peass-ng/PEASS-ng · warning · ArgumentNullException

volumeMountPoint

Error message

volumeMountPoint

What it means

GetVolumeGuid(string volumeMountPoint) throws ArgumentNullException with paramName "volumeMountPoint" when the argument is null, empty, or whitespace. The method converts a mount point or path into its \\?\Volume{GUID}\ unique name and rejects blank input before any native call.

Source

Thrown at winPEAS/winPEASexe/winPEAS/3rdParty/AlphaFS/Device/Volume/Volume.GetVolumeGuid.cs:46

namespace Alphaleonis.Win32.Filesystem
{
   public static partial class Volume
   {
      /// <summary>[AlphaFS] 
      ///   Retrieves a volume <see cref="Guid"/> path for the volume that is associated with the specified volume mount point (drive letter,
      ///   volume GUID path, or mounted folder).
      /// </summary>
      /// <exception cref="ArgumentNullException"/>
      /// <param name="volumeMountPoint">
      ///   The path of a mounted folder (for example, "Y:\MountX\") or a drive letter (for example, "X:\").
      /// </param>
      /// <returns>The unique volume name of the form: "\\?\Volume{GUID}\".</returns>
      [SuppressMessage("Microsoft.Interoperability", "CA1404:CallGetLastErrorImmediatelyAfterPInvoke", Justification = "Marshal.GetLastWin32Error() is manipulated.")]
      [SecurityCritical]
      public static string GetVolumeGuid(string volumeMountPoint)
      {
         if (Utils.IsNullOrWhiteSpace(volumeMountPoint))
            throw new ArgumentNullException("volumeMountPoint");

         // The string must end with a trailing backslash ('\').
         volumeMountPoint = Path.GetFullPathCore(null, false, volumeMountPoint, GetFullPathOptions.AsLongPath | GetFullPathOptions.AddTrailingDirectorySeparator | GetFullPathOptions.FullCheck);

         var volumeGuid = new StringBuilder(100);
         var uniqueName = new StringBuilder(100);

         try
         {
            using (new NativeMethods.ChangeErrorMode(NativeMethods.ErrorMode.FailCriticalErrors))
            {
               // GetVolumeNameForVolumeMountPoint()
               // 2013-07-18: MSDN does not confirm LongPath usage but a Unicode version of this function exists.

               return NativeMethods.GetVolumeNameForVolumeMountPoint(volumeMountPoint, volumeGuid, (uint)volumeGuid.Capacity)

                  // The string must end with a trailing backslash.
                  ? NativeMethods.GetVolumeNameForVolumeMountPoint(Path.AddTrailingDirectorySeparator(volumeGuid.ToString(), false), uniqueName, (uint)uniqueName.Capacity)

View on GitHub (pinned to 53fb989abc)

Solutions

1. Pass a valid path or mount point (e.g. "C:\" or \\?\Volume{GUID}\)
2. Guard the call with string.IsNullOrWhiteSpace and treat blank input as "no volume"
3. Catch ArgumentNullException in enumeration loops over untrusted data

Example fix

// before
bool mounted = Volume.IsVolume(mountPoint);
// after
bool mounted = !string.IsNullOrWhiteSpace(mountPoint) && Volume.IsVolume(mountPoint);

if (string.IsNullOrWhiteSpace(volumeMountPoint)) return null; // no volume to resolve

static bool HasMountPointValue(string s) => !string.IsNullOrWhiteSpace(s);

try { guid = Volume.GetVolumeGuid(mountPoint); }
catch (ArgumentNullException ex) { Log.Warn($"Mount point missing: {ex.ParamName}"); }

When it happens

Trigger: Calling Volume.GetVolumeGuid(null) or ""; passing an uninitialized variable that should have held a mount point path; IsVolume forwarding an empty candidate string.

Common situations: Enumerating mount points where an entry failed to parse; reading mount points from a config/registry that returned empty; calling GetVolumeGuid on a path variable that was never assigned.

Related errors

• volumeGuid
• volumeGuid
• volumePathName
• path
• deviceName

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/1a22e5a84fe09a8d. Report an issue: GitHub.