CVE-2018-0093 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 a reflected cross-site scripting (XSS) attack against a user of the web-based management 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 code in the context of the interface or allow the attacker to access sensitive browser-based information. Cisco Bug IDs: CSCvf37392.
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Analysis
by VulDB Data Team • 02/01/2021
The vulnerability identified as CVE-2018-0093 affects Cisco Web Security Appliance (WSA) devices, specifically targeting their web-based management interface. This represents a critical security flaw that undermines the integrity of the device's administrative access controls, potentially allowing unauthorized users to compromise the security posture of network infrastructure. The vulnerability stems from inadequate input validation mechanisms within the web interface, creating an exploitable entry point for malicious actors seeking to manipulate the system through browser-based attacks.
This reflected cross-site scripting vulnerability operates through a classic attack vector where an attacker crafts malicious links designed to exploit the insufficient input validation in the WSA's web interface. The flaw exists because the system fails to properly sanitize user-supplied input before processing and displaying it within the interface context. When a victim user clicks on the crafted malicious link, the web application reflects the attacker's input back to the browser without proper sanitization, enabling the execution of arbitrary script code in the user's browser context. This vulnerability specifically aligns with CWE-79, which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding.
The operational impact of this vulnerability extends beyond simple script execution, as it can potentially enable attackers to access sensitive browser-based information and manipulate the administrative interface. An attacker who successfully exploits this vulnerability could gain unauthorized access to the web-based management interface, potentially leading to full administrative control of the WSA device. The reflected nature of the XSS attack means that the malicious payload is not stored on the server but rather reflected back to the user's browser from the web application's response, making it particularly challenging to detect and prevent through traditional security measures.
The attack requires social engineering to succeed, as users must be convinced to click on the malicious link crafted by the attacker. This human factor component makes the vulnerability particularly dangerous in environments where users may not be adequately trained in recognizing phishing attempts or malicious links. The vulnerability affects the web-based management interface specifically, which means that the attack vector is limited to users who access the device's administrative console through a web browser rather than through command-line or other interfaces. Organizations implementing Cisco WSA devices face significant risk if proper network segmentation and access controls are not in place to limit exposure of the management interface to untrusted networks.
Mitigation strategies for CVE-2018-0093 should include immediate patching of affected devices with Cisco's security updates addressing the input validation flaw. Network administrators should also implement strict access controls limiting access to the WSA management interface to trusted IP addresses and implement network segmentation to prevent unauthorized access. Additionally, organizations should deploy web application firewalls and implement proper input validation and output encoding mechanisms throughout their web applications. The vulnerability's classification under ATT&CK technique T1059.007 for script execution through web interfaces highlights the need for comprehensive security monitoring and incident response procedures. Regular security assessments and user awareness training should be implemented to reduce the risk of successful social engineering attacks that exploit this vulnerability, as the attack's success depends heavily on user interaction with malicious content.