CVE-2017-5413 in Firefox
Summary
by MITRE
A segmentation fault can occur during some bidirectional layout operations. This vulnerability affects Firefox < 52 and Thunderbird < 52.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/18/2020
The vulnerability identified as CVE-2017-5413 represents a critical memory corruption issue affecting the rendering engine of Mozilla Firefox and Thunderbird applications. This segmentation fault occurs during bidirectional layout operations, which are essential components for handling text directionality in internationalized applications. The flaw specifically manifests when the browser processes content containing complex text layouts that require bidirectional rendering, a common requirement for supporting languages that read right-to-left such as Arabic and Hebrew alongside left-to-right languages. The vulnerability resides within the Gecko layout engine that powers these applications, making it particularly concerning given the widespread use of Firefox and Thunderbird across global user bases.
Technical analysis reveals that this vulnerability stems from improper memory management during the processing of bidirectional text elements within the browser's rendering pipeline. When the application encounters specific combinations of text elements requiring bidirectional layout calculations, the memory allocation and deallocation mechanisms fail to properly handle the complex interactions between different text directionality contexts. This results in a segmentation fault that causes the application to crash unexpectedly, potentially leading to denial of service conditions. The flaw is classified as a memory safety issue and aligns with CWE-125, which addresses out-of-bounds read conditions, and CWE-119, which covers weak buffer access protections. The vulnerability demonstrates characteristics consistent with heap-based buffer overflows or use-after-free conditions that can occur when complex layout algorithms interact with improperly validated input data.
The operational impact of this vulnerability extends beyond simple application crashes, as it represents a potential vector for more sophisticated attacks. While the immediate effect is a segmentation fault leading to application termination, the underlying memory corruption issues could theoretically be exploited to execute arbitrary code on affected systems. This makes the vulnerability particularly dangerous in environments where these applications are used for sensitive operations or where users may be targeted through phishing campaigns. The vulnerability affects versions prior to Firefox 52 and Thunderbird 52, indicating that users running these older versions face significant risk. The bidirectional text processing functionality is commonly used in web applications, making the attack surface broader than initially apparent, and the vulnerability can be triggered through various means including web pages containing specific text formatting or email messages with complex internationalized content.
Mitigation strategies for CVE-2017-5413 focus primarily on immediate software updates and patches provided by Mozilla. Users should upgrade to Firefox version 52 or later and Thunderbird version 52 or later to eliminate the vulnerability. Organizations should implement automated patch management systems to ensure all affected applications are updated promptly across their networks. Additional defensive measures include implementing web filtering solutions that can block potentially malicious content, configuring browser security settings to limit the execution of untrusted content, and monitoring for unusual application behavior that might indicate exploitation attempts. The vulnerability highlights the importance of regular security updates and proper memory management practices in complex software systems. From an ATT&CK framework perspective, this vulnerability could be categorized under T1059 for command and scripting interpreter usage and T1203 for exploitation for privilege escalation, though the primary threat vector is the initial exploitation leading to application compromise. Security teams should also consider implementing network-based intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability, as the segmentation fault behavior may be detectable through unusual network traffic patterns or system behavior anomalies.