CVE-2001-0489 in gftp
Summary
by MITRE
Format string vulnerability in gftp prior to 2.0.8 allows remote malicious FTP servers to execute arbitrary commands.
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Analysis
by VulDB Data Team • 07/19/2019
The vulnerability identified as CVE-2001-0489 represents a critical format string flaw in the gftp client software version 2.0.7 and earlier. This vulnerability stems from improper input validation within the gftp application's handling of data received from FTP servers during file transfer operations. The flaw specifically manifests when the client processes certain responses from malicious FTP servers that contain format specifiers such as %s, %d, or %x within their data fields. These specifiers, when improperly handled by the application's printf-like functions, can cause the program to read and interpret memory locations as string data, potentially leading to arbitrary code execution.
The technical exploitation of this vulnerability occurs through a malicious FTP server that crafts specially formatted responses containing format specifiers in file names, directory listings, or other server-provided data. When the vulnerable gftp client processes these responses, the format string vulnerability allows attackers to manipulate the program's execution flow by controlling what data is read from memory locations. This type of vulnerability falls under the CWE-134 category of "Use of Externally-Controlled Format String" and represents a classic example of how improper input sanitization can lead to remote code execution. The attack vector is particularly dangerous because it requires no user interaction beyond initiating a normal FTP connection, making it a passive threat that can be exploited by any malicious FTP server.
The operational impact of this vulnerability extends beyond simple command execution, as it can enable attackers to gain complete control over systems running vulnerable versions of gftp. This includes potential privilege escalation, data theft, or use of compromised systems as launching points for further attacks within a network. The vulnerability affects a wide range of systems that rely on gftp for file transfer operations, particularly those in enterprise environments where automated FTP connections are common. From an attacker perspective, this vulnerability aligns with the MITRE ATT&CK framework under the technique of "Command and Scripting Interpreter" and "Exploitation for Client Execution" where adversaries leverage client-side vulnerabilities to execute malicious code. The threat landscape for this vulnerability is significant as it represents a privilege escalation vector that can be exploited by any attacker who can control an FTP server, making it particularly concerning for organizations that interact with untrusted FTP servers or have limited network segmentation.
The recommended mitigations for this vulnerability include immediate upgrading to gftp version 2.0.8 or later, which contains the necessary patches to properly handle format string inputs. Organizations should also implement network segmentation to limit exposure to untrusted FTP servers, deploy network monitoring solutions to detect anomalous FTP traffic patterns, and consider implementing additional input validation measures. Security teams should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions of gftp and ensure proper patch management procedures are in place. The vulnerability serves as a reminder of the importance of proper input validation and the potential consequences of format string vulnerabilities in network applications, particularly those handling data from untrusted sources. Organizations should also consider implementing alternative file transfer protocols such as SFTP or FTPS that provide better security guarantees and are less susceptible to such vulnerabilities.