CVE-2011-4500 in WRT54GX
Summary
by MITRE
The UPnP IGD implementation on the Cisco Linksys WRT54GX with firmware 2.00.05, when UPnP is enabled, configures the SOAP server to listen on the WAN port, which allows remote attackers to administer the firewall via SOAP requests.
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Analysis
by VulDB Data Team • 08/07/2024
The vulnerability identified as CVE-2011-4500 represents a critical security flaw in the Universal Plug and Play Internet Gateway Device implementation within Cisco Linksys WRT54GX wireless routers. This issue manifests when the UPnP functionality is enabled in firmware version 2.00.05, creating an unintended exposure that fundamentally compromises network security. The vulnerability stems from improper network configuration where the SOAP server component, designed for local network administration, is incorrectly configured to accept connections from external networks through the WAN port interface.
The technical root cause of this vulnerability lies in the improper binding of the SOAP server to network interfaces, specifically allowing external access to the router's administrative functions. This misconfiguration creates an attack surface that violates fundamental network security principles by exposing internal management interfaces to unauthenticated remote users. The flaw operates at the application layer of the network stack, specifically within the UPnP service implementation that handles Simple Object Access Protocol requests. According to CWE-284, this represents an improper access control vulnerability where the system fails to properly restrict access to privileged functions, and aligns with ATT&CK technique T1021.001 for remote services and T1071.004 for application layer protocols.
The operational impact of this vulnerability is severe and multifaceted, as it provides remote attackers with complete administrative control over the affected router's firewall configuration. Attackers can manipulate port forwarding rules, modify firewall policies, and potentially gain unauthorized access to internal network resources through the compromised router. This vulnerability enables a wide range of malicious activities including but not limited to port redirection attacks, denial of service conditions, and establishing persistent access points within the network. The exposure through the WAN port means that attackers do not require physical access or local network presence to exploit this vulnerability, making it particularly dangerous for home and small office environments where such devices are commonly deployed without proper network segmentation.
Mitigation strategies for this vulnerability should prioritize immediate action through firmware updates from Cisco, as the manufacturer would have released patches addressing the improper network interface binding. Network administrators should disable UPnP functionality entirely on affected devices when not actively required, implementing the principle of least privilege for network services. Additional protective measures include configuring firewall rules to block external access to the UPnP SOAP ports, typically TCP port 1900, and implementing network segmentation to isolate potentially compromised devices. The vulnerability demonstrates the critical importance of secure configuration management and regular security assessments, particularly for network infrastructure devices that are often overlooked in security monitoring programs. Organizations should also consider implementing network access control measures and continuous monitoring to detect unauthorized changes to router configurations that might indicate exploitation of this vulnerability.