Patched code sample

import re

# This example focuses on the CVE's description of defeating a path sanitizer
# via a backslash-single-quote sequence to inject SQL.
#
# The vulnerability lies in improperly sanitizing a path string before it's
# embedded within a larger SQL command, such as in DataFrame.to_csv() which
# might generate a COPY command.

def vulnerable_path_sanitizer(path: str) -> str:
    """
    A simplified representation of a vulnerable sanitizer.
    It attempts to escape single quotes, but does not account for backslashes,
    allowing an attacker to craft a payload where a backslash escapes the
    sanitizer's own escape character.
    """
    # A naive replacement that can be bypassed.
    return path.replace("'", "''")

def fixed_path_sanitizer(path: str) -> str:
    """
    A representation of the fix for the path sanitization vulnerability.
    This function correctly escapes both backslashes and single quotes,
    ensuring that the path is treated as a literal string by the SQL engine.
    This prevents the path from prematurely terminating the string literal and
    injecting malicious SQL.
    """
    # 1. First, escape any existing backslashes.
    # 2. Then, escape the single quotes.
    # The order is crucial to prevent the exploit.
    escaped_path = path.replace('\\', '\\\\').replace("'", "\\'")
    return escaped_path

def generate_example_sql(stage_path: str) -> str:
    """
    Simulates the generation of a SQL command using the provided stage path.
    In a real scenario, this might be a COPY INTO command.
    """
    return f"COPY INTO my_table FROM '@~/{stage_path}' FILE_FORMAT=(TYPE=CSV);"

if __name__ == '__main__':
    # Malicious payload designed to break out of the string literal and inject a command.
    # The `\'` is intended to be interpreted by the SQL parser as an escaped quote,
    # allowing the subsequent SQL to be executed.
    malicious_path_payload = "poc.csv\\' ) OR 1=1; -- "

    # --- Vulnerable Scenario ---
    # The sanitizer fails to handle the backslash correctly.
    vulnerable_sanitized_path = vulnerable_path_sanitizer(malicious_path_payload)
    vulnerable_sql = generate_example_sql(vulnerable_sanitized_path)

    # --- Fixed Scenario ---
    # The fixed sanitizer correctly escapes both the backslash and the quote.
    fixed_sanitized_path = fixed_path_sanitizer(malicious_path_payload)
    fixed_sql = generate_example_sql(fixed_sanitized_path)

    print("--- DEMONSTRATION OF THE FIX ---")
    print(f"\n[+] Malicious Payload:\n'{malicious_path_payload}'")

    print("\n[-] VULNERABLE OUTPUT (INCORRECTLY SANITIZED):")
    print("The backslash is preserved, allowing the single quote to terminate the string.")
    print(vulnerable_sql)
    # Expected vulnerable output:
    # COPY INTO my_table FROM '@~/poc.csv\' ) OR 1=1; -- ' FILE_FORMAT=(TYPE=CSV);
    # This is injectable SQL.

    print("\n[+] FIXED OUTPUT (CORRECTLY SANITIZED):")
    print("The backslash and quote are properly escaped, neutralizing the injection.")
    print(fixed_sql)
    # Expected fixed output:
    # COPY INTO my_table FROM '@~/poc.csv\\\' ) OR 1=1; -- ' FILE_FORMAT=(TYPE=CSV);
    # This is treated as a literal (and weird) filename, not an injection.