CVE-2002-1244 in FTP Server
Summary
by MITRE
Format string vulnerability in Pablo FTP Server 1.5, 1.3, and possibly other versions, allows remote attackers to cause a denial of service and possibly execute arbitrary code via format strings in the USER command.
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Analysis
by VulDB Data Team • 09/07/2025
The vulnerability identified as CVE-2002-1244 represents a critical format string flaw within the Pablo FTP Server software versions 1.5 and 1.3, with potential prevalence in additional releases. This security weakness stems from improper input validation within the USER command processing mechanism, creating a pathway for remote attackers to exploit the system through crafted malicious input sequences. The flaw resides in the server's inability to properly sanitize user-supplied data before using it in printf-style functions, which directly violates fundamental security principles for input handling and memory management.
Format string vulnerabilities occur when application code uses user-controllable input as format specifiers in functions like printf, sprintf, or fprintf without adequate validation or sanitization. In the context of CVE-2002-1244, the Pablo FTP Server fails to properly escape or validate the username parameter provided during the USER command execution, allowing attackers to inject format specifiers that can manipulate the program's memory layout. This particular vulnerability maps directly to CWE-134, which specifically addresses the use of format strings with user-supplied data, and aligns with ATT&CK technique T1211 where adversaries leverage format string vulnerabilities to execute arbitrary code or cause system instability. The improper handling of format strings creates a fundamental breach in the server's memory management and can result in stack corruption, memory disclosure, or complete program termination.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution, making it particularly dangerous for systems that rely on FTP services for file transfers and data management. When exploited, the format string vulnerability can cause the FTP server process to crash and restart repeatedly, leading to persistent denial of service conditions that disrupt legitimate user access. More critically, skilled attackers can leverage the vulnerability to overwrite memory addresses, inject malicious code into the server process, or extract sensitive information from the server's memory space. This capability places the vulnerability in the category of high-severity issues that can result in complete system compromise, particularly when the FTP server runs with elevated privileges or has access to sensitive data repositories.
Mitigation strategies for CVE-2002-1244 must address both immediate remediation and long-term security hardening measures. The primary solution involves applying vendor patches or upgrading to versions of the Pablo FTP Server that properly validate and sanitize user input before processing format strings. Organizations should implement input validation controls that reject or escape special characters commonly used in format string attacks, including percent signs and format specifiers. Network segmentation and access controls can limit exposure by restricting direct access to FTP services from untrusted networks, while monitoring systems should be deployed to detect anomalous USER command patterns that might indicate exploitation attempts. Security configurations should also enforce strict logging of FTP authentication attempts and implement intrusion detection systems capable of identifying format string attack signatures. Additionally, system administrators should consider implementing application-level firewalls or web application firewalls that can filter out malicious input patterns before they reach the vulnerable FTP server component, thereby reducing the attack surface and providing defense-in-depth protection against this specific vulnerability class.