hardened agent (added systempaths class to pin paths, no more env_var support for backend api)

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Collectors/DeviceInfoCollector.NetworkAndSecurity.cs

@@ -7,6 +7,7 @@ using System.Net.NetworkInformation;
 using System.Text.Json;
 using System.Threading.Tasks;
 using AutopilotMonitor.Agent.Core.Logging;
+using AutopilotMonitor.Agent.Core.Security;
 using AutopilotMonitor.Shared.Models;
 using Microsoft.Win32;
 
@@ -635,7 +636,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Collectors
             {
                 var psi = new ProcessStartInfo
                 {
-                    FileName = "netsh.exe",
+                    FileName = SystemPaths.Netsh,
                     Arguments = "wlan show interfaces",
                     UseShellExecute = false,
                     RedirectStandardOutput = true,

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Collectors/GatherCollectors/CommandCollector.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Text;
+using AutopilotMonitor.Agent.Core.Security;
 using AutopilotMonitor.Shared.Models;
 
 namespace AutopilotMonitor.Agent.Core.Monitoring.Collectors.GatherCollectors
@@ -56,7 +57,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Collectors.GatherCollectors
                     var encodedCommand = Convert.ToBase64String(Encoding.Unicode.GetBytes(command));
                     psi = new ProcessStartInfo
                     {
-                        FileName = "powershell.exe",
+                        FileName = SystemPaths.PowerShell,
                         Arguments = $"-NoProfile -ExecutionPolicy RemoteSigned -EncodedCommand {encodedCommand}",
                         UseShellExecute = false,
                         RedirectStandardOutput = true,
@@ -68,7 +69,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Collectors.GatherCollectors
                 {
                     psi = new ProcessStartInfo
                     {
-                        FileName = "cmd.exe",
+                        FileName = SystemPaths.Cmd,
                         Arguments = $"/c {command}",
                         UseShellExecute = false,
                         RedirectStandardOutput = true,

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Collectors/NetworkChangeDetector.cs

@@ -8,6 +8,7 @@ using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
 using AutopilotMonitor.Agent.Core.Logging;
+using AutopilotMonitor.Agent.Core.Security;
 using AutopilotMonitor.Shared;
 using AutopilotMonitor.Shared.Models;
 
@@ -401,7 +402,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Collectors
             {
                 var psi = new ProcessStartInfo
                 {
-                    FileName = "netsh.exe",
+                    FileName = SystemPaths.Netsh,
                     Arguments = "wlan show interfaces",
                     UseShellExecute = false,
                     RedirectStandardOutput = true,

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Core/CleanupService.cs

@@ -3,6 +3,7 @@ using System.Diagnostics;
 using System.IO;
 using AutopilotMonitor.Agent.Core.Configuration;
 using AutopilotMonitor.Agent.Core.Logging;
+using AutopilotMonitor.Agent.Core.Security;
 
 namespace AutopilotMonitor.Agent.Core.Monitoring.Core
 {
@@ -101,8 +102,10 @@ Remove-Item -Path $scriptPath -Force -ErrorAction SilentlyContinue
                 // creates a new process group that breaks job inheritance, even under SYSTEM.
                 var psi = new ProcessStartInfo
                 {
-                    FileName = "cmd.exe",
-                    Arguments = $"/c start \"\" /b powershell.exe -NoProfile -ExecutionPolicy Bypass -WindowStyle Hidden -File \"{tempScriptPath}\"",
+                    FileName = SystemPaths.Cmd,
+                    // Absolute path to powershell.exe is passed to `start` to prevent PATH hijacking
+                    // (the `start` builtin does its own PATH resolution for the target command).
+                    Arguments = $"/c start \"\" /b \"{SystemPaths.PowerShell}\" -NoProfile -ExecutionPolicy Bypass -WindowStyle Hidden -File \"{tempScriptPath}\"",
                     UseShellExecute = false,
                     CreateNoWindow = true,
                     WorkingDirectory = Path.GetTempPath()

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Core/MonitoringService.EventUpload.cs

@@ -12,6 +12,7 @@ using AutopilotMonitor.Agent.Core.Logging;
 using AutopilotMonitor.Agent.Core.Monitoring.Collectors;
 using AutopilotMonitor.Agent.Core.Monitoring.Network;
 using AutopilotMonitor.Agent.Core.Monitoring.Tracking;
+using AutopilotMonitor.Agent.Core.Security;
 using AutopilotMonitor.Shared;
 using AutopilotMonitor.Shared.Models;
 
