CVE-2024-1017: Gabriels FTP Server DoS Vulnerability

CVE-2024-1017 Overview

CVE-2024-1017 is a denial-of-service vulnerability in Gabriels FTP Server 1.2. The flaw is triggered by manipulation of the USERNAME argument during the FTP authentication sequence. Remote attackers can exploit the issue without authentication or user interaction, causing the FTP service to become unavailable. The vulnerability is tracked in VulDB as VDB-252287 and maps to [CWE-404] (Improper Resource Shutdown or Release). A proof-of-concept has been publicly disclosed, increasing the practical risk for exposed instances.

Critical Impact

Unauthenticated remote attackers can crash Gabriels FTP Server 1.2 by sending a crafted USERNAME value, terminating availability of the file transfer service.

Affected Products

• Gabriels FTP Server 1.2
• Deployments exposing the FTP control channel (TCP/21) to untrusted networks
• Systems where Gabriels FTP Server is used for file transfer operations

Discovery Timeline

• 2024-01-29 - CVE-2024-1017 published to the National Vulnerability Database (NVD)
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-1017

Vulnerability Analysis

The vulnerability resides in how Gabriels FTP Server 1.2 processes the USERNAME argument during the login handshake. When a malformed or oversized value is supplied, the server fails to release or properly handle the associated resource, leading to a service crash. The condition is classified as [CWE-404] Improper Resource Shutdown or Release. Exploitation requires only network reachability to the FTP control port, with no credentials or user interaction. The result is full loss of availability, while confidentiality and integrity remain unaffected.

The EPSS probability for this CVE is 0.066%, reflecting limited observed exploitation activity despite the public disclosure.

Root Cause

The root cause is improper handling of input passed to the USER command during FTP authentication. The server does not validate or constrain the USERNAME argument before consuming it, and fails to cleanly release resources when an unexpected value is supplied. This deficient error and resource management path causes the FTP service process to terminate.

Attack Vector

An attacker connects to the FTP control channel and issues a USER command containing a crafted argument. The server attempts to process the malformed input, encounters the unhandled condition, and crashes. The attack is network-based, requires no privileges, and no user interaction. A public proof-of-concept is referenced through the Packet Storm DoS Report and the VulDB entry #252287.

No verified exploit code is reproduced here. Refer to the published advisories for technical specifics.

Detection Methods for CVE-2024-1017

Indicators of Compromise

• Abrupt termination or repeated restarts of the Gabriels FTP Server process without administrative action
• Inbound TCP/21 connections immediately followed by service unavailability or connection resets
• FTP USER commands containing abnormally long or malformed USERNAME values in protocol logs
• Gaps in FTP server logs corresponding to crash events

Detection Strategies

• Monitor FTP protocol traffic for USER commands with oversized or non-printable argument values
• Track process lifecycle events for the Gabriels FTP Server binary and alert on unexpected exits
• Correlate inbound TCP/21 connections from untrusted sources with service availability metrics
• Apply network IDS/IPS signatures targeting malformed FTP authentication sequences against Gabriels FTP Server 1.2

Monitoring Recommendations

• Enable verbose FTP server logging that captures the full USER command argument
• Forward FTP and host telemetry to a centralized log platform for correlation and retention
• Alert on repeated FTP service restarts within short time windows
• Baseline normal FTP client behavior to surface anomalous authentication attempts

How to Mitigate CVE-2024-1017

Immediate Actions Required

• Restrict TCP/21 access to Gabriels FTP Server 1.2 using firewall rules, allowing only trusted source addresses
• Place affected servers behind a VPN or jump host until a patched version is deployed
• Evaluate migration to an actively maintained FTP or SFTP server given the limited vendor support for this product
• Inventory all instances of Gabriels FTP Server across the environment to identify exposure

Patch Information

The NVD entry indicates that a patch is recommended to remediate this issue. No vendor advisory URL is listed in the available CVE data. Operators should consult the VulDB entry #252287 and the VulDB CTI record for current remediation guidance, and verify the running version against any vendor-provided fixed release.

Workarounds

• Block external access to the FTP control port and require VPN connectivity for legitimate users
• Deploy a protocol-aware proxy or application firewall that validates FTP USER command arguments
• Disable the Gabriels FTP Server service if it is not in active use
• Replace Gabriels FTP Server 1.2 with a supported alternative that receives security updates

# Example: restrict FTP access to a trusted management subnet on Linux
iptables -A INPUT -p tcp --dport 21 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j DROP

# Verify the rules
iptables -L INPUT -n --line-numbers | grep ":21"