CVE-2021-38494 in Firefox
Summary
by MITRE • 11/03/2021
Mozilla developers reported memory safety bugs present in Firefox 91. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 92.
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Analysis
by VulDB Data Team • 11/06/2021
Mozilla Firefox version 91 contained multiple memory safety vulnerabilities that could potentially lead to arbitrary code execution, as identified through comprehensive security assessments conducted by the Firefox development team. These memory safety bugs represent critical flaws in the browser's memory management systems that could be exploited by attackers to compromise system integrity. The vulnerabilities were discovered during routine security auditing and code review processes, highlighting the importance of continuous security monitoring in complex software applications. The presence of memory corruption evidence suggests that these flaws could enable attackers to manipulate memory structures and execute malicious code with elevated privileges. The vulnerability affects all Firefox versions prior to 92, making it a significant concern for users who have not yet updated their browsers. This type of memory safety issue typically arises from improper handling of memory allocation, deallocation, or pointer operations within the browser's rendering engine and JavaScript engine components. The potential for arbitrary code execution through these memory corruption flaws represents a severe threat to user security and system integrity.
The technical nature of these memory safety bugs aligns with common cybersecurity vulnerabilities that fall under the CWE (Common Weakness Enumeration) category of memory safety issues, specifically CWE-119 and CWE-125 which relate to improper access to memory locations and out-of-bounds read/write operations. These vulnerabilities demonstrate how seemingly minor memory handling errors can create substantial security risks when exploited in the context of a complex browser environment. The browser's JavaScript engine and rendering components are particularly susceptible to such issues due to the extensive memory operations required for processing web content. Attackers could potentially leverage these flaws by crafting malicious web pages or content that triggers the vulnerable code paths during normal browser operation. The exploitation process would likely involve manipulating memory structures to overwrite critical data or function pointers, ultimately leading to code execution. This type of vulnerability is particularly dangerous because it can be triggered remotely through web browsing activities, requiring no local user interaction beyond visiting malicious websites.
The operational impact of CVE-2021-38494 extends beyond individual user security to encompass broader organizational risks, particularly for enterprises that rely on Firefox for business operations. Users who remain on Firefox version 91 face significant exposure to potential attacks that could result in data breaches, system compromise, or unauthorized access to sensitive information. The vulnerability's remote exploitability means that attackers can target users without requiring physical access to their systems, making it particularly concerning for organizations with distributed workforces or those operating in high-risk threat environments. Security teams must prioritize the immediate deployment of Firefox 92 updates across all affected systems to mitigate this risk. The presence of these memory safety issues in a widely-used browser like Firefox creates a substantial attack surface that threat actors actively monitor and exploit. Organizations should implement comprehensive patch management processes to ensure rapid deployment of security updates and maintain awareness of similar vulnerabilities in other browser components.
Mitigation strategies for CVE-2021-38494 primarily focus on immediate browser updates to Firefox version 92, which contains the necessary security patches to address the identified memory safety issues. System administrators should prioritize deployment of the Firefox 92 update across all affected systems, implementing staged rollouts to minimize operational disruption while ensuring comprehensive coverage. The vulnerability's nature as a memory safety issue means that traditional security measures such as firewalls or network monitoring may not prevent exploitation, emphasizing the importance of keeping software current with security patches. Organizations should also consider implementing additional browser hardening measures, such as disabling unnecessary browser features, configuring security policies, and monitoring for suspicious web activity. Security teams should conduct vulnerability assessments to identify any systems that may have been compromised before patch deployment, particularly focusing on systems that have not received the update. The ATT&CK framework categorizes such vulnerabilities under the T1203 technique for exploitation of remote services, highlighting the need for proactive security measures. Regular security awareness training for users can help prevent accidental exposure to malicious content that might exploit these vulnerabilities, while maintaining up-to-date security tooling and monitoring systems can provide early detection of potential exploitation attempts.