CVE-2006-2562 in P-335WT router
Summary
by MITRE
ZyXEL P-335WT router allows remote attackers to bypass access restrictions and conduct unauthorized operations via a UPnP request with a modified InternalClient parameter, which is not validated, as demonstrated by using AddPortMapping to forward arbitrary traffic.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/05/2017
The CVE-2006-2562 vulnerability affects ZyXEL P-335WT routers and represents a critical access control flaw within the Universal Plug and Play UPnP implementation. This vulnerability stems from insufficient input validation in the router's UPnP service, specifically in how it processes the InternalClient parameter within UPnP requests. The flaw allows remote attackers to manipulate the UPnP protocol to bypass legitimate access controls and execute unauthorized network operations.
The technical exploitation of this vulnerability occurs through the manipulation of UPnP AddPortMapping requests where an attacker can modify the InternalClient parameter to point to arbitrary internal network addresses. This parameter validation failure enables attackers to redirect network traffic to unintended destinations without proper authentication or authorization. The vulnerability specifically impacts the router's ability to enforce network access restrictions, as the UPnP service fails to validate whether the requested internal client address is legitimate or authorized for port mapping operations.
This vulnerability has significant operational impact as it allows remote attackers to perform unauthorized network operations including port forwarding, service exposure, and potential network reconnaissance. Attackers can leverage this flaw to redirect traffic to internal systems, potentially exposing sensitive services or creating backdoors within the network. The remote nature of the attack means that adversaries do not require physical access or local network credentials to exploit this vulnerability, making it particularly dangerous in environments where routers are exposed to untrusted networks.
The vulnerability aligns with CWE-284, which describes improper access control in software systems, and represents a classic case of insufficient input validation in network services. From an ATT&CK framework perspective, this vulnerability maps to T1071.004 for application layer protocol usage and T1046 for network service scanning, as attackers can use the UPnP interface to enumerate and manipulate network services. The flaw essentially allows adversaries to perform privilege escalation through service manipulation, bypassing normal network access controls.
Mitigation strategies for this vulnerability include disabling UPnP functionality on affected routers when not required for legitimate network operations, implementing network segmentation to limit exposure of vulnerable devices, and applying firmware updates from ZyXEL if available. Network administrators should also monitor for unauthorized UPnP activities and implement firewall rules to restrict UPnP traffic between internal and external networks. The most effective long-term solution involves upgrading to router firmware versions that properly validate UPnP parameters and enforce access controls for network service modifications.
The vulnerability demonstrates the importance of input validation in network services and highlights how seemingly benign protocols like UPnP can become attack vectors when not properly secured. Organizations should implement comprehensive network security monitoring to detect anomalous UPnP activities and maintain updated vulnerability assessments to identify similar flaws in other network equipment. This case underscores the necessity of secure coding practices and proper access control implementation in embedded network devices that handle network configuration changes.