CVE-2019-15969 in Web Security Appliance
Summary
by MITRE
A vulnerability in the web-based management interface of Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to conduct cross-site scripting (XSS) attacks against a user of the interface of an affected device. The vulnerability is due to insufficient validation of user-supplied input by the web-based management interface of an affected device. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script or HTML code in the context of the interface, which could allow the attacker to gain access to sensitive, browser-based information.
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Analysis
by VulDB Data Team • 09/23/2020
The vulnerability identified as CVE-2019-15969 represents a critical cross-site scripting flaw within Cisco Web Security Appliance's web-based management interface. This security weakness resides in the insufficient validation mechanisms that govern user-supplied input entering the system through the graphical user interface. The affected device operates as a web security appliance designed to filter and monitor web traffic, making its management interface a prime target for malicious actors seeking to compromise the security posture of enterprise networks. The vulnerability specifically affects the web-based management interface of Cisco WSA appliances, which are widely deployed in enterprise environments to provide web filtering, threat prevention, and security policy enforcement capabilities.
The technical exploitation of this vulnerability occurs through a classic social engineering attack vector where an attacker crafts malicious links designed to exploit the inadequate input validation mechanisms. When an unsuspecting user with valid access privileges clicks on the crafted link, the malicious payload executes within the browser context of the management interface. This flaw falls under CWE-79 which specifically addresses Cross-Site Scripting vulnerabilities, and aligns with ATT&CK technique T1059.007 for script execution through web interfaces. The vulnerability does not require authentication to the management interface itself, making it particularly dangerous as it can be exploited against any user who accesses the interface, regardless of their privilege level. The execution of arbitrary code in the browser context of the interface allows attackers to potentially steal session cookies, credentials, or other sensitive information stored in the browser's memory.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to manipulate the web interface in ways that could compromise the entire security infrastructure. An attacker could leverage this vulnerability to establish persistent access to the management interface, potentially allowing them to modify security policies, disable protection mechanisms, or exfiltrate sensitive configuration data. The attack scenario typically involves an attacker identifying a target user who regularly accesses the WSA management interface and sending them a malicious link through phishing campaigns or other social engineering techniques. This vulnerability particularly threatens organizations that rely heavily on the WSA for their web security posture, as successful exploitation could lead to complete compromise of the web filtering and security enforcement capabilities. The vulnerability also poses risks to the confidentiality and integrity of web traffic monitoring data, as attackers could manipulate the interface to hide malicious activities or redirect traffic through compromised paths.
Organizations should implement immediate mitigations including applying the latest security patches provided by Cisco, which address the input validation deficiencies in the web interface. Network segmentation and monitoring of management interface access can help detect suspicious activities, while user education programs should emphasize the dangers of clicking untrusted links in management interfaces. The implementation of web application firewalls and content security policies can provide additional layers of protection against XSS attacks. Security teams should also conduct regular vulnerability assessments targeting web interfaces and implement proper input sanitization controls throughout their applications. The vulnerability demonstrates the critical importance of validating all user-supplied input and highlights the necessity of following secure coding practices as outlined in OWASP Top 10 and NIST cybersecurity guidelines. Regular security audits of web-based management interfaces should be conducted to identify and remediate similar input validation weaknesses that could provide attackers with similar attack vectors.