Sanitize archive entry file name

PowerShell · Oct 24, 2023 · f2d52d0 · f2d52d0
1 parent 5bd8930
commit f2d52d0
Showing 1 changed file with 15 additions and 9 deletions.
diff --git a/src/code/InstallHelper.cs b/src/code/InstallHelper.cs
@@ -1175,19 +1175,25 @@ private bool TryExtractToDirectory(string zipPath, string extractPath, out Error
                 {
                     foreach (ZipArchiveEntry entry in archive.Entries)
                     {
-                        // Sanitize the filename to remove any potentially harmful characters
-                        string sanitizedFileName = Path.GetFileName(entry.FullName);
+                        // Sanitize the filename to remove any potentially harmful characters (ie '..').
+                        if (entry.Name.Equals(".."))
+                        {
+                            error = new ErrorRecord(
+                                new Exception($"Error occured while extracting .nupkg.  File contains a potentially malicious file path."),
+                                "FileNameErrorWhenExtractingNupkg",
+                                ErrorCategory.InvalidArgument,
+                                _cmdletPassedIn);
 
-                        // Create a new entry in the archive
-                        ZipArchiveEntry sanitizedEntry = archive.CreateEntry(sanitizedFileName);
+                            return false;
+                        }
 
                         // If a file has one or more parent directories.
-                        if (sanitizedEntry.FullName.Contains(Path.DirectorySeparatorChar) || sanitizedEntry.FullName.Contains(Path.AltDirectorySeparatorChar))
+                        if (entry.FullName.Contains(Path.DirectorySeparatorChar) || entry.FullName.Contains(Path.AltDirectorySeparatorChar))
                         {
                             // Create the parent directories if they do not already exist
                             var lastPathSeparatorIdx = entry.FullName.Contains(Path.DirectorySeparatorChar) ?
-                                sanitizedEntry.FullName.LastIndexOf(Path.DirectorySeparatorChar) : sanitizedEntry.FullName.LastIndexOf(Path.AltDirectorySeparatorChar);
-                            var parentDirs = sanitizedEntry.FullName.Substring(0, lastPathSeparatorIdx);
+                                entry.FullName.LastIndexOf(Path.DirectorySeparatorChar) : entry.FullName.LastIndexOf(Path.AltDirectorySeparatorChar);
+                            var parentDirs = entry.FullName.Substring(0, lastPathSeparatorIdx);
                             var destinationDirectory = Path.Combine(extractPath, parentDirs);
                             if (!Directory.Exists(destinationDirectory))
                             {
@@ -1196,9 +1202,9 @@ private bool TryExtractToDirectory(string zipPath, string extractPath, out Error
                         }
 
                         // Gets the full path to ensure that relative segments are removed.
-                        string destinationPath = Path.GetFullPath(Path.Combine(extractPath, sanitizedEntry.FullName));
+                        string destinationPath = Path.GetFullPath(Path.Combine(extractPath, entry.FullName));
 
-                        sanitizedEntry.ExtractToFile(destinationPath, overwrite:true);
+                        entry.ExtractToFile(destinationPath, overwrite:true);
                     }
                 }
             }