CVE-2005-4713 in Pam Mysql
Summary
by MITRE
Unspecified vulnerability in the SQL logging facility in PAM-MySQL 0.6.x before 0.6.2 and 0.7.x before 0.7pre3 allows remote attackers to cause a denial of service (segmentation fault) via unspecified vectors, probably involving the pam_mysql_sql_log function when being used in vsftpd, which does not include the IP address argument to an sprintf call.
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Analysis
by VulDB Data Team • 06/21/2019
The vulnerability identified as CVE-2005-4713 represents a critical security flaw within the PAM-MySQL authentication module, specifically affecting versions 0.6.x prior to 0.6.2 and 0.7.x prior to 0.7pre3. This issue manifests as a denial of service condition that can be triggered remotely, causing segmentation faults that crash the targeted service. The vulnerability is particularly concerning because it operates within the SQL logging facility of the PAM-MySQL module, which serves as a critical component in authentication infrastructure for many systems. The flaw specifically impacts the pam_mysql_sql_log function when utilized in conjunction with vsftpd, a widely deployed FTP daemon that relies on PAM for authentication management.
The technical root cause of this vulnerability stems from improper handling of string formatting within the pam_mysql_sql_log function. When the function processes authentication logs, it fails to properly validate or sanitize input parameters before passing them to the sprintf function. This oversight creates a classic buffer overflow scenario where the function attempts to write data to memory locations that may not be properly allocated or accessible. The absence of IP address argument handling in the sprintf call demonstrates a fundamental flaw in parameter validation that allows attackers to craft malicious input that triggers the segmentation fault. This vulnerability aligns with CWE-121, which describes the weakness of stack-based buffer overflow conditions, and represents a specific instance of improper input validation in authentication modules.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to systematically crash authentication services across multiple systems. When vsftpd utilizes PAM-MySQL for authentication, any successful exploitation of this flaw results in immediate service termination, effectively preventing legitimate users from accessing FTP services. This denial of service condition can be particularly damaging in environments where FTP services are critical for business operations, potentially leading to significant downtime and operational disruption. The vulnerability's remote exploitability means that attackers do not need local access or credentials to cause system instability, making it a particularly attractive target for malicious actors seeking to disrupt services. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, which involves network denial of service attacks that can be executed remotely without requiring privileged access.
Mitigation strategies for CVE-2005-4713 require immediate patching of affected PAM-MySQL installations to versions 0.6.2 or 0.7pre3 and later, which contain the necessary fixes for the sprintf function handling. System administrators should prioritize updating their authentication infrastructure components and verify that all vsftpd installations properly integrate with patched PAM-MySQL modules. Additional defensive measures include implementing network segmentation to limit exposure of FTP services to untrusted networks, deploying intrusion detection systems to monitor for exploitation attempts, and establishing robust logging mechanisms to detect abnormal authentication patterns that might indicate exploitation activity. The vulnerability serves as a reminder of the critical importance of input validation in authentication modules and highlights the potential for seemingly minor coding flaws to create significant security risks in widely deployed software components. Organizations should also conduct thorough vulnerability assessments of their authentication infrastructure to identify similar issues in other PAM modules or authentication services that may be susceptible to similar buffer overflow conditions.