CVE-2018-15439 in Small Business Switches
Summary
by MITRE
A vulnerability in the Cisco Small Business Switches software could allow an unauthenticated, remote attacker to bypass the user authentication mechanism of an affected device. The vulnerability exists because under specific circumstances, the affected software enables a privileged user account without notifying administrators of the system. An attacker could exploit this vulnerability by using this account to log in to an affected device and execute commands with full admin rights. Cisco has not released software updates that address this vulnerability. This advisory will be updated with fixed software information once fixed software becomes available. There is a workaround to address this vulnerability.
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Analysis
by VulDB Data Team • 06/05/2023
This vulnerability resides within Cisco Small Business Switches software and represents a critical authentication bypass flaw that enables remote attackers to gain full administrative privileges without proper credentials. The vulnerability stems from the software's handling of privileged user accounts under specific conditions, where the system automatically creates and enables an administrative account without alerting system administrators of this security compromise. This design flaw creates a backdoor scenario where unauthorized individuals can exploit the system through a hidden administrative account, effectively circumventing all standard authentication mechanisms. The vulnerability is particularly concerning because it operates without administrator knowledge, making it extremely difficult to detect and remediate through normal security monitoring procedures.
The technical implementation of this vulnerability involves the software's privilege management system failing to properly validate or restrict access to administrative functions. When the affected conditions are met, the system automatically provisions a privileged account that remains hidden from standard administrative interfaces and audit trails. This account can be leveraged by remote attackers to establish authenticated sessions with full administrative capabilities, allowing them to execute arbitrary commands, modify system configurations, and potentially access sensitive network data. The exploitability of this vulnerability is heightened by its remote nature, meaning attackers do not require physical access or local network presence to exploit the flaw, and the lack of notification to system administrators means the compromise can persist undetected for extended periods. This vulnerability directly maps to CWE-284 (Improper Access Control) and aligns with ATT&CK technique T1078 (Valid Accounts) as it leverages legitimate administrative credentials obtained through improper system configuration rather than brute force or credential theft methods.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it fundamentally undermines the security posture of affected networks by providing persistent administrative capabilities to attackers. Network administrators lose visibility into critical system activities and configuration changes that may be occurring without their knowledge, potentially allowing attackers to establish persistent access points, modify network policies, or redirect traffic flows. The lack of software updates from Cisco at the time of disclosure meant that organizations had to rely on workarounds and manual security measures to protect their systems, creating a window of vulnerability that attackers could exploit for extended periods. Organizations with multiple affected switches would face cascading security risks, as a single compromised device could potentially provide attackers with a foothold to expand access throughout the network infrastructure. This vulnerability also creates challenges for compliance requirements and audit processes, as the unauthorized administrative access would not appear in standard logging or monitoring systems.
Organizations affected by this vulnerability should implement immediate workarounds while planning for more comprehensive security measures. The recommended approach includes disabling unused administrative accounts, implementing network segmentation to limit access to critical switches, and deploying enhanced monitoring solutions to detect anomalous administrative activities. Network administrators should also conduct thorough audits of all switch configurations and establish baseline configurations that prevent the automatic creation of privileged accounts. Implementing network access control lists and firewall rules to restrict access to switch management interfaces can help mitigate the risk of remote exploitation. Additionally, organizations should consider deploying intrusion detection systems specifically configured to monitor for administrative access patterns and unauthorized configuration changes. The vulnerability highlights the importance of regular security assessments and the need for robust change management processes to prevent unauthorized privilege escalation scenarios, aligning with security frameworks that emphasize continuous monitoring and proactive threat detection measures.