CVE-2022-31065 in BigBlueButton
Summary
by MITRE • 06/28/2022
BigBlueButton is an open source web conferencing system. In affected versions an attacker can embed malicious JS in their username and have it executed on the victim's client. When a user receives a private chat from the attacker (whose username contains malicious JavaScript), the script gets executed. Additionally when the victim receives a notification that the attacker has left the session. This issue has been patched in version 2.4.8 and 2.5.0. There are no known workarounds for this issue.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/16/2022
This vulnerability exists within BigBlueButton, an open source web conferencing platform that facilitates online meetings and collaboration. The flaw represents a critical cross-site scripting vulnerability that allows attackers to inject malicious javascript code into user identifiers. The vulnerability stems from insufficient input validation and output encoding within the application's username handling mechanisms, creating a pathway for persistent script injection attacks. The issue affects versions prior to 2.4.8 and 2.5.0, leaving organizations using these older releases exposed to potential exploitation.
The technical implementation of this vulnerability occurs through the manipulation of username fields within the chat and session notification systems. When an attacker registers with a malicious javascript payload embedded in their username, this code becomes executable when other users interact with the system. Specifically, the vulnerability triggers during private chat interactions where the attacker's malicious username is rendered in the victim's browser context, and also during session leave notifications. This represents a classic persistent cross-site scripting flaw where the malicious code is stored server-side and executed client-side when legitimate users view the compromised content. The vulnerability aligns with CWE-79 which classifies improper neutralization of input during web output, and specifically relates to CWE-80 which addresses cross-site scripting in user input.
The operational impact of this vulnerability is severe as it enables attackers to execute arbitrary javascript code within the context of victims' browsers, potentially leading to session hijacking, data exfiltration, and further compromise of the conferencing environment. Attackers can leverage this vulnerability to steal session cookies, capture keystrokes, manipulate the user interface, or redirect victims to malicious websites. The persistent nature of the vulnerability means that once exploited, the malicious code continues to execute whenever affected users interact with the system, creating ongoing security risks. This vulnerability can be particularly dangerous in educational or corporate settings where sensitive meetings and discussions occur, as it provides attackers with access to confidential information shared during conferences. The attack vector is relatively simple to exploit since it only requires the attacker to register with a malicious username and initiate chat or session leave notifications.
Organizations should immediately upgrade to BigBlueButton versions 2.4.8 or 2.5.0 to remediate this vulnerability, as no effective workarounds exist for this particular flaw. The patch addresses the root cause by implementing proper input sanitization and output encoding mechanisms for all user-provided identifiers. Security teams should also implement network monitoring to detect potential exploitation attempts and consider deploying web application firewalls to provide additional defense-in-depth. Regular security assessments of the conferencing platform should be conducted to identify similar vulnerabilities, and user education regarding suspicious chat interactions should be emphasized. The vulnerability demonstrates the importance of proper input validation in web applications and aligns with ATT&CK technique T1566 which covers credential access through social engineering and malicious code injection. Organizations should also review their incident response procedures to ensure they can effectively respond to potential exploitation of this vulnerability in their environments.