CVE-2007-1870 in lighttpd
Summary
by MITRE
lighttpd before 1.4.14 allows attackers to cause a denial of service (crash) via a request to a file whose mtime is 0, which results in a NULL pointer dereference.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/18/2019
The vulnerability identified as CVE-2007-1870 affects lighttpd web server versions prior to 1.4.14, presenting a critical denial of service condition that can be exploited by remote attackers. This flaw specifically manifests when the web server processes requests for files with a modification time (mtime) set to zero, creating a scenario where the server crashes due to a NULL pointer dereference. The vulnerability represents a classic software defect that demonstrates poor error handling and input validation within the server's file processing logic.
The technical root cause of this vulnerability lies in the improper handling of file metadata within the lighttpd codebase. When the web server encounters a file with mtime set to zero, the internal processing routines fail to properly validate this condition before attempting to dereference pointers associated with the file's metadata. This NULL pointer dereference occurs because the server assumes certain file attributes will always contain valid data, but when mtime equals zero, the expected data structures become invalid or uninitialized. The vulnerability maps to CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations, making it a straightforward yet dangerous flaw that can be easily exploited.
The operational impact of this vulnerability extends beyond simple service disruption, as it allows attackers to remotely crash the lighttpd server without requiring any authentication or special privileges. This makes it particularly dangerous in production environments where server availability is critical, as an attacker can repeatedly exploit this condition to maintain persistent denial of service attacks against web applications. The vulnerability affects the server's ability to process legitimate requests and can lead to complete service unavailability, potentially impacting business operations and user access to web resources. The attack vector is simple and requires only a single HTTP request to a file with zero mtime, making it extremely accessible to malicious actors.
Mitigation strategies for CVE-2007-1870 primarily focus on immediate software updates to version 1.4.14 or later, which contains the necessary patches to properly handle files with zero mtime values. Organizations should also implement monitoring systems to detect unusual patterns in file metadata that might indicate attempted exploitation. Network-level protections such as intrusion detection systems can be configured to detect and block requests targeting files with suspicious metadata. Additionally, system administrators should conduct thorough security audits of their web server configurations to identify any other potential vulnerabilities in the software stack. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks and demonstrates how seemingly minor implementation flaws can create significant security risks. The fix implemented in lighttpd 1.4.14 involves proper validation of file metadata and robust error handling to prevent the NULL pointer dereference condition, establishing a strong precedent for defensive programming practices in web server software.