CVE-2017-12170 in Pure-FTPd
Summary
by MITRE
Downstream version 1.0.46-1 of pure-ftpd as shipped in Fedora was vulnerable to packaging error due to which the original configuration was ignored after update and service started running with default configuration. This has security implications because of overriding security-related configuration. This issue doesn't affect upstream version of pure-ftpd.
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Analysis
by VulDB Data Team • 11/18/2019
The vulnerability identified as CVE-2017-12170 represents a critical packaging configuration error within the downstream version 1.0.46-1 of pure-ftpd distributed through Fedora Linux. This issue stems from a flawed update mechanism that fails to preserve existing security configurations during software upgrades, effectively resetting the service to its default state regardless of previously established security parameters. The root cause lies in the package management and update procedures specific to the Fedora distribution, rather than inherent flaws in the pure-ftpd software itself. When administrators configure security-sensitive parameters such as authentication methods, access controls, or encryption settings, these customizations are systematically overwritten during routine updates, leaving the FTP service running with potentially dangerous default configurations that may expose the system to unauthorized access or data breaches.
The technical implications of this vulnerability extend beyond simple configuration reset, as it directly violates fundamental security principles of configuration management and system hardening. According to CWE-16, this represents a weakness in the software's configuration management process, where the system fails to maintain security-relevant settings during updates. The vulnerability creates a persistent security gap that can be exploited by attackers who understand the default configuration behavior of pure-ftpd, potentially gaining unauthorized access to file systems or executing malicious operations through the FTP service. The default configuration typically includes weaker security controls such as less restrictive authentication mechanisms, broader access permissions, or reduced encryption standards that make the system more susceptible to various attack vectors including credential theft, data exfiltration, and privilege escalation.
The operational impact of CVE-2017-12170 is significant for organizations relying on Fedora-based systems with deployed pure-ftpd services, as it creates an automatic degradation of security posture during routine maintenance activities. System administrators may remain unaware of this configuration override until a security incident occurs, since the service continues to operate normally without explicit error indications. This vulnerability specifically affects the ATT&CK technique T1078.002 which involves valid accounts and credential access, as compromised FTP services can provide attackers with persistent access to systems through default or weakly configured accounts. The issue also relates to T1566.001 which covers spearphishing via social engineering, as attackers can exploit the default configurations to establish footholds that persist through system updates, undermining the security controls that administrators believe they have implemented.
Organizations should implement immediate mitigations including verification of current package versions and manual configuration backup procedures before applying updates, along with implementing monitoring systems to detect configuration changes in critical services. The recommended approach involves establishing a configuration management strategy that includes regular audits of service configurations, implementing automated tools to track configuration drift, and ensuring that update procedures include explicit steps to preserve security settings. System administrators should also consider implementing configuration management solutions such as puppet, ansible, or chef to maintain consistent security policies across systems and prevent the unintended overwrites that occur with this packaging error. Additionally, organizations should verify that they are not running the vulnerable downstream version and consider upgrading to versions that have addressed this packaging issue, while also implementing network segmentation and access controls to limit exposure of FTP services to trusted networks only.