CVE-2019-12815 in ProFTPD
Summary
by MITRE
An arbitrary file copy vulnerability in mod_copy in ProFTPD up to 1.3.5b allows for remote code execution and information disclosure without authentication, a related issue to CVE-2015-3306.
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Analysis
by VulDB Data Team • 11/04/2025
The vulnerability identified as CVE-2019-12815 represents a critical arbitrary file copy flaw within the mod_copy module of ProFTPD versions up to 1.3.5b. This issue arises from insufficient input validation and access control mechanisms within the module's implementation, creating a pathway for remote attackers to manipulate file system operations. The flaw specifically affects the copy functionality that allows users to copy files within the FTP server's filesystem, enabling malicious actors to copy files to arbitrary locations on the server. The vulnerability is particularly concerning because it operates without requiring authentication, making it accessible to any remote attacker with network access to the FTP service. This characteristic aligns with the common security principle that unauthenticated vulnerabilities pose the greatest risk to system integrity and confidentiality. The vulnerability demonstrates a clear violation of the principle of least privilege, as the module does not properly enforce access controls that should restrict file operations to authorized users only. The security implications extend beyond simple file manipulation to encompass potential remote code execution capabilities when combined with other vulnerabilities or misconfigurations. The flaw is classified under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" and also relates to CWE-73 as "External Control of File Name or Path," highlighting the fundamental weakness in how file paths are processed and validated within the module. This vulnerability represents a regression or continuation of similar issues found in CVE-2015-3306, indicating that security flaws in file handling modules can persist across multiple versions if proper input validation mechanisms are not consistently implemented. The operational impact of this vulnerability is severe, as it allows attackers to copy sensitive files from the server to arbitrary locations, potentially enabling information disclosure attacks. In many scenarios, attackers could leverage this capability to copy configuration files, authentication data, or other sensitive system information. The vulnerability's potential for remote code execution emerges when attackers can copy malicious files to locations where they will be executed, such as web root directories or system execution paths. The attack surface is particularly wide because FTP servers are often exposed to the internet and may host sensitive data. The mod_copy module's design appears to lack proper sanitization of file paths and insufficient validation of user inputs, allowing attackers to manipulate the copy operations through specially crafted commands. This vulnerability is categorized under the ATT&CK technique T1078 for Valid Accounts and T1059 for Command and Scripting Interpreter, as it enables attackers to establish persistent access and execute commands through the copied files. The vulnerability demonstrates a classic example of how insecure file operations can lead to privilege escalation and system compromise. Organizations running affected ProFTPD versions face significant risk of unauthorized access and potential data breaches. The lack of authentication requirements makes this vulnerability particularly dangerous in environments where FTP services are exposed to untrusted networks. The vulnerability's persistence across multiple versions suggests that security patches may not have been consistently applied or that the underlying design flaws were not properly addressed in subsequent releases. This issue highlights the critical importance of input validation and proper access control in network services. The vulnerability can be exploited through standard FTP client connections, making it accessible to attackers with minimal technical expertise. The potential for information disclosure is significant, as attackers can copy system files, configuration data, and user information to locations they control. The security implications extend to potential privilege escalation scenarios where attackers can copy malicious executables to system directories and execute them with elevated privileges. The vulnerability also raises concerns about the overall security posture of systems that rely on older FTP server implementations. The flaw's characteristics align with the broader category of file system manipulation vulnerabilities that are frequently targeted in enterprise security assessments. The vulnerability's impact is amplified by the fact that many organizations continue to use legacy FTP servers that may not receive regular security updates. The issue represents a fundamental flaw in how the mod_copy module processes user-provided file paths, lacking proper boundary checks and validation routines that should prevent malicious path manipulation. This vulnerability underscores the importance of regularly updating network services and implementing proper security controls such as network segmentation to limit exposure to such threats. The lack of authentication requirements means that this vulnerability can be exploited by any remote attacker, regardless of their credentials or authorization level. The vulnerability's classification under multiple CWE categories indicates that it represents a complex security issue involving multiple attack vectors and potential exploitation techniques.
The technical implementation of the vulnerability stems from the mod_copy module's failure to properly validate and sanitize file paths before executing copy operations. Attackers can exploit this by crafting specific commands that manipulate the destination path to copy files to unintended locations. The vulnerability's exploitation requires no authentication, which significantly reduces the attack complexity and increases the likelihood of successful compromise. This characteristic makes it particularly dangerous in environments where FTP services are exposed to public networks without proper firewall restrictions or network segmentation controls. The vulnerability's potential for remote code execution becomes apparent when attackers can copy malicious files to locations where they will be executed, such as web application directories or system execution paths. The flaw's relationship to CVE-2015-3306 indicates that similar vulnerabilities in FTP server modules have persisted over time, suggesting a pattern of inadequate security implementation in these components. The vulnerability's impact on system security is compounded by the fact that many organizations may not be aware of the specific module that is vulnerable or the exact conditions required for exploitation. Security monitoring systems may not detect this vulnerability without specific signature-based detection capabilities or behavioral analysis that identifies anomalous file copy operations. The vulnerability's persistence across multiple ProFTPD versions demonstrates the importance of thorough security reviews and code audits for network service components. Organizations should implement immediate mitigations including patching to the latest ProFTPD versions, disabling the mod_copy module if not required, or implementing network-level restrictions to limit access to the FTP service. The vulnerability's characteristics make it particularly suitable for automated exploitation by threat actors and security scanners, increasing the probability of discovery and exploitation in the wild. The flaw's design issues suggest that proper security testing and code review processes were not adequately implemented during the development lifecycle of the affected module. The vulnerability's potential for information disclosure through arbitrary file copying operations creates a significant risk for organizations handling sensitive data through FTP services. The security implications extend beyond immediate exploitation to include long-term persistence mechanisms that attackers can establish through the copied files. The vulnerability's classification under multiple ATT&CK techniques indicates that it supports various attack phases including initial access, execution, privilege escalation, and persistence. The flaw's impact on enterprise security infrastructure highlights the critical need for comprehensive vulnerability management programs that include regular security assessments of network services. Organizations should implement network segmentation and access controls to limit exposure of FTP services to untrusted networks, while also ensuring that all network services are regularly updated with security patches. The vulnerability serves as a reminder of the importance of maintaining current security practices and avoiding the use of legacy software components that may contain known vulnerabilities.