CVE-2019-18217 Scanner

ProFTPD is a widely-used FTP server software implemented for Unix-like systems, commonly used for secure file transfer needs. It is utilized by system administrators and developers for managing file storage and retrieval through a command-line interface. As an open-source solution, it supports a range of FTP protocol extensions and provides flexibility in configuration. The software is often employed in environments that require robust, yet flexible file sharing and authentication mechanisms. Due to its modular design, ProFTPD can be adapted to fulfill specific organizational or personal security and file-sharing requirements. Its compatibility with various system setups makes it a go-to choice for developers and IT infrastructure teams.

The vulnerability identified in ProFTPD versions before 1.3.6b involves a denial of service through remote unauthenticated means. This flaw manifests when excessively long commands are handled by the server, leading to infinite loops within a child process. Such loops can eventually cause the server to crash, interrupting any ongoing file transfer processes. An attacker may exploit this to disrupt regular server operations without needing authentication, making it a significant threat in multi-user environments. Due to its high severity, as indicated by a CVSS score of 7.5, addressing this flaw is paramount to maintain uninterrupted services.

The core technical detail surrounds the handling of overly long commands by versions of ProFTPD prior to 1.3.6b. When these commands are processed, a flaw in command parsing causes the server to enter an infinite loop. The trigger of this loop resides in child processes responsible for managing client request inputs. This ultimately leads to resource exhaustion and potential unavailability of the server for handling further legitimate requests. Additionally, the lack of authentication further eases exploitation, posing a substantial risk to server accessibility.

Successful exploitation of this vulnerability can lead to service disruptions, with the server being unable to process any additional requests. The downtime of file sharing services might result in severe operational bottlenecks or interrupted end-user experiences. E-commerce platforms or enterprises relying on rapid file exchanges could face significant setbacks. Consequently, the affected systems will experience lower productivity and could lead to reputational damage if services remain offline for extended durations due to malicious activity.

REFERENCES

• http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00009.html
• https://cert-portal.siemens.com/productcert/pdf/ssa-940889.pdf
• https://github.com/proftpd/proftpd/blob/1.3.6/NEWS
• https://github.com/proftpd/proftpd/blob/1.3.6/RELEASE_NOTES
• https://github.com/proftpd/proftpd/blob/master/NEWS