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NaxsiRules.__validate_genericstr()   B

Complexity

Conditions 6

Size

Total Lines 12

Duplication

Lines 0
Ratio 0 %

Code Coverage

Tests 8
CRAP Score 6.288
Metric Value
cc 6
dl 0
loc 12
ccs 8
cts 10
cp 0.8
crap 6.288
rs 8
1 1
from time import strftime, localtime
2 1
import logging
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3
4 1
from spike.model import db
5 1
from shlex import shlex
6
7
8 1
class NaxsiRules(db.Model):
9 1
    __bind_key__ = 'rules'
10 1
    __tablename__ = 'naxsi_rules'
11
12 1
    id = db.Column(db.Integer, primary_key=True)
13 1
    msg = db.Column(db.String(), nullable=False)
14 1
    detection = db.Column(db.String(1024), nullable=False)
15 1
    mz = db.Column(db.String(1024), nullable=False)
16 1
    score = db.Column(db.String(1024), nullable=False)
17 1
    sid = db.Column(db.Integer, nullable=False, unique=True)
18 1
    ruleset = db.Column(db.String(1024), nullable=False)
19 1
    rmks = db.Column(db.Text, nullable=True, server_default="")
20 1
    active = db.Column(db.Integer, nullable=False, server_default="1")
21 1
    negative = db.Column(db.Integer, nullable=False, server_default='0')
22 1
    timestamp = db.Column(db.Integer, nullable=False)
23
24 1
    mr_kw = ["MainRule", "BasicRule", "main_rule", "basic_rule"]
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    static_mz = {"$ARGS_VAR", "$BODY_VAR", "$URL", "$HEADERS_VAR"}
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    full_zones = {"ARGS", "BODY", "URL", "HEADERS", "FILE_EXT", "RAW_BODY"}
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    rx_mz = {"$ARGS_VAR_X", "$BODY_VAR_X", "$URL_X", "$HEADERS_VAR_X"}
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    sub_mz = list(static_mz) + list(full_zones) + list(rx_mz)
29
30 1
    def __init__(self, msg="", detection="", mz="", score="", sid=42000, ruleset="", rmks="", active=0, negative=0, timestamp=0):
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31 1
        self.msg = msg
32 1
        self.detection = detection
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        self.mz = mz
34 1
        self.score = score
35 1
        self.sid = sid
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        self.ruleset = ruleset
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        self.rmks = rmks
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        self.active = active
39 1
        self.negative = 1 if negative == 'checked' else 0
40 1
        self.timestamp = timestamp
41 1
        self.warnings = []
42 1
        self.error = []
43
44 1
    def fullstr(self):
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        rdate = strftime("%F - %H:%M", localtime(float(str(self.timestamp))))
46 1
        rmks = "# ".join(self.rmks.strip().split("\n"))
47 1
        return "#\n# sid: {0} | date: {1}\n#\n# {2}\n#\n{3}".format(self.sid, rdate, rmks, self.__str__())
48
49 1
    def __str__(self):
50 1
        negate = 'negative' if self.negative == 1 else ''
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        return 'MainRule {} "{}" "msg:{}" "mz:{}" "s:{}" id:{} ;'.format(
52
            negate, self.detection, self.msg, self.mz, self.score, self.sid)
53
54 1
    def explanation(self):
55
        """ Return a string explainign a rule """
56 1
        assoc = {'ARGS': 'argument', 'BODY': 'body', 'URL': 'url', 'HEADER': 'header'}
57 1
        expl = 'The rule number <strong>%d</strong> is ' % self.sid
58 1
        if self.negative:
59
            expl += '<strong>not</strong> '
60 1
        expl += 'setting the '
61 1
        scores = []
62 1
        for score in self.score.split(','):
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            scores.append('<strong>{0}</strong> to <strong>{1}</strong> '.format(*score.split(':', 3)))
64 1
        expl += ', '.join(scores) + 'when it '
65 1
        if self.detection.startswith('str:'):
66 1
            expl += 'finds the string <strong>{}</strong> '.format(self.detection[4:])
67
        else:
68
            expl += 'matches the regexp <strong>{}</strong> '.format(self.detection[3:])
69 1
70 1
        zones = []
71 1
        for mz in self.mz.split('|'):
72 1
            if mz.startswith('$'):
73
                zone,arg = mz.split(":")
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zone,arg = mz.split(":")
^
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74
                for tmpzone in assoc:
75
                    if tmpzone in zone:
76
                        zone_name = assoc[tmpzone]
77
                if "$URL" in zone:
78 1
                    expl += "on the URL {} '{}' ".format("matching regex" if zone == "$URL_X" else "",
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                                                          arg)
80
                else:
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                    expl += "in the var with name {} '{}' of {} ".format("matching regex" if zone.endswith("_X") else "",
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82 1
                                                                  arg, zone_name)
83 1
            else:
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                zones.append('the <strong>{0}</strong>'.format(assoc[mz]))
85
        return expl
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87
    def validate(self):
88 1
        self.__validate_matchzone(self.mz)
89
        self.__validate_id(self.sid)
90
        self.__validate_detection(self.detection)
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92 1
        if not self.msg:
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            self.warnings.append("Rule has no 'msg:'.")
94
        if not self.score:
95
            self.error.append("Rule has no score.")
96 1
97 1
    def __fail(self, msg):
98
        self.error.append(msg)
99 1
        return False
100 1
101 1
    # Bellow are parsers for specific parts of a rule
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103 1
    def __validate_detection(self, p_str, label="", assign=False):
