CVE-2017-8839 in Balanace
Summary
by MITRE
XSS via orig_url exists on Peplink Balance 305, 380, 580, 710, 1350, and 2500 devices with firmware before fw-b305hw2_380hw6_580hw2_710hw3_1350hw2_2500-7.0.1-build2093. The affected script is guest/preview.cgi.
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Analysis
by VulDB Data Team • 06/25/2024
The vulnerability CVE-2017-8839 represents a cross-site scripting flaw discovered in Peplink Balance series network appliances including models 305, 380, 580, 710, 1350, and 2500. This issue specifically affects devices running firmware versions prior to fw-b305hw2_380hw6_580hw2_710hw3_1350hw2_2500-7.0.1-build2093. The affected component is the guest/preview.cgi script which processes user input without proper sanitization mechanisms. This vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in web applications that allow attackers to inject malicious scripts into web pages viewed by other users. The flaw exists in the input validation and output encoding processes within the web interface of these network devices.
The technical exploitation of this vulnerability occurs through manipulation of the orig_url parameter within the guest/preview.cgi script. When a user visits a maliciously crafted URL containing malicious script code in the orig_url parameter, the web application fails to properly sanitize or escape the input before rendering it in the browser context. This allows an attacker to inject JavaScript code that executes in the context of other users who access the affected page. The vulnerability is particularly concerning because it affects the guest user functionality of these network appliances, meaning that unauthenticated attackers could potentially exploit this flaw to execute arbitrary code in the browser of authenticated users who access the guest preview feature.
The operational impact of this vulnerability extends beyond simple script injection as it provides attackers with potential access to sensitive network information and user sessions. Network administrators who use these devices may be at risk of having their browser sessions hijacked, potentially allowing attackers to access administrative interfaces or steal session cookies. The attack surface is significant given that these are network infrastructure devices that are often accessible from both internal and external networks, making them attractive targets for attackers seeking to establish persistent access to network environments. This vulnerability aligns with ATT&CK technique T1566 which covers social engineering attacks and T1071 which covers application layer protocol usage, particularly web protocols. The impact is amplified by the fact that these devices typically serve as network gateways, making successful exploitation potentially devastating to network security posture.
Mitigation strategies for CVE-2017-8839 should prioritize immediate firmware updates to versions 7.0.1-build2093 or later where the vulnerability has been addressed. Network administrators should implement network segmentation to limit access to these devices to only authorized personnel and establish proper access controls. Input validation should be strengthened throughout the web application to ensure that all parameters are properly sanitized before processing. Additionally, implementing Content Security Policy headers can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded. Security monitoring should be enhanced to detect unusual traffic patterns or attempts to exploit known vulnerabilities in network infrastructure devices. The vulnerability demonstrates the importance of maintaining up-to-date firmware for network appliances and the critical need for proper input validation in web applications to prevent injection attacks. Organizations should also consider implementing web application firewalls to provide additional protection against similar vulnerabilities in their network infrastructure components.