CVE-2021-1239 in FirePOWER Management Center
Summary
by MITRE • 01/14/2021
Multiple vulnerabilities in the web-based management interface of Cisco Firepower Management Center (FMC) could allow an authenticated, remote attacker to conduct a stored cross-site scripting (XSS) attack against a user of the interface of an affected system. The vulnerabilities exist because the web-based management interface does not properly validate user-supplied input. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. 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.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 02/14/2021
The vulnerability identified as CVE-2021-1239 affects Cisco Firepower Management Center (FMC) versions 6.2.0 through 6.4.0, representing a critical stored cross-site scripting flaw that undermines the security of the web-based management interface. This vulnerability stems from inadequate input validation mechanisms within the FMC's web application, creating an attack vector that allows authenticated remote adversaries to inject malicious scripts into the system's interface. The flaw specifically resides in how the management console processes user-supplied data, failing to properly sanitize or escape input parameters that are subsequently rendered in web pages without adequate security measures.
The technical exploitation of this vulnerability occurs through a sophisticated social engineering approach where attackers craft malicious links designed to target authenticated users of the FMC interface. When a victim user clicks on these crafted links, the malicious script code becomes permanently stored within the application's database or session management system, thereby executing in the context of the victim's browser session. This stored nature of the XSS vulnerability means that the malicious payload persists and affects any user who subsequently accesses the affected interface components, making the attack particularly dangerous in multi-user environments where administrators and security personnel regularly interact with the management console.
The operational impact of CVE-2021-1239 extends beyond simple script execution, as successful exploitation can provide attackers with the ability to access sensitive browser-based information and potentially escalate privileges within the FMC environment. Attackers could leverage this vulnerability to steal session cookies, perform unauthorized administrative actions, access confidential network security policies, or exfiltrate sensitive configuration data. The vulnerability's classification aligns with CWE-79, which specifically addresses cross-site scripting flaws, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for scripting languages and T1566 for social engineering tactics. The attack surface is particularly concerning given that FMC serves as a central management point for network security policies and threat intelligence, making successful exploitation a significant compromise of enterprise security infrastructure.
Organizations affected by this vulnerability should immediately implement mitigations including applying the latest security patches released by Cisco, which address the input validation deficiencies in the web interface components. Network segmentation and monitoring of FMC management traffic can help detect anomalous behavior indicative of exploitation attempts. Additional protective measures include implementing web application firewalls to filter malicious requests, conducting regular security assessments of the management interface, and establishing strict access controls with role-based permissions to limit the potential impact of successful attacks. The vulnerability underscores the critical importance of maintaining up-to-date security controls and demonstrates how seemingly minor input validation flaws can create substantial security risks in enterprise security management platforms.