CVE-2007-5962 in Fedora
Summary
by MITRE
Memory leak in a certain Red Hat patch, applied to vsftpd 2.0.5 on Red Hat Enterprise Linux (RHEL) 5 and Fedora 6 through 8, and on Foresight Linux and rPath appliances, allows remote attackers to cause a denial of service (memory consumption) via a large number of CWD commands, as demonstrated by an attack on a daemon with the deny_file configuration option.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability described in CVE-2007-5962 represents a critical memory management flaw within the vsftpd FTP server implementation on specific Linux distributions. This issue manifests as a memory leak that occurs when the vsftpd daemon processes a large number of CWD (Change Working Directory) commands, particularly when the daemon is configured with the deny_file option. The vulnerability affects multiple platforms including Red Hat Enterprise Linux 5, Fedora versions 6 through 8, as well as Foresight Linux and rPath appliances, indicating a widespread impact across various enterprise and appliance environments. The memory leak vulnerability falls under the CWE-401 category of CWE-401: Improper Release of Memory, which specifically addresses issues where allocated memory is not properly deallocated, leading to resource exhaustion.
The technical exploitation of this vulnerability occurs through a straightforward yet effective method involving repeated CWD commands sent to the vulnerable vsftpd daemon. When the daemon processes these commands while operating with the deny_file configuration, it fails to properly release memory that was allocated during the processing of each CWD command. This memory consumption continues incrementally with each command received, eventually leading to complete memory exhaustion of the system. The attack demonstrates a classic denial of service scenario where legitimate system resources are consumed by malicious actors, rendering the service unavailable to legitimate users. The vulnerability is particularly dangerous because it can be executed remotely without requiring authentication, making it an attractive target for attackers seeking to disrupt FTP services.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire system stability and availability. In enterprise environments where FTP services are critical for file transfers and system administration, this memory leak could lead to complete service outages that affect business operations. The vulnerability affects systems where vsftpd is configured with deny_file options, which are commonly used to restrict access to certain files or directories, making this attack vector particularly relevant in production environments. The memory consumption pattern suggests that the leak occurs during the processing of directory change operations, indicating that the issue is specifically within the file system interaction handling code of the FTP daemon. This flaw demonstrates poor resource management practices that can be exploited to consume system resources over time.
Mitigation strategies for CVE-2007-5962 should focus on both immediate patching and operational security measures. The most effective solution involves applying the official Red Hat patches that address the memory leak in vsftpd 2.0.5, which would resolve the underlying code issue causing improper memory deallocation. Organizations should also consider implementing rate limiting or connection throttling mechanisms to prevent abuse of the vulnerability through excessive CWD commands. Monitoring systems for unusual memory consumption patterns and implementing automated alerts when memory usage exceeds normal thresholds can help detect exploitation attempts. Additionally, administrators should review and test the deny_file configuration options to ensure they are properly implemented and do not inadvertently create additional attack surfaces. The vulnerability highlights the importance of proper memory management in server applications and aligns with ATT&CK technique T1499.004 for Network Denial of Service, specifically targeting service availability through resource exhaustion attacks. Organizations should also consider implementing network segmentation and firewall rules to limit access to FTP services and reduce the attack surface available to potential exploiters.