CVE-2011-4499 in Linksys Wrt54gs Router
Summary
by MITRE
The UPnP IGD implementation in the Broadcom UPnP stack on the Cisco Linksys WRT54G with firmware before 4.30.5, WRT54GS v1 through v3 with firmware before 4.71.1, and WRT54GS v4 with firmware before 1.06.1 allows remote attackers to establish arbitrary port mappings by sending a UPnP AddPortMapping action in a SOAP request to the WAN interface, related to an "external forwarding" vulnerability.
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Analysis
by VulDB Data Team • 08/07/2024
The vulnerability described in CVE-2011-4499 represents a critical security flaw in the Universal Plug and Play Internet Gateway Device implementation within Broadcom's UPnP stack on various Cisco Linksys WRT54G and WRT54GS router models. This issue stems from improper input validation and authorization mechanisms within the UPnP protocol handling, specifically affecting devices running firmware versions prior to the mentioned security patches. The vulnerability exists in the WAN interface of these routers, where the UPnP IGD (Internet Gateway Device) service fails to properly authenticate or validate incoming SOAP requests that attempt to establish port mappings.
The technical exploitation of this vulnerability occurs through a straightforward attack vector where remote attackers can send malicious UPnP AddPortMapping action requests in SOAP format directly to the WAN interface of affected routers. This flaw essentially allows unauthorized parties to programmatically configure port forwarding rules on the router without proper authentication, effectively bypassing the router's normal security controls. The vulnerability is categorized under CWE-284, which addresses improper access control in software implementations, and represents a classic case of insufficient authorization checks within network services. The attack leverages the legitimate UPnP protocol functionality but abuses it to create unauthorized network access points.
The operational impact of this vulnerability is severe and far-reaching for affected networks. Attackers who successfully exploit this flaw can establish arbitrary port mappings that allow them to forward traffic from the internet directly to internal network devices, effectively creating backdoors into the local network. This capability enables various malicious activities including but not limited to remote code execution, data exfiltration, network reconnaissance, and establishment of persistent access points. The vulnerability particularly affects home and small office networks where these routers are commonly deployed, potentially exposing sensitive internal systems to external threats. According to ATT&CK framework, this vulnerability maps to T1071.004 (Application Layer Protocol: DNS) and T1021.001 (Remote Services: Remote Desktop Protocol) through the port forwarding capabilities, though the primary impact stems from T1071.001 as the attack uses UPnP protocol for network manipulation.
The exploitation of this vulnerability demonstrates a fundamental flaw in the router's security architecture where network services that should be protected by authentication and authorization mechanisms are exposed to unauthenticated remote access. The vulnerability affects multiple generations of Cisco Linksys WRT54G and WRT54GS routers, indicating a widespread issue within the firmware implementation that was not properly addressed through standard security controls. Organizations and individuals using affected router models are at significant risk of network compromise, as the vulnerability allows attackers to bypass the router's normal firewall protections and establish persistent network access. The attack requires minimal technical expertise to execute, making it particularly dangerous as it can be exploited by threat actors with varying levels of sophistication. This vulnerability highlights the critical importance of proper input validation and authorization controls in network services, particularly those that provide direct access to network configuration functions. The issue also underscores the need for regular firmware updates and proper security testing of embedded network devices to prevent such exposure of critical network functionality to unauthorized access.