CVE-2018-5176 in Firefox
Summary
by MITRE
The JSON Viewer displays clickable hyperlinks for strings that are parseable as URLs, including "javascript:" links. If a JSON file contains malicious JavaScript script embedded as "javascript:" links, users may be tricked into clicking and running this code in the context of the JSON Viewer. This can allow for the theft of cookies and authorization tokens which are accessible to that context. This vulnerability affects Firefox < 60.
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Analysis
by VulDB Data Team • 07/20/2024
The vulnerability described in CVE-2018-5176 represents a critical security flaw in the Firefox browser's JSON Viewer extension that demonstrates the dangers of improper input validation and context-aware content rendering. This issue specifically impacts Firefox versions prior to 60, where the JSON Viewer component automatically detects and displays clickable hyperlinks from string values within JSON documents. The flaw arises from the extension's failure to properly sanitize URL strings, particularly those beginning with the javascript: protocol, which can execute arbitrary code when clicked by users. The vulnerability operates under the principle of social engineering combined with client-side code execution, creating a dangerous intersection where user interaction triggers malicious code execution in the browser context.
The technical implementation of this vulnerability stems from the JSON Viewer's automatic hyperlink detection mechanism that processes all string values within JSON structures without adequate protocol validation. When a JSON document contains a string value such as "javascript:alert(1)" or more sophisticated malicious payloads, the viewer treats these as clickable links and displays them accordingly. This behavior directly violates security principles outlined in CWE-79 - Improper Neutralization of Input During Web Page Generation, which addresses the injection of untrusted data into web applications. The vulnerability specifically enables cross-site scripting attacks by allowing malicious JavaScript code to execute within the same security context as legitimate JSON viewing functionality, thereby bypassing normal browser security restrictions that typically prevent such code execution.
The operational impact of CVE-2018-5176 extends beyond simple code execution to encompass serious data theft capabilities that align with ATT&CK technique T1071.004 - Application Layer Protocol: DNS. Attackers can craft JSON documents containing malicious javascript: links that steal cookies, authorization tokens, and other sensitive session data accessible to the browser context. When users interact with these crafted JSON files, the malicious code executes in the context of the JSON Viewer, potentially compromising user sessions and accessing protected resources. This vulnerability particularly affects web developers and security professionals who frequently work with JSON data, as they may unknowingly process malicious JSON files that contain embedded attack payloads. The attack vector relies heavily on user interaction and trust in the JSON Viewer extension, making it particularly dangerous in environments where users regularly handle external JSON data from untrusted sources.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term architectural improvements. The primary fix involves updating to Firefox version 60 or later, where the JSON Viewer has been patched to properly sanitize URL strings and reject javascript: protocol links. Organizations should implement comprehensive input validation policies that prevent the processing of potentially dangerous protocols in web applications and browser extensions. Security teams should conduct regular audits of browser extensions and plugins to ensure they properly handle untrusted input data. The vulnerability highlights the importance of following secure coding practices as outlined in OWASP Top Ten and NIST guidelines for preventing injection attacks. Additionally, implementing content security policies and sandboxing mechanisms can further reduce the impact of similar vulnerabilities by limiting the execution context and access privileges available to potentially malicious code.