Smartermail 6919 Exploit -

SmarterMail Build 6919 is affected by a critical Remote Code Execution (RCE) vulnerability, tracked as CVE-2019-7214 , which stems from the deserialization of untrusted data The Core Vulnerability

In version 16.x and builds prior to 6985, SmarterMail exposes three .NET remoting endpoints on TCP port 17001 By default, these endpoints—specifically —are often exposed to the public at tcp://0.0.0.0:17001/Servers

. Because the application fails to properly validate data sent to these endpoints, an unauthenticated attacker can send serialized .NET commands via a TCP socket connection. Impact & Exploitation

Successful exploitation allows an unauthenticated user to execute arbitrary commands with SYSTEM-level privileges

(the highest level of administrative control on a Windows server). Exploit Availability : Public exploit code and a Metasploit module exploit/windows/http/smartermail_rce ) are widely available. Verification smartermail 6919 exploit

: Security researchers confirmed Build 6919 is vulnerable, while Build 6985 effectively mitigated the issue by making port 17001 accessible only locally (127.0.0.1). Exploit-DB Remediation : Immediately upgrade to Build 6985

or later. In newer versions, port 17001 is no longer publicly accessible. Workaround

: If upgrading is not possible, use a firewall to block all external traffic to TCP port 17001. or more information on the newer 2026 vulnerabilities currently being exploited in the wild? SmarterMail Build 6985 - Remote Code Execution - Exploit-DB 9 Dec 2020 —

Remediation and Mitigation

SmarterTools has released a patch to address this vulnerability. Immediate action is required. SmarterMail Build 6919 is affected by a critical

Prerequisites for the Attacker

• A valid user account on the target SmarterMail server (even a low-privilege trial account).
• The target server running an unpatched version (e.g., SmarterMail 15.7.6919 or similar build where the bug was first reported).
• A victim with high privileges (a domain admin or system admin who uses the webmail interface).

How to Confirm If You Have Been Compromised

Search your SmarterMail server for the following IoCs (Indicators of Compromise):

• Unexpected files: Look in C:\inetpub\wwwroot\aspnet_client\ or C:\Program Files (x86)\SmarterTools\SmarterMail\WebRoot\ for .aspx or .ashx files not part of the official distribution. Check timestamps around the time of any service restart.
• Suspicious user accounts: Run SELECT * FROM Users WHERE IsAdmin = 1 against your SmarterMail database (usually a SQLite or MSSQL DB). Look for unknown admin users.
• Outbound connections: Use netstat -ano to see if svchost.exe (or your SmarterMail process) is making outgoing connections to non-mail-related IPs (check Tor exit nodes or known mining pools).
• Log anomalies: Search the Logging\Service Logs folder for the exact phrase 6919. If present alongside a Process.Start event, assume compromise.

The Attack in Action

Imagine a typical SmarterMail server humming along, processing thousands of legitimate email logins. An attacker scans the internet for exposed SmarterMail login portals (usually on port 80, 443, or 9998 for the admin interface).

Using a simple tool like curl or a Python script, the attacker sends a request that looks something like this (simplified for clarity):

POST /interface/Download.aspx?file=../../../Windows/Temp/shell.aspx HTTP/1.1
Host: targetmailserver.com
Content-Type: application/x-www-form-urlencoded
data=<% System.Diagnostics.Process.Start("cmd.exe"); %>
 Remediation and Mitigation SmarterTools has released a patch

This request attempts to navigate up three directories (../../../) from the web root into the Windows temporary folder and write a file called shell.aspx. Because the server fails to validate the path, it complies. The attacker then visits https://targetmailserver.com/Temp/shell.aspx and now has a command prompt on the mail server itself.

Once inside, the attacker can:

• Read every email stored on the server.
• Reset any user’s password.
• Use the server as a launchpad to attack the internal corporate network.
• Install ransomware or data-wiping malware.

Defensive Post-Mortem: Why Your Stack Failed

If you were hit by this, don't blame the vendor entirely. Your defense-in-depth failed here:

• App Whitelisting: If you had AppLocker or WDAC enabled, w3wp.exe would have been blocked from executing cmd.exe. The RCE would have failed.
• Log Monitoring: No SIEM alert fired for "Process started from IIS worker process" because you aren't logging that.
• WAF Placement: Your WAF was inspecting port 443 traffic but not the User-Agent header for C# syntax.