CVE-2016-1947 in Firefox
Summary
by MITRE
Mozilla Firefox 43.x mishandles attempts to connect to the Application Reputation service, which makes it easier for remote attackers to trigger an unintended download by leveraging the absence of reputation data.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2016-1947 resides within Mozilla Firefox version 43.x and pertains to improper handling of connections to the Application Reputation service. This flaw creates a security risk where remote attackers can exploit the absence of proper reputation data validation to trigger unintended downloads. The issue stems from how Firefox processes requests to the application reputation service, specifically when the service fails to provide expected reputation information. When the Application Reputation service does not return proper data, Firefox should ideally refuse to proceed with the download or implement additional verification mechanisms. However, the vulnerability allows the browser to proceed with downloads even when reputation data is missing or incomplete, creating an attack surface that adversaries can leverage.
The technical nature of this vulnerability aligns with CWE-200, which addresses information exposure, and CWE-345, which covers insufficient verification of data authenticity. The flaw represents a failure in input validation and verification processes within Firefox's download handling mechanism. When the Application Reputation service is unavailable or returns malformed data, the browser's security controls fail to properly validate the download request, potentially allowing malicious content to be executed or downloaded without proper security checks. This behavior creates a dangerous precedent where users might unknowingly download harmful software or content that would normally be blocked based on reputation assessments.
The operational impact of CVE-2016-1947 extends beyond simple download manipulation, as it can facilitate various attack vectors including drive-by downloads, malicious software distribution, and phishing campaigns. Attackers can exploit this vulnerability by crafting specially designed web pages that trigger the flawed behavior in Firefox, leading to unauthorized downloads that bypass typical security controls. The vulnerability is particularly concerning because it operates at the browser level and affects user trust in the security mechanisms that Firefox provides. Users may be unaware that their downloads are being processed without proper reputation verification, creating a false sense of security while actual threats are being introduced into their systems.
This vulnerability demonstrates a gap in Firefox's security architecture related to service dependency management and error handling. The browser's failure to implement proper fallback mechanisms when the Application Reputation service is unavailable creates a security weakness that can be systematically exploited. From an ATT&CK perspective, this vulnerability maps to techniques involving execution through system services and command and control communications, as it enables attackers to establish unauthorized download channels. The threat actors can leverage this weakness to deliver malware payloads or phishing content that would otherwise be rejected by reputation-based security controls. Organizations should consider this vulnerability as part of their broader security posture assessment, particularly in environments where Firefox is used as a primary browser and where reputation-based security controls are relied upon for threat prevention.
Mitigation strategies for CVE-2016-1947 should focus on immediate patching of affected Firefox versions to the latest stable releases that contain fixes for this vulnerability. Users should be educated about the risks associated with downloading content from untrusted sources and the importance of keeping their browsers updated. Network administrators should implement additional monitoring for unusual download patterns that might indicate exploitation attempts. Security teams should review their browser security policies to ensure that proper controls are in place for managing service dependencies and error conditions. The vulnerability also highlights the need for robust error handling and fallback mechanisms in security-critical applications, emphasizing that systems should fail securely when dependent services are unavailable rather than proceeding with potentially dangerous operations.