charencode.py

#!/usr/bin/env python

"""
Copyright (c) 2006-2016 sqlmap developers (http://sqlmap.org/)
See the file 'doc/COPYING' for copying permission
"""

import string

from lib.core.enums import PRIORITY

__priority__ = PRIORITY.LOWEST

def dependencies():
    pass

def tamper(payload, **kwargs):
    """
    Url-encodes all characters in a given payload (not processing already
    encoded)

    Tested against:
        * Microsoft SQL Server 2005
        * MySQL 4, 5.0 and 5.5
        * Oracle 10g
        * PostgreSQL 8.3, 8.4, 9.0

    Notes:
        * Useful to bypass very weak web application firewalls that do not
          url-decode the request before processing it through their ruleset
        * The web server will anyway pass the url-decoded version behind,
          hence it should work against any DBMS

    >>> tamper('SELECT FIELD FROM%20TABLE')
    '%53%45%4C%45%43%54%20%46%49%45%4C%44%20%46%52%4F%4D%20%54%41%42%4C%45'
    """

    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 += payload[i:i + 3]
                i += 3
            else:
                retVal += '%%%.2X' % ord(payload[i])
                i += 1

    return retVal