CVE-2008-1527 in ZyNOS
Summary
by MITRE
ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(PE9) and 3.40(AGD.2) through 3.40(AHQ.3), support authentication over HTTP via a hash string in the hiddenPassword field, which allows remote attackers to obtain access via a replay attack.
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Analysis
by VulDB Data Team • 09/20/2018
The vulnerability described in CVE-2008-1527 affects ZyXEL Prestige series routers including models P-660, P-661, and P-662 that operate with specific firmware versions ranging from 3.40(PE9) through 3.40(AHQ.3). This security flaw resides in the authentication mechanism of these network devices, specifically within how they handle HTTP authentication requests. The issue manifests when the router accepts authentication credentials through a hiddenPassword field that contains a hash string, creating a significant security weakness that can be exploited by remote attackers.
The technical implementation of this vulnerability stems from the router's improper handling of authentication tokens within the HTTP protocol. When users attempt to authenticate to the router's web interface, the system stores and transmits authentication information through a hidden field named hiddenPassword. This field contains a hash value that should ideally be unique and time-bound, but instead functions as a static credential that can be easily captured and reused. The flaw represents a classic case of weak authentication implementation where the hash string lacks proper cryptographic strength or session binding, making it susceptible to replay attacks. This vulnerability directly maps to CWE-310, which addresses cryptographic issues in authentication mechanisms, and specifically relates to CWE-312, which deals with the exposure of sensitive information through hidden fields.
The operational impact of this vulnerability is severe as it allows remote attackers to gain unauthorized administrative access to affected ZyXEL routers without requiring any local network presence or physical access to the device. Attackers can perform replay attacks by capturing the hash string from legitimate authentication requests and then reusing it to establish their own administrative sessions. This provides complete control over the affected network infrastructure, enabling malicious actors to modify router configurations, redirect traffic, implement man-in-the-middle attacks, or establish persistent backdoors. The implications extend beyond simple unauthorized access as compromised routers can serve as entry points for broader network infiltration, potentially affecting all devices connected to the compromised network. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting through network reconnaissance.
Mitigation strategies for this vulnerability require immediate firmware updates from ZyXEL to address the authentication flaw, as the manufacturer would have released patched versions to correct the hash implementation. Network administrators should implement additional security controls such as disabling HTTP access to router management interfaces and requiring HTTPS encryption for all administrative communications. The use of strong authentication mechanisms including multi-factor authentication should be enforced where possible, and network segmentation should be implemented to limit the potential impact of any successful exploitation. Regular vulnerability assessments and network monitoring should be conducted to detect any unauthorized access attempts, and administrators should maintain detailed logs of all router management activities to facilitate incident response efforts. Organizations should also consider implementing network access control lists to restrict access to router management interfaces to only trusted IP addresses and establish robust change management processes for router configuration modifications.