CVE-2017-7964 in WRE6505
Summary
by MITRE
Zyxel WRE6505 devices have a default TELNET password of 1234 for the root and admin accounts, which makes it easier for remote attackers to conduct DNS hijacking attacks by reconfiguring the built-in dnshijacker process.
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Analysis
by VulDB Data Team • 09/17/2020
The CVE-2017-7964 vulnerability affects Zyxel WRE6505 wireless routers, representing a critical security flaw that stems from poor credential management practices. This device ships with default administrative credentials that are widely known and easily exploitable, specifically using the password "1234" for both root and admin accounts. The vulnerability is classified under CWE-798 as the use of hard-coded credentials, which directly violates fundamental security principles and creates an easily accessible entry point for malicious actors.
The technical implementation of this flaw allows remote attackers to gain unauthorized administrative access to the device through TELNET protocol. Once authenticated, attackers can manipulate the built-in dnshijacker process, which is designed to handle DNS resolution but becomes a vector for malicious activity when compromised. This process can be reconfigured to redirect DNS queries to attacker-controlled servers, enabling DNS hijacking attacks that can redirect users to malicious websites or intercept their network traffic. The vulnerability demonstrates a critical failure in the principle of least privilege, as the default credentials provide full administrative control without requiring additional authentication mechanisms.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it enables sophisticated attack vectors that can compromise entire network infrastructures. DNS hijacking allows attackers to perform man-in-the-middle attacks, redirect users to phishing sites, or inject malicious content into web traffic. The attack surface is particularly dangerous because the vulnerability affects devices that are typically deployed in residential and small business environments where network security is often inadequate. This makes it an attractive target for attackers seeking to establish persistent access points or conduct large-scale phishing campaigns.
The security implications of CVE-2017-7964 align with several ATT&CK framework techniques including T1075 as the use of legitimate credentials for access, T1098 for account manipulation, and T1089 for additional execution capabilities. Network defenders should consider this vulnerability as part of broader reconnaissance activities that could lead to more sophisticated attacks such as credential dumping or lateral movement within compromised networks. The default password issue represents a classic example of how poor security configuration practices can create cascading vulnerabilities that significantly increase the attack surface of affected organizations.
Mitigation strategies for this vulnerability require immediate remediation through credential changes and network segmentation. Organizations should implement mandatory credential rotation policies, disable default accounts, and enforce strong password requirements for all administrative interfaces. Network monitoring should be enhanced to detect suspicious TELNET access patterns and unauthorized configuration changes. The vulnerability also highlights the importance of regular security audits and the need for device firmware updates to address known security flaws. Additionally, implementing network access controls and firewall rules to restrict TELNET access to trusted administrative networks can provide additional defense-in-depth measures against exploitation attempts.