CVE-2023-20133 in Webex Meetings
Summary
by MITRE • 07/07/2023
A vulnerability in the web interface of Cisco Webex Meetings could allow an authenticated, remote attacker to conduct a stored cross-site scripting (XSS) attack against a user of the interface. This vulnerability exists because of insufficient validation of user-supplied input in Webex Events (classic) programs, email templates, and survey questions. An attacker could exploit this vulnerability by persuading a user to click a malicious 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.
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Analysis
by VulDB Data Team • 07/23/2023
This vulnerability resides within the web interface of Cisco Webex Meetings, specifically targeting the classic Webex Events functionality that handles program management, email template creation, and survey question development. The flaw represents a classic stored cross-site scripting vulnerability that operates through the manipulation of user-supplied input data within these administrative components. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize or escape user-provided content before it is stored and subsequently rendered within the web interface. Attackers can exploit this weakness by crafting malicious payloads within the vulnerable fields, which then get stored on the server and executed when legitimate users interact with the affected interface elements. The attack vector requires authentication to access the web interface, making it a privilege escalation vulnerability rather than a purely remote threat. The security implications extend beyond simple script execution to potentially enable data theft, session hijacking, and further lateral movement within the network environment.
The technical nature of this vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and it demonstrates the classic pattern of stored XSS where malicious input is permanently stored on the server and later executed in the context of other users' browsers. From an operational perspective, this vulnerability creates a persistent threat vector that can be exploited repeatedly without requiring continuous user interaction beyond the initial payload injection. The attack scenario typically involves an attacker identifying a target user with access to the Webex Events administrative interface, crafting malicious content within the vulnerable fields, and then persuading the target user to click on a malicious link or interact with the compromised interface elements. The execution context provides attackers with the ability to execute arbitrary JavaScript code within the victim's browser session, potentially allowing for complete session compromise, data exfiltration, or redirection to malicious sites. This vulnerability represents a significant risk to organizations that rely heavily on Webex for meetings and collaboration, as it can be exploited to gain unauthorized access to sensitive meeting data, user information, and potentially escalate privileges within the application.
The impact of successful exploitation extends beyond immediate script execution to encompass broader security implications including potential privilege escalation, data theft, and service disruption. Organizations utilizing Webex Events for critical business operations face heightened risk as attackers can manipulate survey questions, email templates, and program configurations to inject malicious payloads that persist across multiple user sessions. The vulnerability's persistence means that once exploited, the malicious code continues to execute against any user who accesses the affected interface elements until the malicious content is removed or the system is patched. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communication, credential access, and privilege escalation through web application exploitation. The threat actor can leverage this vulnerability to establish persistent access to the Webex environment, potentially enabling them to monitor meetings, access sensitive documents, or manipulate meeting configurations. Organizations should implement comprehensive monitoring for suspicious activities within the Webex interface, particularly around modifications to email templates, survey questions, and program content. The vulnerability underscores the importance of robust input validation, output encoding, and regular security assessments of web applications, particularly those handling user-generated content in collaborative environments.