CVE-2010-4816 in FreeBSD
Summary
by MITRE • 06/22/2021
It was found in FreeBSD 8.0, 6.3 and 4.9, and OpenBSD 4.6 that a null pointer dereference in ftpd/popen.c may lead to remote denial of service of the ftpd service.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/24/2021
The vulnerability identified as CVE-2010-4816 represents a critical null pointer dereference flaw within the ftpd service implementation of FreeBSD and OpenBSD operating systems. This issue affects multiple versions including FreeBSD 8.0, 6.3, and 4.9, as well as OpenBSD 4.6, demonstrating the widespread nature of the problem across different system releases. The vulnerability is particularly concerning because it exists within the core ftpd service functionality, which serves as a fundamental network service for file transfer operations in these operating systems.
The technical flaw manifests in the ftpd/popen.c source file where improper input validation and error handling lead to a situation where a null pointer is dereferenced during specific ftpd operations. This occurs when the ftpd service processes certain commands or data sequences that trigger the execution path containing the faulty pointer handling logic. The null pointer dereference vulnerability falls under the CWE-476 category, which specifically addresses the dereferencing of null pointers, a common class of programming errors that can lead to service interruptions and system instability. The flaw typically arises when the ftpd service attempts to process user-supplied data without adequate validation, causing the program to attempt to access memory at address zero.
The operational impact of this vulnerability is significant as it allows remote attackers to trigger a denial of service condition against the ftpd service. An attacker can craft specific ftp commands or data sequences that will cause the service to crash or terminate unexpectedly, thereby preventing legitimate users from accessing file transfer services. This remote denial of service attack can be executed without requiring authentication, making it particularly dangerous in networked environments where ftpd services are exposed to untrusted users. The service interruption can persist until manual intervention occurs or the system is rebooted, potentially disrupting business operations and file transfer capabilities for legitimate users.
The vulnerability demonstrates a classic security weakness in network service implementations where input validation is insufficient to handle malformed or unexpected data sequences. From an attack perspective, this flaw aligns with ATT&CK technique T1499.004, which involves network denial of service attacks targeting services. The implementation of proper input validation, memory management practices, and error handling within network services is crucial to prevent such vulnerabilities. System administrators should prioritize patching affected systems immediately, as the vulnerability can be exploited remotely without authentication. Additionally, implementing network segmentation and limiting exposure of ftpd services to trusted networks can provide additional defense in depth measures to mitigate the risk of exploitation.