CVE-2018-5109 in Firefox
Summary
by MITRE
An audio capture session can started under an incorrect origin from the site making the capture request. Users are still prompted to allow the request but the prompt can display the wrong origin, leading to user confusion about which site is making the request to capture an audio stream. This vulnerability affects Firefox < 58.
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Analysis
by VulDB Data Team • 02/01/2021
This vulnerability represents a significant user interface deception issue in Firefox browsers prior to version 58, where the audio capture permission prompt fails to accurately display the originating website. The flaw stems from improper origin validation during the audio capture session initiation process, allowing malicious actors to exploit user trust by displaying misleading origin information. This misrepresentation occurs specifically during the permission prompt phase when users are asked to grant access to their microphone, creating a scenario where users may unknowingly authorize audio capture from a fraudulent domain rather than the legitimate site requesting access.
The technical implementation of this vulnerability involves the browser's permission handling system failing to properly validate and display the correct origin context when initiating audio capture sessions. The underlying mechanism relies on the Web Audio API and MediaDevices.getUserMedia() interface which should enforce strict origin checking but instead permits incorrect origin display in permission prompts. This represents a violation of proper access control mechanisms and user consent validation principles, as outlined in CWE-676. The vulnerability specifically affects the browser's security UI components that are responsible for presenting permission requests to users, creating a mismatch between the actual requesting origin and the displayed origin information.
The operational impact of this vulnerability extends beyond simple user confusion to potentially enable sophisticated phishing attacks and social engineering campaigns. Attackers can exploit this weakness to make users believe they are granting audio access to a trusted site while actually capturing audio from a malicious domain. This creates opportunities for unauthorized surveillance and data collection, particularly in environments where users might be prompted to grant microphone access to sites they trust but which are actually controlled by attackers. The vulnerability aligns with ATT&CK technique T1566 which covers social engineering tactics involving deceptive prompts and user interface manipulation.
Users experiencing this vulnerability may grant audio capture permissions without proper understanding of which site is actually making the request, potentially leading to unauthorized surveillance and privacy violations. The attack surface is particularly concerning in enterprise environments where users might be prompted to grant access to sensitive audio streams from seemingly legitimate internal applications. Organizations should consider this vulnerability when implementing security policies around microphone access and user consent management, as it undermines the fundamental security principle of informed consent in web applications.
Mitigation strategies should focus on immediate browser updates to version 58 or later where the vulnerability has been patched. System administrators should implement monitoring for audio capture requests and user consent patterns to detect potential exploitation attempts. Additional protective measures include user education about verifying origin information in permission prompts, implementing browser security policies that restrict audio capture capabilities, and establishing clear guidelines for when and how microphone access should be granted. The fix implemented by Mozilla addresses the core origin validation issue in the permission prompt system, ensuring that the displayed origin information accurately reflects the requesting website. Organizations should also consider deploying web application firewalls and browser security extensions that can provide additional layers of protection against such UI deception attacks.