CVE-2017-6764 in ASA
Summary
by MITRE
A vulnerability in the web-based management interface of Cisco Adaptive Security Appliance (ASA) 9.5(1) could allow an authenticated, remote attacker to conduct a 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: CSCvd82064.
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Analysis
by VulDB Data Team • 01/07/2021
The vulnerability identified as CVE-2017-6764 affects the web-based management interface of Cisco Adaptive Security Appliance (ASA) version 9.5(1), representing a critical cross-site scripting flaw that enables authenticated remote attackers to compromise user sessions. This vulnerability stems from inadequate input validation mechanisms within the web interface, specifically failing to properly sanitize user-supplied data before processing and rendering it back to the browser. The flaw exists in the ASA's web management console which serves as the primary administrative interface for configuring and monitoring the security appliance, making it a prime target for exploitation attempts. The vulnerability is particularly concerning as it requires minimal user interaction to exploit, relying solely on social engineering to deliver malicious payloads through crafted links that appear legitimate to unsuspecting administrators.
The technical implementation of this XSS vulnerability occurs when the web interface processes user input without adequate sanitization, allowing malicious scripts to be injected into the application's response. When an authenticated user clicks on a maliciously crafted link containing the XSS payload, the script executes within the context of the user's browser session, potentially compromising the integrity of the management interface. This type of vulnerability falls under CWE-79 which specifically addresses Cross-site Scripting flaws in web applications, and aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter. The vulnerability permits attackers to execute arbitrary code within the browser context, potentially enabling them to steal session cookies, redirect users to malicious sites, or access sensitive information that would otherwise be protected by the web interface's authentication mechanisms.
The operational impact of this vulnerability extends beyond simple script execution as it creates a persistent threat vector for attackers seeking to maintain access to the ASA management interface. Successful exploitation allows attackers to potentially escalate privileges, modify security policies, or exfiltrate sensitive configuration data from the network security appliance. The authenticated nature of the vulnerability means that attackers do not need to compromise the device through other means, as they can leverage the legitimate administrative interface to gain unauthorized access to the system. This makes the attack surface significantly broader since any user with valid credentials could be targeted, and the attack requires only a single click from the victim to succeed. The vulnerability also enables data theft and manipulation of the security appliance's configuration, potentially allowing attackers to bypass network security controls or establish persistent access points within the network infrastructure.
Mitigation strategies for CVE-2017-6764 should prioritize immediate patching of affected ASA devices to the latest available software versions that contain the necessary input validation fixes. Cisco released security advisories and patches addressing this vulnerability, and administrators should implement these updates as soon as possible to eliminate the XSS risk. Network segmentation and monitoring should be enhanced to detect unusual activity patterns that might indicate exploitation attempts, including monitoring for suspicious URL parameters or unusual administrative access patterns. Additional protective measures include implementing web application firewalls to filter malicious requests, establishing strict access controls for the web management interface, and conducting regular security awareness training for administrators to recognize potential social engineering attempts. The vulnerability also underscores the importance of maintaining up-to-date security patches and following secure coding practices to prevent similar input validation issues in other network security appliances and management interfaces.