CVE-2006-6767 in oftpd
Summary
by MITRE
oftpd before 0.3.7 allows remote attackers to cause a denial of service (daemon abort) via a (1) LPRT or (2) LPASV command with an unsupported address family, which triggers an assertion failure.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2006-6767 affects oftpd versions prior to 0.3.7 and represents a denial of service weakness that can be exploited remotely by attackers. This issue specifically targets the FTP daemon implementation where improper handling of certain FTP commands leads to daemon termination. The vulnerability manifests when an attacker sends either an LPRT or LPASV command with an unsupported address family parameter, causing the daemon to encounter an assertion failure that results in abrupt termination. This type of vulnerability falls under the category of improper input validation and weak error handling within network services.
The technical flaw stems from the daemon's insufficient validation of address family parameters in the LPRT (Large Port) and LPASV (Large Active) FTP commands. These commands are used for establishing data connections in FTP transfers and typically include address family information as part of their parameter structure. When the oftpd daemon receives these commands with unsupported address families, it fails to properly validate the input and instead triggers an assertion failure that causes the process to abort. This assertion failure represents a classic example of inadequate error handling where the software does not gracefully manage unexpected input conditions. The vulnerability operates at the protocol level and specifically targets the data connection establishment mechanism, making it particularly impactful for FTP services that rely on these commands for proper operation.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by remote attackers without requiring authentication or privileged access. An attacker can simply connect to the FTP daemon and send maliciously crafted LPRT or LPASV commands with unsupported address family values to cause the daemon to crash and terminate. This results in a complete denial of service condition where legitimate users cannot access the FTP service until the daemon is manually restarted. The vulnerability is particularly concerning because it can be exploited by anyone who can reach the FTP service, making it a low-hanging fruit for attackers seeking to disrupt FTP operations. The daemon abort creates a cascading effect that can impact not only the FTP service but potentially affect other systems dependent on that service.
Mitigation strategies for CVE-2006-6767 primarily involve upgrading to oftpd version 0.3.7 or later, which contains the necessary patches to properly validate address family parameters in the affected FTP commands. Organizations should also implement network-level controls such as firewall rules that restrict access to FTP services to trusted networks only, and consider deploying intrusion detection systems that can monitor for suspicious FTP command sequences. Additionally, administrators should ensure that FTP services are properly monitored for abnormal termination patterns and that automated restart mechanisms are in place to minimize service disruption. From a compliance perspective, this vulnerability aligns with CWE-248, which addresses the issue of an exception being thrown but not caught, and relates to ATT&CK technique T1499.1, which covers network denial of service attacks. Organizations should also consider implementing network segmentation to limit the blast radius of such attacks and ensure that critical FTP services are protected by multiple layers of security controls.