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# Copyright (C) 2014-2018 Greenbone Networks GmbH |
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# |
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# SPDX-License-Identifier: GPL-2.0-or-later |
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# |
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# This program is free software; you can redistribute it and/or |
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# modify it under the terms of the GNU General Public License |
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# as published by the Free Software Foundation; either version 2 |
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# of the License, or (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with this program; if not, write to the Free Software |
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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""" Common Vulnerability Scoring System handling class. """ |
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import math |
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cvss_v2_metrics = { |
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'AV': {'L': 0.395, 'A': 0.646, 'N': 1.0}, |
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'AC': {'H': 0.35 , 'M': 0.61, 'L': 0.71}, |
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'Au': {'M': 0.45, 'S': 0.56, 'N': 0.704}, |
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'C': {'N': 0.0, 'P': 0.275, 'C': 0.660}, |
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'I': {'N': 0.0, 'P': 0.275, 'C': 0.660}, |
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'A': {'N': 0.0, 'P': 0.275, 'C': 0.660}, |
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} |
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cvss_v3_metrics = { |
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'AV': {'N': 0.85, 'A': 0.62, 'L': 0.55, 'P': 0.2}, |
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'AC': {'L': 0.77, 'H': 0.44}, |
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'PR_SU': {'N': 0.85, 'L': 0.62, 'H': 0.27}, |
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'PR_SC': {'N': 0.85, 'L': 0.68, 'H': 0.50}, |
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'UI': {'N': 0.85, 'R': 0.62}, |
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'S': {'U': False, 'C': True}, |
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'C': {'H': 0.56, 'L': 0.22, 'N': 0}, |
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'I': {'H': 0.56, 'L': 0.22, 'N': 0}, |
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'A': {'H': 0.56, 'L': 0.22, 'N': 0}, |
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} |
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View Code Duplication |
class CVSS(object): |
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""" Handle cvss vectors and calculate the cvss scoring""" |
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@staticmethod |
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def roundup(value): |
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"""It rounds up to 1 decimal. """ |
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return math.ceil(value * 10) / 10 |
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@staticmethod |
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def _parse_cvss_base_vector(cvss_vector): |
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"""Parse a string containing a cvss base vector. |
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Arguments: |
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cvss_vector (str): cvss base vector to be parsed. |
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Return list with the string values of each vector element. |
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""" |
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vector_as_list = cvss_vector.split('/') |
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return [item.split(':')[1] for item in vector_as_list] |
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@classmethod |
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def cvss_base_v2_value(cls, cvss_base_vector): |
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""" Calculate the cvss base score from a cvss base vector |
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for cvss version 2. |
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Arguments: |
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cvss_base_vector (str) Cvss base vector v2. |
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Return the calculated score |
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""" |
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if not cvss_base_vector: |
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return None |
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_av, _ac, _au, _c, _i, _a = cls._parse_cvss_base_vector( |
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cvss_base_vector) |
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_impact = 10.41 * (1 - (1 - cvss_v2_metrics['C'].get(_c)) * |
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(1 - cvss_v2_metrics['I'].get(_i)) * |
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(1 - cvss_v2_metrics['A'].get(_a))) |
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_exploitability = (20 * cvss_v2_metrics['AV'].get(_av) * |
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cvss_v2_metrics['AC'].get(_ac) * |
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cvss_v2_metrics['Au'].get(_au)) |
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f_impact = 0 if _impact == 0 else 1.176 |
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cvss_base = ((0.6 * _impact) + (0.4 * _exploitability) - 1.5) * f_impact |
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return round(cvss_base, 1) |
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@classmethod |
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def cvss_base_v3_value(cls, cvss_base_vector): |
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""" Calculate the cvss base score from a cvss base vector |
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for cvss version 3. |
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Arguments: |
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cvss_base_vector (str) Cvss base vector v3. |
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Return the calculated score, None on fail. |
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""" |
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if not cvss_base_vector: |
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return None |
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_ver, _av, _ac, _pr, _ui, _s, _c, _i, _a = cls._parse_cvss_base_vector( |
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cvss_base_vector) |
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scope_changed = cvss_v3_metrics['S'].get(_s) |
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isc_base = 1 - ( |
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(1 - cvss_v3_metrics['C'].get(_c)) * |
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(1 - cvss_v3_metrics['I'].get(_i)) * |
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(1 - cvss_v3_metrics['A'].get(_a)) |
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) |
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if scope_changed: |
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_priv_req = cvss_v3_metrics['PR_SC'].get(_pr) |
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else: |
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_priv_req = cvss_v3_metrics['PR_SU'].get(_pr) |
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_exploitability = ( |
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8.22 * |
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cvss_v3_metrics['AV'].get(_av) * |
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cvss_v3_metrics['AC'].get(_ac) * |
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_priv_req * |
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cvss_v3_metrics['UI'].get(_ui) |
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) |
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if scope_changed: |
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_impact = (7.52 * (isc_base - 0.029) - |
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3.25 * pow(isc_base - 0.02, 15)) |
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_base_score = min (1.08 * (_impact + _exploitability), 10) |
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else: |
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_impact = 6.42 * isc_base |
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_base_score = min (_impact + _exploitability, 10) |
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if _impact > 0 : |
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return cls.roundup(_base_score) |
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return 0 |
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greenbone /
ospd
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