CVE-2016-2820 in Firefox
Summary
by MITRE
The Firefox Health Reports (aka FHR or about:healthreport) feature in Mozilla Firefox before 46.0 does not properly restrict the origin of events, which makes it easier for remote attackers to modify sharing preferences by leveraging access to the remote-report IFRAME element.
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Analysis
by VulDB Data Team • 07/27/2022
The vulnerability described in CVE-2016-2820 affects Mozilla Firefox versions prior to 46.0, specifically within the Firefox Health Reports feature also known as FHR or the about:healthreport interface. This feature collects and reports user health data to Mozilla for diagnostic purposes, including information about browser performance, add-on usage, and system configuration. The flaw resides in the implementation of the remote-report IFRAME element which is used to display health report data from Mozilla's servers. The vulnerability stems from insufficient origin validation mechanisms that fail to properly restrict which domains can send events to the health reporting system, creating a potential attack vector for malicious actors.
The technical nature of this vulnerability involves a lack of proper cross-origin resource sharing (CORS) validation within Firefox's health reporting framework. When the browser processes health report data through the about:healthreport interface, it fails to validate the origin of events sent through the remote-report IFRAME element. This allows remote attackers with access to a malicious website to manipulate the sharing preferences of Firefox's health reporting feature. The flaw essentially enables attackers to inject malicious data or modify existing health report configurations, potentially leading to unauthorized data collection or false reporting of browser health metrics. This issue is classified as a weakness in input validation and origin verification, aligning with CWE-20, which covers improper input validation, and CWE-345, which addresses insufficient verification of data integrity.
The operational impact of this vulnerability extends beyond simple data manipulation, as it could enable attackers to compromise the integrity of Firefox's health reporting system. Attackers could potentially alter sharing preferences to either disable health reporting entirely or force the transmission of malicious data to third-party servers. The vulnerability is particularly concerning because it operates at the browser level, affecting all users who have Firefox Health Reports enabled, and could be exploited through standard web browsing activities. This weakness could be leveraged in combination with other attacks to create more sophisticated social engineering campaigns or to gather information about browser configurations that might be useful for targeting other vulnerabilities. The attack surface is broad since any website could potentially exploit this flaw, making it a significant concern for user privacy and data integrity.
Security professionals should prioritize updating Firefox installations to version 46.0 or later to mitigate this vulnerability, as Mozilla released a patch specifically addressing the improper origin validation in the health reporting feature. The recommended mitigation strategy involves ensuring all Firefox installations are updated to the latest version, which includes proper origin validation for the remote-report IFRAME element. Organizations should also consider implementing network monitoring to detect unusual health report data transmission patterns that might indicate exploitation attempts. Additionally, user education about the importance of keeping browsers updated and avoiding untrusted websites can help reduce the risk of exploitation. This vulnerability demonstrates the importance of proper input validation and origin checking in web browser components, particularly those that handle user data and privacy-sensitive information. The issue aligns with ATT&CK technique T1566, which covers spearphishing through social engineering, as attackers could potentially use this vulnerability to gather intelligence about target systems before launching more sophisticated attacks.