CVE-2019-25619: FTP Shell Server Buffer Overflow Flaw

CVE-2019-25619 Overview

FTP Shell Server 6.83 contains a buffer overflow vulnerability in the 'Account name to ban' field that allows local attackers to execute arbitrary code by supplying a crafted string. This vulnerability is classified under CWE-787 (Out-of-Bounds Write), which occurs when software writes data past the end or before the beginning of the intended buffer.

Attackers can inject shellcode through the account name parameter in the Manage FTP Accounts dialog to overwrite the return address and execute arbitrary commands such as calc.exe or other malicious payloads.

Critical Impact

Local attackers can achieve arbitrary code execution by exploiting the buffer overflow in the account name field, potentially leading to complete system compromise.

Affected Products

• FTP Shell Server version 6.83

Discovery Timeline

• 2026-03-22 - CVE-2019-25619 published to NVD
• 2026-03-23 - Last updated in NVD database

Technical Details for CVE-2019-25619

Vulnerability Analysis

This buffer overflow vulnerability exists in FTP Shell Server 6.83 within the 'Account name to ban' functionality found in the Manage FTP Accounts dialog. The application fails to properly validate the length of user-supplied input before copying it into a fixed-size buffer, allowing an attacker to overwrite adjacent memory including the return address on the stack.

The vulnerability is exploitable locally with no privileges required and requires no user interaction beyond the attacker having access to the FTP Shell Server administrative interface. Successful exploitation results in complete compromise of confidentiality, integrity, and availability on the vulnerable host.

Root Cause

The root cause of this vulnerability is improper bounds checking on the 'Account name to ban' input field. When processing the account name string, the application uses an unsafe memory copy operation that does not validate whether the input length exceeds the destination buffer's allocated size. This allows an attacker to write data beyond the buffer boundary, corrupting adjacent stack memory including saved return addresses.

Attack Vector

This is a local attack vector vulnerability that requires the attacker to have access to the FTP Shell Server management interface. The attack is performed by:

1. Accessing the Manage FTP Accounts dialog within FTP Shell Server
2. Navigating to the 'Account name to ban' input field
3. Supplying a specially crafted string containing padding bytes to reach the return address, followed by shellcode or a pointer to malicious code
4. The overwritten return address redirects execution flow to the attacker's payload when the vulnerable function returns

The exploitation mechanism involves overwriting the stack-based return address with a controlled value, allowing the attacker to redirect program execution to injected shellcode or existing code gadgets. For more technical details, refer to the Exploit-DB #46685 entry or the VulnCheck Advisory.

Detection Methods for CVE-2019-25619

Indicators of Compromise

• Unusual process spawning from ftpshell.exe or related FTP Shell Server processes
• Execution of unexpected child processes such as calc.exe, cmd.exe, or powershell.exe from the FTP Shell Server application
• Stack buffer overflow signatures in application crash logs or Windows Event Viewer
• Anomalous memory access patterns or access violation exceptions in FTP Shell Server logs

Detection Strategies

• Monitor for buffer overflow attack patterns targeting FTP Shell Server processes using endpoint detection and response (EDR) solutions
• Implement process behavior monitoring to detect unexpected child process creation from FTP Shell Server
• Deploy application whitelisting to prevent unauthorized code execution following exploitation
• Review Windows Event Logs for application crashes with exception code 0xC0000005 (Access Violation) related to FTP Shell Server

Monitoring Recommendations

• Enable verbose logging for FTP Shell Server administrative actions
• Monitor for suspicious account management activities, particularly those involving unusually long account names
• Implement network segmentation to limit access to FTP Shell Server administrative interfaces
• Deploy SentinelOne Singularity to detect and block buffer overflow exploitation attempts in real-time

How to Mitigate CVE-2019-25619

Immediate Actions Required

• Restrict access to the FTP Shell Server administrative interface to trusted administrators only
• Consider disabling or limiting the 'Account name to ban' functionality if not required
• Implement network segmentation to isolate systems running FTP Shell Server
• Deploy endpoint protection solutions capable of detecting and preventing buffer overflow exploitation
• Evaluate replacing FTP Shell Server with an alternative FTP server solution that receives active security updates

Patch Information

No vendor patch information is currently available for this vulnerability. The product documentation can be found at the FTP Shell official website. Users should contact the vendor directly to inquire about security updates or consider migrating to an actively maintained FTP server solution.

Workarounds

• Limit administrative access to FTP Shell Server to trusted users only and use strong authentication
• Run FTP Shell Server with minimal privileges using the principle of least privilege
• Implement input length restrictions at the network or application firewall level if possible
• Deploy Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) at the operating system level to make exploitation more difficult
• Consider running FTP Shell Server in an isolated virtual machine or container environment to limit the blast radius of potential exploitation

# Enable DEP for all processes on Windows (run as Administrator)
bcdedit /set nx AlwaysOn

# Verify DEP status
wmic OS Get DataExecutionPrevention_SupportPolicy