CVE-2008-1521 in ZyNOS
Summary
by MITRE
ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), allow remote authenticated users to gain privileges by accessing administrative URIs, as demonstrated by rpSysAdmin.html.
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Analysis
by VulDB Data Team • 09/20/2018
The vulnerability identified as CVE-2008-1521 affects ZyXEL Prestige series routers, specifically models P-660 and P-661, when operating with firmware versions ranging from 3.40(AGD.2) through 3.40(AHQ.3). This represents a critical privilege escalation flaw that enables authenticated remote attackers to elevate their access rights within the router's administrative interface. The vulnerability manifests through the improper handling of administrative URIs, particularly the rpSysAdmin.html endpoint, which should normally require elevated privileges to access but instead allows unauthorized privilege elevation.
This security flaw constitutes a serious authorization bypass vulnerability that directly violates the principle of least privilege and proper access control mechanisms. The technical implementation appears to lack adequate authentication checks or role-based access controls within the router's web administration interface. When an authenticated user accesses certain administrative URIs, the system fails to properly validate whether the requesting user possesses the necessary administrative privileges, allowing them to access restricted administrative functions that should be limited to authorized administrators only. The vulnerability falls under the category of improper access control as defined by CWE-285, which specifically addresses issues where systems fail to properly enforce access restrictions.
The operational impact of this vulnerability is significant as it allows remote attackers who have already gained access to a legitimate user account to escalate their privileges without requiring additional authentication credentials. This creates a pathway for attackers to gain full administrative control over the affected routers, potentially enabling them to modify network configurations, access sensitive data, redirect traffic, or establish persistent access points within the network. The remote nature of the vulnerability means that attackers do not need physical access to the device or local network presence, making it particularly dangerous for network administrators who may not be aware of the compromised accounts. This vulnerability aligns with ATT&CK technique T1068, which describes privilege escalation through the exploitation of legitimate credentials.
The exploitation of this vulnerability demonstrates a fundamental flaw in the router's security architecture, where the administrative interface does not properly enforce the separation between user-level and administrator-level functions. The specific URI rpSysAdmin.html serves as the attack vector, suggesting that the router's web server implementation contains a flaw in how it processes administrative requests. This type of vulnerability is particularly concerning in enterprise environments where routers serve as critical network infrastructure components, as it can lead to complete network compromise. Organizations using affected ZyXEL Prestige routers should immediately implement mitigations including firmware updates, network segmentation, and monitoring for unauthorized administrative access attempts.
Security professionals should note that this vulnerability represents a classic example of insufficient authorization checks in web applications and network device interfaces. The flaw indicates that the router's authentication system properly validates user credentials but fails to properly enforce privilege levels during administrative operations. This type of vulnerability is commonly found in embedded network devices where security considerations may not have been prioritized during development, leading to implementations that do not follow secure coding practices. The vulnerability's classification as a privilege escalation issue highlights the need for comprehensive security testing of administrative interfaces, particularly in network infrastructure devices that are frequently targeted by attackers seeking persistent access to networks.