CVE-2018-5789 in Networks ExtremeWireless WiNG
Summary
by MITRE
An issue was discovered in Extreme Networks ExtremeWireless WiNG 5.x before 5.8.6.9 and 5.9.x before 5.9.1.3. There is a Remote, Unauthenticated XML Entity Expansion Denial of Service on the WiNG Access Point / Controller via crafted XML entities to the Web User Interface.
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Analysis
by VulDB Data Team • 01/01/2020
The vulnerability identified as CVE-2018-5789 represents a critical denial of service weakness within Extreme Networks ExtremeWireless WiNG access point and controller software versions prior to specific patches. This issue affects both the 5.x release line before 5.8.6.9 and the 5.9.x line before 5.9.1.3, creating a significant operational risk for organizations relying on these wireless infrastructure components. The vulnerability manifests through a remote, unauthenticated XML entity expansion attack that targets the web user interface of the affected systems, making it particularly dangerous as it can be exploited without requiring any valid credentials or network access privileges.
The technical flaw stems from insufficient input validation within the XML processing mechanism of the web interface component. When the system receives malformed XML data containing crafted entity references, it fails to properly limit the expansion of these entities, leading to excessive resource consumption and ultimately system unresponsiveness. This vulnerability directly maps to CWE-400, which categorizes it as an Uncontrolled Resource Consumption vulnerability, specifically focusing on XML external entity processing. The flaw operates by allowing attackers to construct XML documents that reference external entities or create recursive entity definitions, causing the system to expend considerable computational resources in processing these requests.
The operational impact of this vulnerability extends beyond simple service disruption as it can effectively render entire wireless networks inaccessible to legitimate users and administrators. Attackers exploiting this weakness can cause the affected access points or controllers to become unresponsive, leading to complete loss of wireless connectivity for connected devices. This disruption can cascade throughout enterprise networks, particularly in environments where wireless infrastructure serves as the primary or sole connectivity mechanism for critical business operations. The unauthenticated nature of the attack means that any remote user can potentially exploit this vulnerability, making it a particularly attractive target for malicious actors seeking to disrupt network operations. Organizations may face significant downtime costs and potential business interruption when such attacks occur, especially in mission-critical environments where wireless connectivity is essential.
Mitigation strategies for CVE-2018-5789 should focus on immediate patch deployment to upgrade affected systems to versions 5.8.6.9 or 5.9.1.3, which contain the necessary fixes for the XML entity expansion vulnerability. Network administrators should also implement network-level controls to restrict access to the web user interface, particularly by blocking unnecessary external access to the affected ports and services. Additionally, implementing XML parsing restrictions and configuring entity expansion limits within the web application framework can provide additional defense-in-depth measures. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to denial of service and privilege escalation, as the attack can potentially be used to gain control over network infrastructure. Organizations should also consider implementing network monitoring solutions that can detect unusual XML processing patterns or resource consumption spikes that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and resource limiting in web applications, particularly those handling XML data, and serves as a reminder of the critical need for regular security updates and vulnerability management processes.