CVE-2014-1559 in Firefox
Summary
by MITRE
Mozilla Firefox before 31.0 and Thunderbird before 31.0 allow remote attackers to cause a denial of service (X.509 certificate parsing outage) via a crafted certificate that does not use UTF-8 character encoding in a required context, a different vulnerability than CVE-2014-1558.
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Analysis
by VulDB Data Team • 02/09/2022
The vulnerability identified as CVE-2014-1559 represents a critical flaw in Mozilla Firefox versions prior to 31.0 and Thunderbird versions before 31.0 that specifically targets the X.509 certificate parsing mechanism within these applications. This issue stems from the improper handling of character encoding during certificate validation processes, creating a potential denial of service condition that can be exploited remotely by attackers. The flaw occurs when certificates contain non-UTF-8 encoded characters in contexts where UTF-8 is required, demonstrating a fundamental weakness in the certificate validation infrastructure that affects the core security functionality of these email and web browsers.
The technical implementation of this vulnerability exploits the certificate parsing logic by presenting certificates with malformed character encoding that violates the expected UTF-8 standards required for X.509 certificate fields. When Firefox or Thunderbird attempt to validate such certificates, the parsing routines fail to properly handle the non-conforming encoding, leading to application instability and potential crashes. This behavior falls under CWE-707, which addresses improper use of potentially dangerous API functions, specifically in the context of certificate validation and parsing operations. The vulnerability demonstrates how seemingly minor encoding issues can cascade into significant security impacts when they occur in critical validation paths.
From an operational perspective, this vulnerability creates a substantial risk for users who may encounter maliciously crafted certificates during normal browsing or email operations. The remote exploitation capability means that attackers can trigger the denial of service condition without requiring local access or user interaction beyond normal certificate exchange processes. This makes the vulnerability particularly dangerous in environments where users may encounter certificates from untrusted sources, such as during web browsing or email communication with external parties. The impact extends beyond simple service disruption to potentially compromising the security posture of affected systems when certificate validation fails.
The mitigation strategy for CVE-2014-1559 involves immediate deployment of updated versions of Firefox and Thunderbird where the certificate parsing logic has been corrected to properly handle various character encodings. Organizations should prioritize patch management processes to ensure all affected systems receive updates promptly. Additionally, security teams should monitor for potential exploitation attempts and implement network-based detection measures that can identify malformed certificate traffic patterns. This vulnerability aligns with ATT&CK technique T1059, which covers the use of system services and applications for malicious purposes, as the exploitation leverages legitimate certificate validation mechanisms to achieve denial of service effects. The remediation process should also include comprehensive testing of certificate handling capabilities to ensure that similar encoding issues do not exist in other areas of the application infrastructure.