CVE-2017-16953 in ZXDSL 831CII
Summary
by MITRE
connoppp.cgi on ZTE ZXDSL 831CII devices does not require HTTP Basic Authentication, which allows remote attackers to modify the PPPoE configuration or set up a malicious configuration via a GET request.
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Analysis
by VulDB Data Team • 09/25/2024
The vulnerability identified as CVE-2017-16953 affects ZTE ZXDSL 831CII broadband access devices where the connoppp.cgi web script fails to implement proper authentication mechanisms. This represents a critical security flaw in the device's web interface administration system, as it exposes sensitive configuration functions to unauthenticated remote attackers. The absence of HTTP Basic Authentication requirements creates an exploitable entry point that allows malicious actors to manipulate the device's Point-to-Point Protocol over Ethernet configuration without requiring valid credentials.
The technical nature of this vulnerability stems from the lack of authentication checks within the connoppp.cgi script, which is designed to manage PPPoE connection parameters. When attackers send a GET request to this specific endpoint, they can directly modify the device's network configuration settings. This flaw operates at the application layer and demonstrates poor input validation and access control implementation. The vulnerability aligns with CWE-287 which addresses improper authentication issues, and represents a classic case of insufficient authorization controls within web applications.
From an operational perspective, this vulnerability poses significant risks to network security and device integrity. Remote attackers can exploit this weakness to establish malicious PPPoE connections, potentially redirecting traffic through unauthorized networks or creating backdoor access points. The impact extends beyond simple configuration changes as these modifications can compromise the entire network infrastructure connected to the affected device. Network administrators lose control over critical connectivity parameters, potentially enabling man-in-the-middle attacks or unauthorized network access. The vulnerability affects the device's confidentiality, integrity, and availability by allowing unauthorized modifications to core network configuration data.
The attack vector for this vulnerability is particularly concerning as it requires no prior authentication credentials and can be executed remotely over the network. This makes it highly attractive to attackers who can leverage automated scanning tools to identify vulnerable devices across the internet. The exploitation process involves simple HTTP GET requests that can be crafted using basic web tools or scripting languages, making this vulnerability accessible to attackers with minimal technical expertise. According to ATT&CK framework, this vulnerability maps to T1071.004 for application layer protocol usage and T1566 for phishing techniques that could be used to initially compromise devices.
Mitigation strategies for this vulnerability should include immediate implementation of network segmentation to isolate affected devices from critical network segments. Network administrators should ensure that all web-based management interfaces require strong authentication mechanisms including HTTP Basic Authentication or more robust alternatives like OAuth or multi-factor authentication. Regular firmware updates from ZTE should be implemented to address this specific vulnerability, and device access should be restricted to authorized network segments only. Network monitoring should be enhanced to detect unusual configuration changes or unauthorized access attempts to management interfaces. Additionally, organizations should consider implementing network access control policies that limit the exposure of administrative interfaces to only necessary trusted sources and establish regular security audits to identify similar authentication bypass vulnerabilities in other network devices.