CVE-2020-3356 in Data Center Network Manager
Summary
by MITRE
A vulnerability in the web-based management interface of Cisco Data Center Network Manager (DCNM) could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user of the interface. The vulnerability is due to insufficient input validation by the web-based management interface. An attacker could exploit this vulnerability by interacting with the interface in a way that injects malicious content in a log file. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2020-3356 represents a critical cross-site scripting flaw within Cisco Data Center Network Manager's web-based management interface. This weakness specifically targets the application's insufficient input validation mechanisms, creating an exploitable condition that allows unauthenticated remote attackers to inject malicious code into the system. The vulnerability resides in the interface's handling of user-supplied input, particularly when processing data that gets logged within the system's administrative environment. The flaw enables attackers to manipulate the web interface through crafted input that ultimately gets rendered back to users, creating a persistent XSS vector that can be leveraged for various malicious activities.
The technical exploitation of this vulnerability occurs through the manipulation of input fields within the DCNM interface, where attacker-controlled data gets processed and stored in log files without proper sanitization. When legitimate users subsequently view these log entries through the web interface, the malicious scripts embedded within the log data execute in the context of the victim's browser session. This execution model aligns with CWE-79, which categorizes cross-site scripting vulnerabilities as a result of insufficient input validation and output encoding. The attack vector specifically targets the web application's trust in user input, where the system fails to properly validate or escape data before rendering it back to users, creating a persistent code execution environment that can be leveraged for session hijacking, credential theft, or data exfiltration.
The operational impact of CVE-2020-3356 extends beyond simple script injection, as it provides attackers with the capability to establish persistent access to the DCNM management interface. This vulnerability can be exploited to gain unauthorized access to sensitive network management information, potentially allowing attackers to view or modify network configurations, access administrative functions, or extract confidential data from the management interface. The remote nature of the attack means that exploitation can occur from anywhere on the internet without requiring prior authentication, making this vulnerability particularly dangerous for organizations that expose their DCNM interfaces to external networks. The attack aligns with ATT&CK technique T1059.007, which covers the use of script-based commands to execute malicious code, and T1566.001, which addresses the exploitation of web applications through input validation flaws.
Organizations affected by this vulnerability should implement immediate mitigations including input validation and output encoding controls to prevent malicious content from being stored or executed within the web interface. The recommended approach involves implementing comprehensive data sanitization mechanisms that filter and escape user-supplied input before it is processed or stored in log files. Network segmentation and access controls should be enhanced to limit exposure of the DCNM interface to trusted networks only, while regular security assessments should monitor for potential exploitation attempts. Cisco has released patches and updates to address this vulnerability, and organizations should prioritize applying these security updates to prevent exploitation. The remediation strategy should also include monitoring log files for suspicious activity and implementing web application firewalls to detect and block potential XSS attempts, ensuring that the system maintains proper input validation controls to prevent similar vulnerabilities from being exploited in the future.