CVE-2018-25226 Overview
CVE-2018-25226 is a buffer overflow vulnerability affecting FTPShell Server version 6.83. The vulnerability allows local attackers to crash the application by supplying an excessively long string in the account name field. Specifically, attackers can trigger a denial of service by pasting a 417-byte payload into the 'Account name to ban' parameter within the Manage FTP Accounts interface.
Critical Impact
Local attackers can crash FTPShell Server 6.83 by exploiting the buffer overflow in the account management interface, causing denial of service and potential service disruption for FTP operations.
Affected Products
- FTPShell Server version 6.83
- ftpshell ftpshell_server (cpe:2.3:a:ftpshell:ftpshell_server:6.83:*:*:*:*:*:*:*)
Discovery Timeline
- 2026-03-30 - CVE-2018-25226 published to NVD
- 2026-03-31 - Last updated in NVD database
Technical Details for CVE-2018-25226
Vulnerability Analysis
This vulnerability is classified as CWE-787 (Out-of-bounds Write), commonly known as a buffer overflow. The flaw exists within the account management functionality of FTPShell Server 6.83. When processing input in the 'Account name to ban' parameter, the application fails to properly validate the length of user-supplied data before copying it into a fixed-size buffer.
The vulnerability requires local access to exploit, meaning an attacker must have some level of access to the system running FTPShell Server. While the impact is limited to availability (causing a crash), it can disrupt FTP services for all users relying on the affected server.
Root Cause
The root cause stems from inadequate input validation and boundary checking when handling the account name field in the Manage FTP Accounts interface. The application does not properly verify that the input string length falls within the expected buffer size before writing to memory, leading to an out-of-bounds write condition when a string exceeding approximately 417 bytes is supplied.
Attack Vector
The attack requires local access to the FTPShell Server management interface. An attacker with access to the administrative console can navigate to the Manage FTP Accounts section and enter an excessively long string (417 bytes or more) into the 'Account name to ban' field. When the application attempts to process this oversized input, it writes beyond the allocated buffer boundaries, corrupting adjacent memory and causing the application to crash.
The vulnerability mechanism involves a classic buffer overflow pattern where user input is copied to a fixed-size buffer without length validation. When the input exceeds 417 bytes, the write operation overflows the designated memory region. For technical details and proof-of-concept information, refer to the Exploit-DB #46430 entry.
Detection Methods for CVE-2018-25226
Indicators of Compromise
- Unexpected FTPShell Server process crashes or service terminations
- Windows application error logs showing FTPShell Server crash events
- Memory access violation errors in system logs related to FTPShell processes
- Multiple rapid service restart attempts indicating repeated exploitation
Detection Strategies
- Monitor for FTPShell Server process crashes using Windows Event Logs (Application Log, Event ID 1000 for application crashes)
- Implement endpoint detection rules to alert on abnormal memory access patterns in ftpshell_server.exe
- Configure SentinelOne to detect buffer overflow exploitation attempts targeting the FTPShell Server process
- Set up service availability monitoring to detect unexpected FTP service disruptions
Monitoring Recommendations
- Enable verbose logging within FTPShell Server to capture administrative actions in the Manage FTP Accounts interface
- Monitor for unusual access patterns to the FTPShell administrative console
- Track process stability metrics for critical FTP services to identify potential DoS conditions
- Implement alerting for repeated FTPShell Server crashes within short timeframes
How to Mitigate CVE-2018-25226
Immediate Actions Required
- Restrict access to the FTPShell Server administrative interface to trusted administrators only
- Implement network segmentation to limit local access to systems running FTPShell Server
- Consider migrating to an alternative FTP server solution with active security maintenance
- Monitor FTPShell Server for any signs of exploitation or unexpected crashes
Patch Information
No vendor patches are currently documented in the available advisory data. The FTPShell Homepage and FTPShell Download Server Page should be monitored for any security updates. Organizations should also reference the VulnCheck Advisory: FTPShell DoS for additional guidance.
Workarounds
- Limit administrative access to the FTPShell Server management interface to only essential personnel
- Implement operating system-level access controls to restrict who can interact with the FTPShell Server configuration
- Deploy endpoint protection solutions like SentinelOne to detect and prevent exploitation attempts
- Consider running FTPShell Server in a sandboxed or isolated environment to minimize impact of potential crashes
- Evaluate alternative FTP server solutions that receive active security updates
# Example: Restrict access to FTPShell Server management (Windows)
# Limit administrative access via Windows User Rights Assignment
# Computer Configuration > Windows Settings > Security Settings > Local Policies > User Rights Assignment
# Remove non-essential users from local administrators group
net localgroup administrators username /delete
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
