CVE-2008-1526 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), do not use a salt when calculating an MD5 password hash, which makes it easier for attackers to crack passwords.
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Analysis
by VulDB Data Team • 09/20/2018
The vulnerability identified as CVE-2008-1526 affects ZyXEL Prestige series routers, specifically models P-660, P-661, and P-662, which are widely deployed in both enterprise and residential networking environments. These devices operate with firmware versions ranging from 3.40(PE9) through 3.40(AHQ.3), creating a substantial attack surface given the router's role as a primary network gateway and administrative interface. The flaw lies in the authentication mechanism implementation where the routers fail to employ proper salting techniques during MD5 hash calculations for user passwords. This represents a fundamental cryptographic weakness that significantly undermines the security posture of affected devices, particularly when considering the widespread use of these models in critical infrastructure environments.
The technical implementation flaw stems from the absence of cryptographic salt in the MD5 hashing process, which creates predictable hash outputs for identical passwords across different router instances. Without salt, attackers can leverage precomputed rainbow tables and dictionary attacks to efficiently reverse engineer user credentials, as the same password will always produce the same hash value. This vulnerability directly maps to CWE-759, which addresses the use of a one-way hash without a salt, and CWE-310, which covers cryptographic issues related to hash functions. The weakness creates a direct path for credential compromise that bypasses the intended security controls, allowing unauthorized access to router administration interfaces and potentially enabling further network infiltration.
The operational impact of this vulnerability extends beyond simple credential theft, as compromised router access can lead to complete network compromise through various attack vectors. Once attackers gain administrative access, they can modify router configurations, redirect traffic through malicious proxies, implement man-in-the-middle attacks, or establish persistent backdoors within the network infrastructure. The vulnerability also aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting through network attacks. Network administrators may unknowingly provide attackers with a foothold that can persist across network reconfigurations, as the compromised credentials remain valid for extended periods without password rotation.
Mitigation strategies for this vulnerability require immediate firmware updates from ZyXEL, as the manufacturer has released patches addressing the cryptographic weakness. Organizations should implement comprehensive network monitoring to detect unauthorized access attempts and credential harvesting activities. Network segmentation and additional authentication layers such as two-factor authentication should be implemented where possible. Security teams must conduct thorough inventory audits to identify all affected router models within their infrastructure and prioritize remediation efforts based on risk assessment. The vulnerability demonstrates the critical importance of proper cryptographic implementation in network devices, as the absence of salt in hash functions creates an exploitable weakness that can be leveraged across multiple attack scenarios.