CVE-2023-2989: Globalscape EFT Server Auth Bypass Flaw

CVE-2023-2989 Overview

CVE-2023-2989 is an out-of-bounds memory read vulnerability affecting Fortra Globalscape EFT (Enterprise File Transfer) versions before 8.1.0.16. The vulnerability exists in the administration server component and can allow an attacker to crash the service or bypass authentication if successfully exploited. This security flaw enables remote attackers to access the administration server without proper credentials, potentially gaining unauthorized control over enterprise file transfer operations.

Critical Impact

Remote attackers can exploit this out-of-bounds memory read to bypass authentication controls on the Globalscape EFT administration server, potentially gaining unauthorized administrative access to enterprise file transfer infrastructure without valid credentials.

Affected Products

• Globalscape EFT Server versions prior to 8.1.0.16
• Fortra Globalscape EFT Administration Server component

Discovery Timeline

• June 22, 2023 - CVE-2023-2989 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-2989

Vulnerability Analysis

This vulnerability stems from an out-of-bounds memory read condition (CWE-125) in the Globalscape EFT administration server. When processing certain requests, the server fails to properly validate memory boundaries during authentication operations. This improper memory access allows attackers to read data beyond the intended buffer boundaries, which can result in two potential outcomes: a denial of service through service crash, or more critically, the ability to bypass authentication mechanisms entirely.

The network-accessible nature of this vulnerability makes it particularly dangerous, as attackers can exploit it remotely without requiring any prior authentication or user interaction. The administration server, which handles privileged operations for the EFT platform, becomes a high-value target when authentication controls can be circumvented.

Root Cause

The root cause of CVE-2023-2989 is improper bounds checking in the administration server's memory handling routines. When processing incoming requests, the server reads memory beyond the allocated buffer boundaries. This out-of-bounds read can expose sensitive memory contents or corrupt the authentication state, allowing attackers to bypass security controls. The vulnerability falls under CWE-125 (Out-of-bounds Read), indicating that the application accesses memory locations outside the intended data structure boundaries.

Attack Vector

The attack vector for this vulnerability is network-based, allowing remote exploitation without authentication. An attacker can send specially crafted requests to the Globalscape EFT administration server that trigger the out-of-bounds memory read condition. The exploitation requires no privileges on the target system and no user interaction, making it highly accessible to remote attackers.

The vulnerability mechanism involves sending malformed input to the administration server that causes it to read beyond allocated memory boundaries. When successful, this can either crash the service (causing denial of service) or manipulate the authentication flow to grant unauthorized access. Technical details and exploitation methodology are available through the Rapid7 security research blog.

Detection Methods for CVE-2023-2989

Indicators of Compromise

• Unexpected crashes or restarts of the Globalscape EFT administration server service
• Anomalous authentication events showing successful logins without corresponding valid credential submissions
• Unusual network traffic patterns targeting the EFT administration server ports
• Administrative actions performed by unrecognized sessions or from unexpected source IP addresses

Detection Strategies

• Monitor EFT administration server logs for authentication anomalies, particularly successful authentications that lack normal credential validation entries
• Implement network-based intrusion detection rules to identify malformed requests targeting the administration server
• Deploy endpoint detection solutions to monitor the EFT server process for abnormal memory access patterns or unexpected crashes
• Audit administrative actions on the EFT platform and correlate with authenticated session records

Monitoring Recommendations

• Enable verbose logging on the Globalscape EFT administration server to capture detailed authentication and session information
• Configure SIEM alerts for EFT administration server service failures or unexpected restarts
• Implement network segmentation monitoring to detect unauthorized access attempts to administration interfaces
• Establish baseline behavior for administration server connections and alert on deviations

How to Mitigate CVE-2023-2989

Immediate Actions Required

• Upgrade Globalscape EFT Server to version 8.1.0.16 or later immediately
• Restrict network access to the EFT administration server to trusted management networks only
• Implement network segmentation to isolate the administration interface from untrusted networks
• Monitor for signs of exploitation while preparing for upgrade

Patch Information

Fortra has released a security update that addresses this vulnerability in Globalscape EFT Server version 8.1.0.16 and later. Organizations should update to the latest available version to ensure protection against this and related vulnerabilities. Detailed patch information and upgrade instructions are available in the Globalscape EFT Vulnerability Advisory.

Workarounds

• Implement strict firewall rules to limit administration server access to specific trusted IP addresses
• Use VPN or jump hosts to access the administration interface rather than exposing it directly to the network
• Enable additional authentication factors where supported to provide defense-in-depth
• Consider temporarily disabling remote administration access until patching is complete if the risk is deemed unacceptable

# Example firewall rule to restrict EFT admin server access (adjust port as needed)
# Only allow administration access from trusted management network
iptables -A INPUT -p tcp --dport 1100 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 1100 -j DROP