CVE-2019-1792 in Umbrella API
Summary
by MITRE
A vulnerability in the URL block page of Cisco Umbrella could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a user in a network protected by Umbrella. The vulnerability is due to insufficient validation of input parameters passed to that page. An attacker could exploit this vulnerability by persuading a user of the interface to click a maliciously crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or access sensitive browser-based information. This vulnerability has been fixed in the current version of Cisco Umbrella. Cisco Umbrella is a cloud service.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/04/2023
The vulnerability identified as CVE-2019-1792 resides within the URL block page functionality of Cisco Umbrella, a cloud-based security service designed to protect networks from malicious web traffic. This security flaw represents a critical cross-site scripting vulnerability that undermines the integrity of the user interface protection mechanisms. The vulnerability specifically affects the validation of input parameters within the URL block page, creating an attack surface where malicious actors can manipulate the system through crafted web requests. Cisco Umbrella operates as a cloud-delivered security solution that filters internet traffic before it reaches end-user devices, making this vulnerability particularly concerning as it targets the very interface designed to protect users from web-based threats.
The technical exploitation of CVE-2019-1792 occurs when an unauthenticated attacker crafts a malicious link that, when clicked by a user within an Umbrella-protected network, triggers the XSS payload within the URL block page. This vulnerability stems from inadequate input sanitization and parameter validation within the web interface components of the Cisco Umbrella service. The insufficient validation allows malicious data to be processed and rendered without proper security checks, enabling attackers to inject arbitrary script code that executes within the user's browser context. The vulnerability's classification aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications. Attackers can leverage this weakness to execute malicious scripts that may steal session cookies, redirect users to malicious sites, or extract sensitive information from the browser environment.
The operational impact of this vulnerability extends beyond simple script execution, as it fundamentally compromises the trust model of the Cisco Umbrella protection system. When successfully exploited, the vulnerability allows attackers to access sensitive browser-based information and potentially execute arbitrary code within the user's browser session. This creates a scenario where the security protection mechanism itself becomes a vector for attack, undermining the very purpose of the service. The attack requires user interaction through a malicious link, but once triggered, it can provide attackers with persistent access to the user's browser session. This vulnerability demonstrates a critical failure in the security architecture of the URL block page, where the interface designed to protect users from web threats becomes a potential attack vector. The exploitation can lead to session hijacking, data theft, and further lateral movement within the network, as the compromised browser session may contain authentication tokens and other sensitive information.
Mitigation strategies for CVE-2019-1792 focus on the immediate implementation of the vendor-provided security patches and updates that address the input validation deficiencies within the Cisco Umbrella service. Organizations should ensure that all instances of Cisco Umbrella are updated to versions that contain the necessary fixes, as the vulnerability has been resolved in current versions of the service. Network administrators should also implement additional monitoring and logging to detect potential exploitation attempts, particularly around URL block page interactions and suspicious user activities. The remediation process should include verification that the input validation mechanisms are properly functioning and that all user-supplied data is appropriately sanitized before processing. Security teams should conduct regular assessments of the Umbrella service configuration to ensure that no additional attack vectors remain open. This vulnerability serves as a reminder of the importance of robust input validation and the principle of least privilege in web application security, as outlined in the ATT&CK framework's web application attack patterns. Organizations should also consider implementing additional network-level protections such as web application firewalls and content security policies to provide defense-in-depth against similar vulnerabilities.