CVE-2023-43902
📋 TL;DR
This vulnerability allows unauthenticated attackers to bypass password reset controls in EMSigner v2.8.7, enabling them to access any user account including administrator accounts. All organizations using the vulnerable version are affected, potentially leading to complete system compromise.
💻 Affected Systems
- EMSigner
📦 What is this software?
Emsigner by Emsigner
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover where attackers gain administrative access, steal sensitive data, deploy ransomware, or maintain persistent access to the entire environment.
Likely Case
Attackers gain unauthorized access to user accounts, potentially escalating to administrative privileges to modify configurations, access sensitive documents, or deploy malware.
If Mitigated
With proper network segmentation and monitoring, impact could be limited to the EMSigner application itself, though account compromise would still occur.
🎯 Exploit Status
The vulnerability requires crafting a password reset token but does not require authentication, making exploitation straightforward for attackers with basic web application knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.8.8 or later
Vendor Advisory: https://secpro.llc/emsigner-cve-2/
Restart Required: Yes
Instructions:
1. Download the latest version from the official EMSigner vendor site
2. Backup current installation and data
3. Install the updated version following vendor documentation
4. Restart the EMSigner service
5. Verify the fix by testing password reset functionality
🔧 Temporary Workarounds
Disable Password Reset Function
allTemporarily disable the Forgot Your Password functionality to prevent exploitation
# Modify application configuration to disable password reset
# Consult EMSigner documentation for specific configuration changes
Network Access Restriction
linuxRestrict access to EMSigner to trusted IP addresses only
# Example firewall rule (Linux iptables)
iptables -A INPUT -p tcp --dport [EMSIGNER_PORT] -s [TRUSTED_IP] -j ACCEPT
iptables -A INPUT -p tcp --dport [EMSIGNER_PORT] -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate EMSigner from critical systems
- Enable detailed logging and monitoring for password reset attempts and implement alerting for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check if EMSigner version is 2.8.7 by reviewing application version in admin panel or configuration filesCheck Version:
Check EMSigner admin dashboard or configuration files for version informationVerify Fix Applied:
After patching, attempt to trigger the vulnerability by testing password reset functionality with invalid tokens to ensure proper validation📡 Detection & Monitoring
Log Indicators:
- Multiple failed password reset attempts from single IP
- Successful password resets for multiple accounts in short timeframe
- Password reset attempts with unusual token patterns
Network Indicators:
- Unusual traffic patterns to password reset endpoints
- Requests to password reset functionality from unexpected IP ranges
SIEM Query:
source="emsigner" AND (event="password_reset" OR event="forgot_password") AND status="success" | stats count by src_ip, user