CVE-2018-5124 in Firefox
Summary
by MITRE
Unsanitized output in the browser UI leaves HTML tags in place and can result in arbitrary code execution in Firefox before version 58.0.1.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability identified as CVE-2018-5124 represents a critical cross-site scripting flaw in Mozilla Firefox browsers prior to version 58.0.1. This issue stems from inadequate input sanitization within the browser's user interface components, specifically affecting how HTML content is processed and displayed. The vulnerability allows attackers to inject malicious HTML tags into browser UI elements without proper sanitization, creating a pathway for arbitrary code execution. The flaw exists in the browser's rendering engine where unsanitized output is directly passed to the user interface, bypassing necessary security checks that should strip or escape potentially dangerous HTML elements.
The technical exploitation of this vulnerability involves crafting malicious content that gets rendered within Firefox's interface components. When the browser displays this unsanitized content, HTML tags remain intact and can execute within the context of the browser's privileged environment. This creates a severe security risk as attackers can leverage this weakness to inject JavaScript code, manipulate browser functionality, or escalate privileges. The vulnerability operates at the intersection of user interface rendering and security sanitization, making it particularly dangerous because it affects components that users interact with regularly. According to CWE classification, this corresponds to CWE-79: Cross-site Scripting, which specifically addresses the failure to sanitize output before rendering it in a web browser context.
The operational impact of CVE-2018-5124 extends beyond simple code execution capabilities to encompass potential privilege escalation and persistent threat vectors. Attackers can exploit this vulnerability to execute malicious scripts within the browser's security context, potentially leading to full system compromise. The affected versions of Firefox were particularly vulnerable because they lacked proper HTML sanitization in their UI rendering pipeline, allowing malicious payloads to persist in browser interface elements. This vulnerability affects not only web browsing sessions but also the browser's internal management interfaces, creating multiple attack surfaces for threat actors. The risk is amplified by the fact that users often interact with browser UI components regularly, providing numerous opportunities for exploitation.
Mitigation strategies for CVE-2018-5124 primarily focus on immediate patching and browser updates to version 58.0.1 or later, which contain the necessary sanitization fixes. Organizations should implement comprehensive browser security policies that enforce automatic updates and maintain strict control over browser versions in enterprise environments. Additional defensive measures include deploying web application firewalls that can detect and block malicious HTML injection attempts, implementing content security policies that restrict script execution, and conducting regular security assessments of browser configurations. The ATT&CK framework categorizes this vulnerability under T1059.007: Command and Scripting Interpreter: JavaScript, as exploitation requires JavaScript execution within the browser context. Security teams should also consider implementing browser hardening techniques that limit the execution of potentially malicious code and establish monitoring protocols to detect anomalous behavior patterns associated with XSS exploitation attempts.