CVE-2008-5715 in Firefox
Summary
by MITRE
Mozilla Firefox 3.0.5 on Windows Vista allows remote attackers to cause a denial of service (application crash) via JavaScript code with a long string value for the hash property (aka location.hash). NOTE: it was later reported that earlier versions are also affected, and that the impact is CPU consumption and application hang in unspecified circumstances perhaps involving other platforms.
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Analysis
by VulDB Data Team • 11/20/2024
The vulnerability identified as CVE-2008-5715 represents a denial of service flaw in Mozilla Firefox version 3.0.5 running on Windows Vista systems. This weakness specifically manifests when JavaScript code attempts to manipulate the hash property of the location object with excessively long string values. The flaw operates at the browser's JavaScript engine level where the handling of the location.hash property fails to properly manage memory allocation and processing for exceptionally long input strings. The vulnerability demonstrates characteristics consistent with CWE-129, which addresses improper validation of length or buffer size, and also aligns with CWE-400, covering unspecified resource management issues that can lead to system instability.
The technical implementation of this vulnerability exploits the browser's internal handling of URL fragments and hash values. When JavaScript code sets location.hash to a string containing thousands or millions of characters, the Firefox browser's JavaScript engine struggles to process and store this excessive data without proper bounds checking or memory management. The system's memory allocation routines become overwhelmed, leading to either application crashes or severe performance degradation that manifests as CPU saturation and complete application hangs. This behavior extends beyond the Windows Vista platform, with reports indicating similar issues occurring across different operating systems and earlier Firefox versions, suggesting a fundamental flaw in the browser's hash property handling mechanism rather than a platform-specific issue.
The operational impact of this vulnerability presents significant risks to system availability and user experience. Attackers can exploit this weakness through malicious web pages that automatically set extremely long hash values, causing Firefox to consume excessive CPU resources and potentially freeze or crash entirely. The vulnerability can be particularly dangerous in environments where users frequently access untrusted websites or when the browser is used as part of automated testing or monitoring systems. The resource consumption patterns align with attack techniques described in the mitre ATT&CK framework under the T1499 category for resource exhaustion attacks, where adversaries target system resources to disrupt normal operations. This type of vulnerability can be leveraged in distributed denial of service scenarios where multiple compromised systems simultaneously trigger the flaw, amplifying the impact on network availability.
Mitigation strategies for CVE-2008-5715 primarily focus on software updates and browser configuration adjustments. The most effective solution involves upgrading to Firefox versions that contain patches addressing the hash property handling vulnerability, which typically include improved input validation and memory management routines. System administrators should implement regular patch management protocols to ensure all browser installations remain current with security updates. Browser security settings can be adjusted to limit JavaScript execution capabilities or implement stricter input validation for URL components. Network-level protections such as web application firewalls can be configured to detect and block suspicious hash value patterns, though this approach requires careful tuning to avoid false positives. Additionally, user education regarding the risks of visiting untrusted websites and the importance of keeping browser software updated remains crucial in preventing exploitation of this vulnerability. The remediation process should also include monitoring for unusual CPU usage patterns that might indicate exploitation attempts, particularly in enterprise environments where centralized logging and alerting systems can detect anomalous behavior.