CVE-2012-6067 in FTP
Summary
by MITRE
freeFTPd.exe in freeFTPd through 1.0.11 allows remote attackers to bypass authentication via a crafted SFTP session, as demonstrated by an OpenSSH client with modified versions of ssh.c and sshconnect2.c.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-6067 affects freeFTPd versions 1.0.11 and earlier, specifically targeting the freeFTPd.exe component that handles SFTP sessions. This authentication bypass flaw represents a critical security weakness that allows remote attackers to gain unauthorized access to the FTP server without proper credentials. The vulnerability manifests through crafted SFTP sessions that exploit weaknesses in the authentication handling mechanisms of the freeFTPd implementation.
The technical exploitation of this vulnerability involves manipulating the SFTP protocol implementation within freeFTPd to circumvent normal authentication procedures. Attackers can leverage modified OpenSSH client components, specifically by altering ssh.c and sshconnect2.c source files, to establish SFTP connections that bypass the standard authentication checks. This demonstrates a fundamental flaw in how the software processes authentication requests within SFTP sessions, allowing malicious actors to authenticate without providing valid credentials or passwords. The vulnerability specifically targets the SFTP subsystem rather than the traditional FTP protocol, making it particularly concerning for environments that rely on secure file transfer capabilities.
From an operational impact perspective, this vulnerability creates a significant risk for organizations using freeFTPd as their primary file transfer solution. Remote attackers can gain full access to the file system, potentially leading to data exfiltration, system compromise, or unauthorized modification of critical files. The vulnerability affects the integrity and confidentiality of data stored on the affected servers, as well as potentially enabling lateral movement within networks where these FTP servers are deployed. Organizations may experience unauthorized access to sensitive information, disruption of services, and potential compliance violations depending on the nature of the data being transferred.
The vulnerability aligns with CWE-287, which addresses improper authentication issues in software implementations. This classification indicates that the flaw stems from inadequate validation of authentication credentials and insufficient protection against unauthorized access attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation, specifically targeting the T1110.003 sub-technique for unauthorized access to systems through authentication bypass methods. The attack vector leverages the SFTP protocol to exploit weaknesses in the authentication flow, making it particularly challenging to detect as it appears to be a legitimate SFTP connection attempt.
Mitigation strategies for this vulnerability require immediate patching of the freeFTPd software to version 1.0.12 or later, which contains the necessary fixes to address the authentication bypass flaw. Organizations should also implement network segmentation to limit access to FTP servers and monitor for unusual SFTP connection patterns that might indicate exploitation attempts. Additional protective measures include disabling SFTP functionality if not required, implementing strong network access controls, and conducting regular security assessments of file transfer services. System administrators should also consider deploying intrusion detection systems that can identify anomalous SFTP behavior patterns and establish robust monitoring procedures for authentication events. The vulnerability highlights the importance of maintaining up-to-date security software and implementing defense-in-depth strategies to protect against protocol-level exploitation attempts.