CVE-2018-18912
📋 TL;DR
CVE-2018-18912 is a critical stack-based buffer overflow vulnerability in Easy File Sharing Web Server 7.2 that allows remote attackers to execute arbitrary code by sending a malicious POST request to forum.ghp when creating a new forum topic. This affects organizations running the vulnerable EFS Web Server version, potentially exposing them to complete system compromise.
💻 Affected Systems
- Easy File Sharing Web Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full system control, installs malware, steals data, and establishes persistent access to the server and potentially the entire network.
Likely Case
Attackers exploit the vulnerability to deploy ransomware, cryptocurrency miners, or backdoors, leading to data loss, service disruption, and financial damage.
If Mitigated
With proper network segmentation and intrusion prevention, exploitation attempts are blocked, limiting impact to isolated systems.
🎯 Exploit Status
Multiple public exploit scripts are available, making this easily weaponizable by attackers with minimal technical skill.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Upgrade to a newer version if available from the vendor. 2. If no patch exists, consider migrating to alternative file sharing software.
🔧 Temporary Workarounds
Disable Forum Functionality
windowsRemove or disable the forum.ghp file to prevent exploitation via the vulnerable endpoint.
Move or rename forum.ghp in the EFS Web Server directory
Network Access Control
windowsRestrict access to the EFS Web Server using firewall rules to only trusted IP addresses.
Windows Firewall: New-InboundFirewallRule -DisplayName 'Block EFS' -Direction Inbound -Protocol TCP -LocalPort 80,443 -Action Block
🧯 If You Can't Patch
- Immediately isolate the affected server from the internet and critical internal networks.
- Implement strict network monitoring and intrusion detection for any remaining access to the server.
🔍 How to Verify
Check if Vulnerable:
Check if Easy File Sharing Web Server version 7.2 is installed and running. Look for the forum.ghp file in the installation directory.Check Version:
Check the application interface or installation directory for version information (typically in about dialog or readme files).Verify Fix Applied:
Verify that forum.ghp has been removed/disabled or that the server has been upgraded to a non-vulnerable version.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to forum.ghp with large payloads
- Error logs showing buffer overflow or crash in EFS Web Server process
Network Indicators:
- HTTP POST requests to /forum.ghp with abnormal length or patterns
- Traffic spikes to the EFS Web Server port (default 80/443)
SIEM Query:
source="efs_web_server.log" AND (url="/forum.ghp" AND method="POST" AND size>10000)