CVE-2015-0821 in Firefox
Summary
by MITRE
Mozilla Firefox before 36.0 allows user-assisted remote attackers to read arbitrary files or execute arbitrary JavaScript code with chrome privileges via a crafted web site that is accessed with unspecified mouse and keyboard actions.
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Analysis
by VulDB Data Team • 03/10/2022
The vulnerability identified as CVE-2015-0821 represents a critical security flaw in Mozilla Firefox versions prior to 36.0 that enables remote attackers to exploit user-assisted attacks through crafted web content. This vulnerability operates under the principle of privilege escalation by allowing malicious websites to execute code with chrome privileges, which are typically restricted to the browser's core components and extensions. The flaw specifically manifests when users interact with malicious web content through unspecified mouse and keyboard actions, creating a pathway for attackers to bypass standard security boundaries that normally protect against arbitrary file access and code execution.
The technical implementation of this vulnerability involves a flaw in Firefox's security model that fails to properly validate user interactions with crafted web content. Attackers can construct malicious websites that, when accessed through specific user actions, trigger code execution within the browser's privileged context. This represents a classic case of insufficient input validation and improper privilege management, where the browser fails to maintain proper isolation between user-accessible web content and its internal chrome components. The vulnerability can be categorized under CWE-264 as a permissions, privileges, and access controls issue, specifically involving improper handling of privileges and access control mechanisms.
The operational impact of CVE-2015-0821 is severe as it allows attackers to perform arbitrary file reads from the victim's system, potentially accessing sensitive data, configuration files, or personal information. Additionally, the ability to execute JavaScript code with chrome privileges means that attackers can manipulate browser internals, install malicious extensions, modify browser behavior, or even compromise the entire system if the browser is running with elevated privileges. This vulnerability directly relates to ATT&CK technique T1059.007 for JavaScript execution and T1070.004 for file and directory permissions modification, making it particularly dangerous in environments where users might encounter malicious content through phishing campaigns or compromised websites.
The exploitability of this vulnerability requires user interaction through mouse and keyboard actions, making it a user-assisted attack rather than a fully automated remote code execution vector. However, this requirement does not diminish its threat level significantly, as social engineering techniques can easily convince users to perform the necessary actions. The vulnerability demonstrates a failure in Firefox's sandboxing mechanisms and privilege separation, where the boundary between regular web content and privileged chrome operations becomes porous. Security researchers have noted that this flaw highlights the complexity of maintaining secure boundaries in modern browsers that must balance functionality with security, particularly when dealing with extension APIs and privileged operations. Organizations should implement immediate mitigation strategies including mandatory browser updates to Firefox 36.0 or later, user education about suspicious web content, and network-based filtering to prevent access to known malicious domains. The vulnerability serves as a reminder of the critical importance of keeping browser software updated and maintaining robust security practices to prevent exploitation of privilege escalation vulnerabilities.