CVE-2018-5100 in Firefox
Summary
by MITRE
A use-after-free vulnerability can occur when arguments passed to the "IsPotentiallyScrollable" function are freed while still in use by scripts. This results in a potentially exploitable crash. This vulnerability affects Firefox < 58.
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Analysis
by VulDB Data Team • 12/30/2019
The vulnerability identified as CVE-2018-5100 represents a critical use-after-free condition within the Mozilla Firefox browser that emerged in versions prior to 58. This flaw occurs within the IsPotentiallyScrollable function where argument memory management becomes problematic, creating opportunities for malicious exploitation. The issue stems from improper handling of memory references where arguments passed to this specific function are freed from memory while still being actively referenced by JavaScript execution contexts. Such memory corruption scenarios create unpredictable behavior that can be leveraged by attackers to execute arbitrary code on affected systems. The vulnerability specifically affects Firefox versions below 58, making it a significant concern for users running outdated browser installations. The use-after-free condition creates a memory access violation that can lead to application crashes, but more critically, provides a potential pathway for remote code execution through carefully crafted web content.
The technical implementation of this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in memory management. This weakness occurs when a program continues to reference memory after it has been freed, creating a scenario where subsequent memory allocations may overwrite the freed memory space. In the context of web browsers, this becomes particularly dangerous as JavaScript engines frequently interact with native code through complex memory management systems. The IsPotentiallyScrollable function appears to be part of Firefox's layout engine responsible for determining scrollable elements, making it a core component in rendering web content. When arguments to this function are prematurely freed, the JavaScript engine may attempt to access invalid memory addresses, resulting in crashes or potentially exploitable memory corruption states.
From an operational perspective, this vulnerability presents a significant risk to users who have not updated their Firefox installations to version 58 or later. Attackers can exploit this flaw by crafting malicious web pages that trigger the vulnerable code path through specific JavaScript interactions with scrollable elements. The exploitability of this condition is enhanced by the fact that it operates within the browser's rendering pipeline, meaning users can be compromised simply by visiting malicious websites. The crash conditions that result from this vulnerability can be reliably triggered through JavaScript manipulation, making it a preferred target for exploit development. Security researchers have noted that the memory corruption patterns associated with use-after-free vulnerabilities often allow for sophisticated exploitation techniques including heap spraying and return-oriented programming attacks.
The mitigation strategy for CVE-2018-5100 primarily involves upgrading to Firefox version 58 or later, which includes patches that properly handle memory management within the IsPotentiallyScrollable function. Mozilla released this update as part of their regular security patch cycle, addressing the underlying memory management issues that allowed the use-after-free condition to occur. Organizations should implement immediate remediation measures to ensure all users are running patched versions of the browser, as the vulnerability represents a high-severity risk that can be exploited remotely. System administrators should also consider implementing additional security measures such as browser hardening configurations and content security policies to reduce the attack surface. The vulnerability's classification under ATT&CK technique T1203 demonstrates its potential for process injection and code execution, making it a critical target for security teams to address through comprehensive patch management programs. Regular security assessments should include verification of browser versions and patch status to prevent exploitation of this and similar memory corruption vulnerabilities that continue to pose risks in web browser environments.