CVE-2020-29548
📋 TL;DR
This vulnerability allows man-in-the-middle attackers to inject plaintext commands into encrypted POP3 sessions in SmarterMail. Attackers can pipeline commands after a STARTTLS command, potentially compromising email security. Organizations running vulnerable versions of SmarterMail are affected.
💻 Affected Systems
- SmarterTools SmarterMail
📦 What is this software?
Smartermail by Smartertools
⚠️ Risk & Real-World Impact
Worst Case
Attackers could intercept and manipulate email communications, steal credentials, access sensitive emails, or compromise the entire email server.
Likely Case
Credential theft and unauthorized access to email accounts, potentially leading to data exfiltration or further network compromise.
If Mitigated
With proper TLS configuration and network segmentation, risk is limited to potential session hijacking within the email service.
🎯 Exploit Status
Requires man-in-the-middle position on network. Exploit tools for STARTTLS command injection are publicly available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 100.0.7538 and later
Vendor Advisory: https://www.smartertools.com/smartermail/release-notes/current
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download and install SmarterMail version 100.0.7538 or later from SmarterTools website. 3. Restart SmarterMail service. 4. Verify patch installation.
🔧 Temporary Workarounds
Disable POP3 STARTTLS
allDisable STARTTLS for POP3 service to prevent command injection
Edit SmarterMail configuration to set POP3 STARTTLS = false
Use POP3S instead
allConfigure POP3 to use implicit TLS (POP3S) on port 995
Configure SmarterMail to use POP3S on port 995 with SSL/TLS
🧯 If You Can't Patch
- Implement strict network segmentation to isolate email servers
- Deploy TLS inspection and monitoring for anomalous POP3 traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check SmarterMail version in admin interface. If version is 100.0.7537 or earlier, system is vulnerable.Check Version:
Check SmarterMail admin dashboard or run: netstat -an | findstr :110 (Windows) or netstat -tlnp | grep :110 (Linux)Verify Fix Applied:
Verify SmarterMail version is 100.0.7538 or later in admin interface. Test POP3 STARTTLS functionality.📡 Detection & Monitoring
Log Indicators:
- Multiple POP3 STARTTLS commands in single session
- Unusual command sequences after STARTTLS
- Failed authentication attempts after STARTTLS
Network Indicators:
- Unusual POP3 traffic patterns
- Multiple commands pipelined after STARTTLS
- Traffic on port 110 with encrypted payloads
SIEM Query:
source="smartermail.log" AND "POP3" AND "STARTTLS" AND command_count > 2