for network segmentation and security enforcement, as the compromise of a single device can potentially expose the entire network infrastructure to unauthorized access and manipulation.
Mitigation strategies for this vulnerability require immediate patching of affected devices to ScreenOS version 6.3.0r24 or later, which contains the necessary security fixes to address the reflected XSS flaw. Network administrators should implement additional defensive measures including monitoring for suspicious web traffic patterns, implementing web application firewalls to detect and block malicious payloads, and conducting thorough security assessments of the affected appliances. Organizations should also consider disabling the web management interface when not actively required, implementing strong authentication controls, and establishing network segmentation to limit the potential impact of successful exploitation. The remediation process must include comprehensive testing of patched systems to ensure that the vulnerability is fully resolved without introducing new operational issues. Additionally, organizations should conduct regular security audits of their network infrastructure to identify and remediate similar vulnerabilities across all network devices and applications, following security frameworks such as NIST SP 800-53 controls for information system security.