CVE-2007-0801 in Firefox
Summary
by MITRE
The nsExternalAppHandler::SetUpTempFile function in Mozilla Firefox 1.5.0.9 creates temporary files with predictable filenames based on creation time, which allows remote attackers to execute arbitrary web script or HTML via a crafted XMLHttpRequest.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability described in CVE-2007-0801 represents a significant security flaw in Mozilla Firefox version 1.5.0.9 that stems from improper handling of temporary file creation within the nsExternalAppHandler::SetUpTempFile function. This issue creates a predictable filename generation mechanism that exposes the browser to remote code execution attacks through crafted XMLHttpRequests. The vulnerability operates at the intersection of file system security and web application sandboxing, where the predictable naming scheme allows attackers to anticipate and manipulate temporary file locations.
The technical implementation of this flaw involves the use of time-based entropy in filename generation, which follows a predictable pattern based on system timestamps. When Firefox processes external applications or handles file operations through XMLHttpRequests, it creates temporary files in a manner that can be anticipated by remote attackers. This predictable naming convention violates fundamental security principles for temporary file creation, as it allows attackers to establish race conditions or file overwrite scenarios. The vulnerability specifically affects the nsExternalAppHandler component which manages external application interactions, making it particularly dangerous when processing untrusted web content.
The operational impact of this vulnerability extends beyond simple script execution to encompass broader security implications for web browsing environments. Attackers can leverage this flaw to execute arbitrary web scripts or HTML content on vulnerable systems, potentially leading to complete browser compromise or information disclosure. The attack vector through XMLHttpRequests is particularly concerning as it can be initiated through standard web browsing activities without requiring user interaction beyond visiting a malicious website. This vulnerability aligns with CWE-377 which addresses insecure temporary file creation practices and demonstrates the dangers of predictable entropy in security-sensitive contexts.
The exploitation of this vulnerability requires attackers to craft specific XMLHttpRequest payloads that can manipulate the temporary file creation process. The attack typically involves timing attacks where malicious content is served to the victim's browser, triggering the vulnerable code path that creates predictable temporary files. Once the temporary files are created with predictable names, attackers can potentially overwrite them with malicious content or manipulate the file system to execute arbitrary code. This attack pattern follows common exploit techniques described in the MITRE ATT&CK framework under the 'Execution' and 'Persistence' domains, where attackers leverage browser vulnerabilities to establish persistent access.
Mitigation strategies for this vulnerability should focus on implementing proper temporary file generation mechanisms that use cryptographically secure random number generation rather than time-based entropy. Browser vendors should ensure that temporary file creation employs unique identifiers that cannot be predicted by external parties. The fix typically involves modifying the nsExternalAppHandler::SetUpTempFile function to use secure randomization techniques and implementing proper file permission controls. Organizations should also consider network-level protections such as web application firewalls and browser hardening measures that can detect and block suspicious XMLHttpRequest patterns. This vulnerability highlights the importance of following security best practices outlined in standards such as NIST SP 800-53 and ISO/IEC 27001 for secure coding practices in web browsers and application frameworks.