peass-ng/PEASS-ng · warning · ArgumentNullException

deviceName

Error message

deviceName

What it means

QueryDosDevice(string deviceName) throws ArgumentNullException with paramName "deviceName" when the argument is null, empty, or whitespace. It wraps the Win32 QueryDosDevice API to translate an MS-DOS device name (e.g. "C:") into its target device string, and validates input before the native call.

Source

Thrown at winPEAS/winPEASexe/winPEAS/3rdParty/AlphaFS/Device/Volume/Volume.QueryDosDevice.cs:52

      /// <summary>[AlphaFS] Retrieves a sorted list of all existing MS-DOS device names.</summary>
      /// <returns>An <see cref="IEnumerable{String}"/> sorted list of all existing MS-DOS device names.</returns>
      [SecurityCritical]
      public static IEnumerable<string> QueryAllDosDevices()
      {
         return QueryDosDeviceCore(null, true);
      }


      /// <summary>[AlphaFS] Retrieves the current mapping for a particular MS-DOS device name.</summary>
      /// <returns>The current mapping for a particular MS-DOS device name.</returns>
      /// <exception cref="ArgumentNullException"/>
      /// <exception cref="FileNotFoundException"/>
      /// <param name="deviceName">An MS-DOS device name string specifying the target of the query, such as: "C:", "D:" or "\\?\Volume{GUID}".</param>
      [SecurityCritical]
      public static string QueryDosDevice(string deviceName)
      {
         if (Utils.IsNullOrWhiteSpace(deviceName))
            throw new ArgumentNullException("deviceName");


         var devName = QueryDosDeviceCore(deviceName, false).ToArray()[0];

         return !Utils.IsNullOrWhiteSpace(devName) ? devName : null;
      }




      /// <summary>[AlphaFS] Retrieves the current mapping for a particular MS-DOS device name. The function can also obtain a list of all existing MS-DOS device names.</summary>
      /// <returns>An <see cref="IEnumerable{String}"/> sorted list of all existing MS-DOS device names or the .</returns>
      /// <exception cref="ArgumentNullException"/>
      /// <exception cref="FileNotFoundException"/>
      /// <param name="deviceName">An MS-DOS device name string specifying the target of the query, such as: "C:", "D:" or "\\?\Volume{GUID}".</param>
      /// <param name="sort"><c>true</c> to sort the list with MS-DOS device names.</param>
      [SecurityCritical]
      internal static IEnumerable<string> QueryDosDeviceCore(string deviceName, bool sort)

View on GitHub (pinned to 53fb989abc)

Solutions

1. Pass a valid MS-DOS device name such as "C:" or "\\?\Volume{GUID}\"
2. Guard with string.IsNullOrWhiteSpace before calling
3. Catch ArgumentNullException and treat blank device names as unresolved

Example fix

// before
var target = Volume.QueryDosDevice(devName);
// after
var target = string.IsNullOrWhiteSpace(devName) ? null : Volume.QueryDosDevice(devName);

var target = string.IsNullOrWhiteSpace(deviceName) ? null : Volume.QueryDosDevice(deviceName);

static bool IsValidDosDeviceName(string s) => !string.IsNullOrWhiteSpace(s) && (Regex.IsMatch(s, @"^[A-Za-z]:$") || s.StartsWith(@"\\?\Volume{"));

try { target = Volume.QueryDosDevice(devName); }
catch (ArgumentNullException) { Log.Warn($"Device name blank: {devName}"); }

When it happens

Trigger: Calling Volume.QueryDosDevice(null)/"" when looking up a drive mapping; GetVolumeDeviceName passing through an empty device name from a parsed volume entry.

Common situations: Resolving drive letters from a list where some entries are blank; a mount-point parse produced an empty device name; drive-letter variable not initialized.

Related errors

• deviceName
• volumeGuid
• volumeGuid
• volumePathName
• volumeMountPoint

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/5110d73ea7be03c8. Report an issue: GitHub.