CVE-2021-23986 is a medium-severity vulnerability affecting Mozilla Firefox versions prior to 87. This vulnerability allows a malicious extension with the 'search' permission to install a new search engine whose favicon references a cross-origin URL. As a result, the extension can read the response to this cross-origin request, enabling a bypass of the same-origin policy, which should restrict such cross-origin permissions.
The attack vector is network-based, and while the complexity is low, user interaction is required, making it crucial for users to exercise caution when installing extensions. The potential confidentiality impact is high, but integrity and availability impacts remain unchanged.
Risk to organizations includes exposure of sensitive information from local-network resources or those performing IP-based authentication. Given the nature of this vulnerability, organizations should prioritize patching immediately.
As of now, there is no known exploit for this vulnerability, but organizations must remain vigilant and ensure they are using the latest version of Firefox to mitigate risks.
The vulnerability was published on March 31, 2021, and has been modified since its disclosure. Organizations are encouraged to stay informed about updates related to this vulnerability.
Vulnerability Details
A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication.
This vulnerability affects Firefox versions below 87.
Technical Analysis
Root cause analysis indicates that the vulnerability arises from improper handling of cross-origin permissions by the extension framework in Firefox. Attackers may leverage this flaw to read sensitive data from local networks, exploiting the trust relationships established by the browser's extension system.
The attack vector is network-based, requiring a user to install a malicious extension that has been granted the 'search' permission. The complexity of the attack is low since there is no need for elevated privileges or user interaction beyond the initial installation.
The confidentiality impact is high, as it can lead to exposure of sensitive information, whereas there is no integrity or availability impact.
Risk & Impact Analysis
Organizations utilizing Firefox should recognize the potential risks associated with CVE-2021-23986. The real-world deployment risk is significant, particularly for those relying on extensions for functionality. With the potential for sensitive data exposure, the urgency for remediation is categorized as high.
The blast radius of this vulnerability encompasses users who have installed vulnerable extensions, thereby impacting data confidentiality across potentially multiple organizations. Given that the CVSS score is 6.5, organizations should address this vulnerability in their priority patch cycle.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch (Firefox < 87) are affected by this vulnerability. Organizations should ensure they update to the latest version to mitigate potential risks.
Mitigation & Remediation
Organizations should prioritize updating Firefox to version 87 or later to remediate this vulnerability. It is crucial to regularly audit and review installed extensions, removing any that are unverified or no longer needed.
For additional security, organizations may consider implementing network controls to restrict access to sensitive resources and monitoring for unusual extension behavior.
For further guidance on securing your applications, organizations can refer to the application security assessment services.
Detection Guidance
Organizations should monitor logs for indicators of malicious extension installations or access attempts to sensitive resources. Behavioral anomalies in user activity may also signal attempts to exploit this vulnerability.
Regularly reviewing network traffic for unusual patterns can help identify unauthorized access attempts or data exfiltration efforts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-23986 highlights the need for vigilance in managing browser extensions. As attackers continue to exploit trust relationships, security teams must implement stringent controls over extension permissions and regularly assess the security posture of third-party components.
This vulnerability represents a pattern of similar risks that have emerged in the browser ecosystem, emphasizing the importance of user awareness and extension management.
Organizations can enhance their defenses against such vulnerabilities by investing in comprehensive security testing methodologies, such as penetration testing and adopting a proactive approach to vulnerability management.
Security teams should also consider the implications of such vulnerabilities on their overall security strategy and ensure that they are prepared to respond swiftly to similar threats in the future.
For further insights on penetration testing best practices, organizations can refer to the penetration testing methodology guide.
Additionally, organizations may benefit from reviewing their security policies in light of this vulnerability to ensure they address potential risks posed by browser extensions.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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