CVE-2017-16878 in PAN-OS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Captive Portal function in Palo Alto Networks PAN-OS before 8.0.7 allows remote attackers to inject arbitrary web script or HTML by leveraging an unspecified configuration.
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Analysis
by VulDB Data Team • 01/20/2023
The vulnerability identified as CVE-2017-16878 represents a critical cross-site scripting flaw within the Captive Portal functionality of Palo Alto Networks PAN-OS versions prior to 8.0.7. This weakness exposes organizations to significant security risks by allowing remote attackers to execute malicious web scripts or HTML code within the context of authenticated user sessions. The vulnerability specifically affects the captive portal implementation that is commonly used for network access control and user authentication in enterprise environments.
The technical nature of this flaw stems from insufficient input validation and output encoding within the captive portal module of the PAN-OS operating system. When users attempt to access network resources through the captive portal interface, the system fails to properly sanitize user-supplied input parameters that are subsequently reflected back to the browser. This lack of proper sanitization creates an avenue for attackers to inject malicious payloads that can execute in the victim's browser context, potentially leading to session hijacking, credential theft, or further exploitation of the compromised system. The vulnerability manifests when attackers leverage unspecified configuration elements within the captive portal implementation to deliver their malicious payloads.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable sophisticated attack chains that compromise entire network infrastructures. An attacker who successfully exploits this vulnerability can establish persistent access to authenticated user sessions, potentially gaining access to sensitive network resources, internal systems, and confidential data. The captive portal functionality typically serves as an entry point for network access control, making this vulnerability particularly dangerous as it can provide attackers with a foothold to escalate privileges and move laterally within the network environment. Organizations using affected PAN-OS versions face potential data breaches, unauthorized access to network resources, and compliance violations due to the exposure of sensitive information through the compromised authentication mechanism.
Mitigation strategies for CVE-2017-16878 require immediate implementation of the vendor-provided security patches and updates to PAN-OS versions 8.0.7 and later. Organizations should also implement additional defensive measures including thorough input validation for all captive portal parameters, enhanced web application firewalls, and regular security assessments of network access control systems. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and maps to ATT&CK technique T1078 for valid accounts and T1531 for credential stuffing, as attackers can leverage compromised sessions to maintain persistent access. Network administrators should also consider implementing network segmentation, monitoring for anomalous captive portal traffic patterns, and conducting regular penetration testing to identify potential exploitation vectors. Additionally, organizations should review their existing security policies and procedures to ensure proper handling of authentication flows and implement comprehensive logging and alerting mechanisms to detect potential exploitation attempts.