CVE-2021-1311 in WebEx Meetings
Summary
by MITRE • 01/14/2021
A vulnerability in the reclaim host role feature of Cisco Webex Meetings and Cisco Webex Meetings Server could allow an authenticated, remote attacker to take over the host role during a meeting. This vulnerability is due to a lack of protection against brute forcing of the host key. An attacker could exploit this vulnerability by sending crafted requests to a vulnerable Cisco Webex Meetings or Webex Meetings Server site. A successful exploit would require the attacker to have access to join a Webex meeting, including applicable meeting join links and passwords. A successful exploit could allow the attacker to acquire or take over the host role for a meeting.
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Analysis
by VulDB Data Team • 02/14/2021
The vulnerability identified as CVE-2021-1311 represents a critical security flaw within Cisco Webex Meetings and Cisco Webex Meetings Server implementations that specifically targets the host role management functionality. This weakness resides in the reclaim host role feature, which is designed to allow authorized participants to assume host responsibilities during online meetings. The flaw fundamentally stems from insufficient protection mechanisms against brute force attacks targeting the host key authentication system, creating a significant attack vector for malicious actors who possess basic meeting access credentials.
The technical exploitation of this vulnerability occurs through carefully crafted network requests that attempt to guess or iterate through valid host keys associated with active meetings. The underlying issue manifests as a lack of rate limiting, account lockout mechanisms, or other protective measures that would typically prevent automated brute force attempts. Attackers can leverage this weakness by joining legitimate meetings using valid meeting links and passwords, then systematically attempting to acquire host privileges through repeated authentication attempts. This vulnerability specifically affects the authentication flow that validates host keys, where the system fails to implement adequate protections against automated attack patterns that could lead to unauthorized privilege escalation.
From an operational impact perspective, this vulnerability creates a severe risk for organizations relying on Cisco Webex for business communications, as it allows attackers to assume complete control over meetings they can access. The successful exploitation enables unauthorized individuals to manipulate meeting settings, control participant access, share or restrict content, and potentially access sensitive information discussed during the meeting. This represents a significant compromise of meeting security and could lead to data breaches, unauthorized communications, and disruption of business operations. The vulnerability essentially undermines the fundamental security model of meeting host authentication, making it possible for attackers to gain administrative control over meetings without proper authorization.
The weakness aligns with CWE-307, which addresses "Improper Restriction of Excessive Authentication Attempts" and corresponds to ATT&CK technique T1078.101, "Valid Accounts: Default Accounts" and T1566.001, "Phishing: Spearphishing Attachment". Organizations should implement immediate mitigations including enabling rate limiting on authentication requests, implementing account lockout policies after failed authentication attempts, and monitoring for unusual patterns of host key access attempts. Cisco has released patches and updates to address this vulnerability, and organizations should ensure all systems are updated to the latest secure versions. Network segmentation and monitoring solutions should be deployed to detect anomalous authentication patterns that could indicate exploitation attempts. Additionally, administrators should review and restrict meeting join permissions, implement stronger authentication mechanisms, and conduct regular security assessments to identify and remediate similar vulnerabilities in their communication infrastructure.