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        p_str = label + p_str
105
        if not p_str.islower():
106 1
            self.warnings.append("detection {} is not lower-case. naxsi is case-insensitive".format(p_str))
107
        if assign is False:
108 1
            return True
109 1
        if p_str.startswith("str:") or p_str.startswith("rx:"):
110
            self.detection = p_str
111 1
        else:
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            return self.__fail("detection {} is neither rx: or str:".format(p_str))
113 1
114 1
        return True
115 1
116 1
    def __validate_genericstr(self, p_str, label="", assign=False):
117 1
        if assign is False:
118 1
            return True
119 1
        if label == "s:":
120 1
            self.score = p_str
121
        elif label == "msg:":
122 1
            self.msg = p_str
123
        elif label == "negative":
124 1
            self.negative = 1
125
        elif label != "":
126 1
            return self.__fail("Unknown fragment {}".format(label+p_str))
127
        return True
128 1
129 1
    def __validate_matchzone(self, p_str, label="", assign=False):
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130
        has_zone = False
131 1
        mz_state = set()
132 1
        locs = p_str.split('|')
133
        for loc in locs:
134 1
            keyword, arg = loc, None
135 1
            if loc.startswith("$"):
136 1
                if loc.find(":") == -1:
137
                    return self.__fail("Missing 2nd part after ':' in {0}".format(loc))
138 1
                keyword, arg = loc.split(":")
139 1
            # check it is a valid keyword
140 1
            if keyword not in self.sub_mz:
141
                return self.__fail("'{0}' no a known sub-part of mz : {1}".format(keyword, self.sub_mz))
142 1
            mz_state.add(keyword)
143 1
            # verify the rule doesn't attempt to target REGEX and STATIC _VAR/URL at the same time
144 1
            if len(self.rx_mz & mz_state) and len(self.static_mz & mz_state):
145 1
                return self.__fail("You can't mix static $* with regex $*_X ({})".format(', '.join(mz_state)))
146 1
            # just a gentle reminder
147
            if arg and arg.islower() is False:
148
                self.warnings.append("{0} in {1} is not lowercase. naxsi is case-insensitive".format(arg, loc))
149
            # the rule targets an actual zone
150 1
            if keyword not in ["$URL", "$URL_X"] and keyword in (self.rx_mz | self.full_zones | self.static_mz):
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151 1
                has_zone = True
152 1
        if has_zone is False:
153
            return self.__fail("The rule/whitelist doesn't target any zone.")
154 1
        if assign is True:
155
            self.mz = p_str
156 1
        return True
157 1
158 1
    def __validate_id(self, p_str, label="", assign=False):
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159 1
        try:
160
            num = int(p_str)
161 1
            if num < 10000:
162
                self.warnings.append("rule IDs below 10k are reserved ({0})".format(num))
163
        except ValueError:
164
            self.error.append("id:{0} is not numeric".format(p_str))
165
            return False
166
        if assign is True:
167 1
            self.sid = num
168 1
        return True
169
170 1
    @staticmethod
171
    def splitter(s):
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172
        lexer = shlex(s)
173 1
        lexer.whitespace_split = True
174 1
        items = list(iter(lexer.get_token, ''))
175 1
        return items
176
177 1
    def parse_rule(self, full_str):
178
        """
179 1
        Parse and validate a full naxsi rule
180
        :param full_str: raw rule
181
        :return: [True|False, dict]
182 1
        """
183
        self.warnings = []
184 1
        self.error = []
185 1
186
        func_map = {"id:": self.__validate_id, "str:": self.__validate_detection,
187 1
                    "rx:": self.__validate_detection, "msg:": self.__validate_genericstr, "mz:": self.__validate_matchzone,
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188 1
                    "negative": self.__validate_genericstr, "s:": self.__validate_genericstr}
189 1
        ret = False
190 1
        split = self.splitter(full_str)  # parse string
191
        intersection = set(split).intersection(set(self.mr_kw))
192 1
193 1
        if not intersection:
194 1
            return self.__fail("No mainrule/basicrule keyword.")
195 1
        elif len(intersection) > 1:
196 1
            return self.__fail("Multiple mainrule/basicrule keywords.")
197 1
198 1
        split.remove(intersection.pop())  # remove the mainrule/basicrule keyword
199
200 1
        if ";" in split:
201 1
            split.remove(";")
202 1
203
        while split:  # iterate while there is data, as handlers can defer
204 1
            for keyword in split:
205 1
                orig_kw = keyword
206
                keyword = keyword.strip()
207 1
208
                if keyword.endswith(";"):  # remove semi-colons
209 1
                    keyword = keyword[:-1]
210
                if keyword.startswith(('"', "'")) and (keyword[0] == keyword[-1]):  # remove (double-)quotes
211
                    keyword = keyword[1:-1]
212
                for frag_kw in func_map:
213
                    ret = False
214
                    if keyword.startswith(frag_kw):
215
                        # parser funcs returns True/False
216
                        ret = func_map[frag_kw](keyword[len(frag_kw):], label=frag_kw, assign=True)
217
                        if ret is True:
218
                            split.remove(orig_kw)
219
                        else:
220
                            return self.__fail("parsing of element '{0}' failed.".format(keyword))
221
                        break
222
                # we have an item that wasn't successfully parsed
223
                if orig_kw in split and ret is not None:
224
                    return False
225
        return True
226