CVE-2022-29169 : Exploit Details and Defense Strategies
Learn about CVE-2022-29169 impacting BigBlueButton. Vulnerable versions, impact, and mitigation steps provided. Update to secure versions 2.3.19, 2.4.7, or 2.5.0-beta.2.
BigBlueButton versions starting with 2.2 and prior to 2.3.19, 2.4.7, and 2.5.0-beta.2 are susceptible to regular expression denial of service (ReDoS) attacks. This vulnerability can be exploited to cause denial of service for the bbb-html5 service.
Understanding CVE-2022-20657
Regular Expression Denial of Service (ReDoS) vulnerability in the html5client/useragent endpoint of BigBlueButton
What is CVE-2022-20657?
BigBlueButton, an open-source web conferencing system, is impacted by a ReDoS vulnerability in versions 2.2 to 2.3.19, 2.4.7, and 2.5.0-beta.2. Attackers can utilize specific RegularExpressions to trigger denial of service by exploiting the useragent library.
The Impact of CVE-2022-20657
The vulnerability poses a high availability impact, allowing attackers to disrupt the bbb-html5 service by causing denial of service.
Technical Details of CVE-2022-20657
Details on the vulnerability in BigBlueButton
Vulnerability Description
The issue arises from improper input validation in handling User-Agent headers, enabling attackers to abuse regex processing and deliver ReDoS payloads using 'SmartWatch'.
Affected Systems and Versions
Versions >= 2.2, < 2.3.19 and >= 2.4.0, < 2.4.7, as well as >= 2.5-alpha-1, < 2.5.0-beta.2 are vulnerable to this ReDoS attack.
Exploitation Mechanism
Attackers exploit the Regular Expression handling in the useragent library to trigger denial of service, impacting the bbb-html5 service.
Mitigation and Prevention
Protecting your systems from CVE-2022-20657
Immediate Steps to Take
As a workaround, disable NginX from forwarding requests to the handler following the guidelines provided in the GitHub Security Advisory.
Long-Term Security Practices
Implement proper input validation mechanisms for handling User-Agent headers and ensure regex processing is secure to mitigate ReDoS attacks.
Patching and Updates
Update BigBlueButton to versions 2.3.19, 2.4.7, or 2.5.0-beta.2 to address the vulnerability and prevent potential denial of service attacks.