CVE-2006-4565 in Firefox
Summary
by MITRE
Heap-based buffer overflow in Mozilla Firefox before 1.5.0.7, Thunderbird before 1.5.0.7, and SeaMonkey before 1.0.5 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a JavaScript regular expression with a "minimal quantifier."
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Analysis
by VulDB Data Team • 07/08/2019
This vulnerability represents a critical heap-based buffer overflow affecting major Mozilla applications including Firefox, Thunderbird, and SeaMonkey versions prior to 1.5.0.7. The flaw specifically occurs when processing JavaScript regular expressions containing minimal quantifiers, which are operators that specify the minimum number of occurrences for a pattern element. The vulnerability stems from inadequate input validation and memory management within the JavaScript engine's regular expression parser, creating conditions where attacker-controlled input can overflow allocated heap memory buffers. This type of vulnerability maps directly to CWE-121 Heap-based Buffer Overflow, which is classified under the broader category of memory safety errors in software development. The attack vector is particularly dangerous because it can be triggered through web content, making it exploitable in remote scenarios where malicious actors can craft specific JavaScript code to exploit the vulnerability.
The technical implementation of this flaw involves the JavaScript engine's handling of quantifier expressions in regular patterns, where minimal quantifiers such as {0,1} or {0,n} can cause unexpected memory allocation behavior. When these quantifiers are processed in certain contexts, the engine fails to properly validate the bounds of memory allocations, leading to memory corruption that can result in arbitrary code execution. The vulnerability is particularly concerning because it operates at the application level within the JavaScript interpreter, making it difficult to detect and prevent through traditional network-based security measures. The flaw demonstrates poor adherence to secure coding practices and highlights the importance of bounds checking in memory management operations. This vulnerability aligns with ATT&CK technique T1059.007 for JavaScript and associated with T1203 for Exploitation for Client Execution, where attackers leverage browser-based vulnerabilities to execute malicious code.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable complete system compromise. When exploited successfully, the buffer overflow can cause applications to crash or allow attackers to inject and execute arbitrary code with the privileges of the affected user. This creates a significant risk for end users who may encounter malicious web content or email attachments containing crafted regular expressions. The vulnerability affects a wide range of Mozilla-based applications, making it particularly dangerous as users may be exposed across multiple attack surfaces. The exploitability is enhanced by the fact that regular expressions are commonly used in web development, making this a prevalent attack surface that can be leveraged through various delivery mechanisms including compromised websites, phishing attacks, or malicious email content. Organizations and individuals must implement immediate mitigation strategies including software updates, browser security configurations, and network-based protections to prevent exploitation of this vulnerability.
The remediation approach requires immediate patching of affected applications to versions 1.5.0.7 or later for Firefox and Thunderbird, and 1.0.5 or later for SeaMonkey. Additionally, implementing browser security measures such as disabling JavaScript in untrusted environments or using security-focused browser extensions can provide additional layers of protection. Network administrators should consider implementing web content filtering solutions that can detect and block known malicious patterns in regular expressions. The vulnerability underscores the critical importance of regular security updates and the need for robust input validation in web-based applications. Organizations should also conduct security assessments to identify potential exposure points and implement monitoring solutions to detect exploitation attempts. This vulnerability serves as a reminder of the ongoing need for secure coding practices and the importance of thorough security testing in complex software applications that handle user-supplied input.