CVE-2009-0349 in FTPShell Server
Summary
by MITRE
Stack-based buffer overflow in FTPShell Server 4.3 allows user-assisted remote attackers to cause a denial of service (persistent daemon crash) and possibly execute arbitrary code via a long string in a licensing key (aka .key) file.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability identified as CVE-2009-0349 represents a critical stack-based buffer overflow flaw within FTPShell Server version 4.3 that exposes the software to remote exploitation by malicious actors. This vulnerability specifically targets the handling of licensing key files, which are essential components for software authorization and functionality. The flaw occurs when the application processes a specially crafted .key file containing an excessively long string that exceeds the allocated stack buffer space, leading to memory corruption and potential system compromise.
The technical implementation of this vulnerability stems from inadequate input validation and bounds checking within the software's license file processing routine. When the FTPShell Server application attempts to read and parse a malformed .key file, it fails to properly verify the length of the input string before copying it into a fixed-size stack buffer. This classic buffer overflow condition creates an opportunity for attackers to overwrite adjacent memory locations, potentially corrupting the program's execution flow and control structures. The vulnerability operates under the Common Weakness Enumeration framework as CWE-121, which categorizes stack-based buffer overflow conditions that occur when insufficient bounds checking allows data to overwrite adjacent stack memory regions.
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 FTPShell Server for file transfer operations. When exploited, the buffer overflow can cause the persistent daemon process to crash repeatedly, leading to service disruption and potential denial of service conditions that affect legitimate users. The remote nature of the attack means that adversaries can exploit this vulnerability without requiring local system access, making it a significant threat vector for networked environments. This vulnerability directly aligns with ATT&CK technique T1203, which covers exploitation for persistence through the manipulation of software components, and T1499, which covers endpoint denial of service attacks.
The security implications of CVE-2009-0349 are compounded by the fact that the vulnerability can be triggered through user-assisted remote attacks, meaning that an attacker only needs to convince a legitimate user to process a maliciously crafted .key file. This attack vector significantly broadens the potential exploitation surface and makes the vulnerability more accessible to threat actors with minimal technical expertise. The persistent daemon crash aspect indicates that even if the initial exploitation attempt fails, the application may continue to crash repeatedly, creating ongoing service disruption that can be difficult to diagnose and resolve. Organizations using FTPShell Server 4.3 should immediately implement mitigation strategies including software updates, network segmentation, and input validation controls to prevent exploitation of this vulnerability. The vulnerability demonstrates the critical importance of proper input validation and memory management practices in server applications, particularly those handling user-provided data files that are essential for software licensing and authorization processes.