CVE-2004-2523 in FTP Server
Summary
by MITRE
Format string vulnerability in the msg command (cat_message function in msg.c) in OpenFTPD 0.30.2 and earlier allows remote authenticated users to execute arbitrary code via format string specifiers in the message argument.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2004-2523 represents a critical format string vulnerability within the OpenFTPD 0.30.2 and earlier versions, specifically within the msg command implementation. This flaw exists in the cat_message function located in the msg.c source file, creating a pathway for remote authenticated attackers to execute arbitrary code on affected systems. The vulnerability stems from improper input validation and handling of user-supplied data within the message argument processing, allowing attackers to manipulate printf-style format specifiers that are subsequently processed without adequate sanitization.
The technical exploitation of this vulnerability occurs when an authenticated user sends a specially crafted message containing format string specifiers to the FTP server. These specifiers can reference arbitrary memory locations and can be used to read or write data at specific addresses, potentially leading to stack smashing, information disclosure, or complete code execution. The vulnerability is classified under CWE-134 as "Use of Externally-Controlled Format String" which is a well-documented weakness in software systems where external input is directly used in format string functions without proper validation or sanitization. This weakness allows attackers to manipulate the format string processing behavior to achieve unauthorized actions.
From an operational perspective, the impact of this vulnerability is severe as it requires only authenticated access to exploit, significantly reducing the attack surface compared to unauthenticated exploits. An attacker with valid FTP credentials can leverage this vulnerability to execute arbitrary commands with the privileges of the FTP daemon process, potentially leading to complete system compromise. The vulnerability affects the confidentiality, integrity, and availability of the affected system, as it can be used to read sensitive information from memory, overwrite critical data structures, or inject malicious code into the running process. This type of vulnerability is particularly dangerous in multi-tenant environments where multiple users share the same FTP service.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, specifically the privilege escalation and code execution phases. The vulnerability enables an attacker to move from a limited authenticated session to a position of complete system control, which can be categorized under technique T1068 for "Exploitation for Privilege Escalation" and T1059 for "Command and Scripting Interpreter." Organizations should implement immediate mitigations including applying the vendor-provided patch for OpenFTPD version 0.30.3 or later, which addresses the format string vulnerability through proper input validation and sanitization of user-supplied message arguments. Additionally, network segmentation and access control measures should be implemented to limit the potential impact of such vulnerabilities, and regular security assessments should be conducted to identify similar weaknesses in other network services.