@@ -635,7 +636,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Core
 
                     var psi = new ProcessStartInfo
                     {
-                        FileName = "shutdown.exe",
+                        FileName = SystemPaths.Shutdown,
                         Arguments = $"/r /t {_configuration.RebootDelaySeconds} /c \"Autopilot enrollment completed - rebooting\"",
                         UseShellExecute = false,
                         CreateNoWindow = true

src/Agent/AutopilotMonitor.Agent.Core/Monitoring/Network/TimezoneService.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using AutopilotMonitor.Agent.Core.Logging;
+using AutopilotMonitor.Agent.Core.Security;
 
 namespace AutopilotMonitor.Agent.Core.Monitoring.Network
 {
@@ -50,7 +51,7 @@ namespace AutopilotMonitor.Agent.Core.Monitoring.Network
 
                 var psi = new ProcessStartInfo
                 {
-                    FileName = "tzutil",
+                    FileName = SystemPaths.TzUtil,
                     Arguments = $"/s \"{windowsId}\"",
                     UseShellExecute = false,
                     RedirectStandardOutput = true,

src/Agent/AutopilotMonitor.Agent.Core/Security/SystemPaths.cs

@@ -0,0 +1,48 @@
+using System;
+using System.IO;
+
+namespace AutopilotMonitor.Agent.Core.Security
+{
+    /// <summary>
+    /// Resolved absolute paths to Windows system binaries.
+    ///
+    /// Rationale: launching processes by bare name (e.g. "cmd.exe", "tzutil") lets
+    /// Windows walk the PATH to find them. As SYSTEM this is a DLL/binary-hijacking
+    /// vector — an attacker able to plant a file in any PATH entry ahead of System32
+    /// gets code execution with SYSTEM privileges. Always use these resolved paths.
+    ///
+    /// <see cref="Environment.SystemDirectory"/> respects WOW64 redirection
+    /// automatically:
+    ///   - 64-bit process on any Windows → C:\Windows\System32
+    ///   - 32-bit process on 64-bit Windows → C:\Windows\SysWOW64
+    /// The agent ships as AnyCPU/net48 and runs 64-bit on 64-bit Windows, so this
+    /// resolves to the real System32. It also honors non-default %SystemRoot%
+    /// (rare, but seen in custom OEM images on drives other than C:).
+    ///
+    /// All listed binaries are in-box on every supported Windows version
+    /// (Windows 7 / 8.1 / 10 / 11 / Server 2012R2 – 2025).
+    /// </summary>
+    public static class SystemPaths
+    {
+        private static readonly string System32 = Environment.SystemDirectory;
+
+        /// <summary>C:\Windows\System32\cmd.exe</summary>
+        public static readonly string Cmd = Path.Combine(System32, "cmd.exe");
+
+        /// <summary>C:\Windows\System32\shutdown.exe</summary>
+        public static readonly string Shutdown = Path.Combine(System32, "shutdown.exe");
+
+        /// <summary>C:\Windows\System32\tzutil.exe</summary>
+        public static readonly string TzUtil = Path.Combine(System32, "tzutil.exe");
+
+        /// <summary>C:\Windows\System32\netsh.exe</summary>
+        public static readonly string Netsh = Path.Combine(System32, "netsh.exe");
+
+        /// <summary>
+        /// C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
+        /// Note: the "v1.0" folder is historical — it hosts every in-box PowerShell
+        /// version including 5.1 on Windows 10/11. Do not "fix" it to v5.1.
+        /// </summary>
+        public static readonly string PowerShell = Path.Combine(System32, "WindowsPowerShell", "v1.0", "powershell.exe");
+    }
+}

src/Agent/AutopilotMonitor.Agent/Program.Configuration.cs

@@ -105,9 +105,7 @@ namespace AutopilotMonitor.Agent
             bool   enableGeoLocationConfig = true;
             bool   useClientCertAuthConfig = true;
 
-            // Environment variable overrides built-in default
-            apiBaseUrl = Environment.GetEnvironmentVariable("AUTOPILOT_MONITOR_API") ?? apiBaseUrl;
-            // CLI override wins over environment variable/default
+            // CLI override wins over built-in default
             if (!string.IsNullOrWhiteSpace(apiBaseUrlOverride))
                 apiBaseUrl = apiBaseUrlOverride;
 

src/Agent/AutopilotMonitor.Agent/SelfUpdater.cs

@@ -6,6 +6,7 @@ using System.Net.Http;
 using System.Security.Cryptography;
 using System.Text;
 using System.Threading.Tasks;
+using AutopilotMonitor.Agent.Core.Security;
 using AutopilotMonitor.Shared;
 using Newtonsoft.Json.Linq;
 
@@ -451,7 +452,7 @@ namespace AutopilotMonitor.Agent
 
             var psi = new ProcessStartInfo
             {
-                FileName = "powershell.exe",
+                FileName = SystemPaths.PowerShell,
                 Arguments = $"-NoProfile -NonInteractive -EncodedCommand {encoded}",
                 WindowStyle = ProcessWindowStyle.Hidden,
                 CreateNoWindow = true,

src/Agent/AutopilotMonitor.Agent/buildcounter.txt

@@ -1 +1 @@
-885
+887