chardoubleencode.py

#!/usr/bin/env python

"""
Copyright (c) 2006-2025 sqlmap developers (https://sqlmap.org)
See the file 'LICENSE' for copying permission
"""

import string

from lib.core.enums import PRIORITY

__priority__ = PRIORITY.LOW

def dependencies():
    pass

def tamper(payload, **kwargs):
    """
    Double URL-encodes each character in the payload (ignores already encoded ones) (e.g. SELECT -> %2553%2545%254C%2545%2543%2554)

    Notes:
        * Useful to bypass some weak web application firewalls that do not double URL-decode the request before processing it through their ruleset

    >>> tamper('SELECT FIELD FROM%20TABLE')
    '%2553%2545%254C%2545%2543%2554%2520%2546%2549%2545%254C%2544%2520%2546%2552%254F%254D%2520%2554%2541%2542%254C%2545'
    """

    retVal = payload

    if payload:
        retVal = ""
        i = 0

        while i < len(payload):
            if payload[i] == '%' and (i < len(payload) - 2) and payload[i + 1:i + 2] in string.hexdigits and payload[i + 2:i + 3] in string.hexdigits:
                retVal += '%%25%s' % payload[i + 1:i + 3]
                i += 3
            else:
                retVal += '%%25%.2X' % ord(payload[i])
                i += 1

    return retVal