#!/usr/bin/env python3
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# Copyright (C) 2009 by Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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# Copyright (C) 2020 by Gregory CLEMENT <gregory.clement@bootlin.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (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 GNU
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# 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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import datetime
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import os
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import requests # URL checking
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import distutils.version
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import time
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import gzip
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import sys
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import operator
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try:
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import ijson
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# backend is a module in < 2.5, a string in >= 2.5
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if 'python' in getattr(ijson.backend, '__name__', ijson.backend):
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try:
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import ijson.backends.yajl2_cffi as ijson
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except ImportError:
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sys.stderr.write('Warning: Using slow ijson python backend\n')
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except ImportError:
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sys.stderr.write("You need ijson to parse NVD for CVE check\n")
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exit(1)
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sys.path.append('utils/')
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NVD_START_YEAR = 2002
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NVD_JSON_VERSION = "1.1"
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NVD_BASE_URL = "https://nvd.nist.gov/feeds/json/cve/" + NVD_JSON_VERSION
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ops = {
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'>=': operator.ge,
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'>': operator.gt,
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'<=': operator.le,
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'<': operator.lt,
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'=': operator.eq
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}
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# Check if two CPE IDs match each other
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def cpe_matches(cpe1, cpe2):
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cpe1_elems = cpe1.split(":")
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cpe2_elems = cpe2.split(":")
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remains = filter(lambda x: x[0] not in ["*", "-"] and x[1] not in ["*", "-"] and x[0] != x[1],
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zip(cpe1_elems, cpe2_elems))
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return len(list(remains)) == 0
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def cpe_product(cpe):
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return cpe.split(':')[4]
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def cpe_version(cpe):
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return cpe.split(':')[5]
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class CVE:
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"""An accessor class for CVE Items in NVD files"""
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CVE_AFFECTS = 1
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CVE_DOESNT_AFFECT = 2
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CVE_UNKNOWN = 3
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def __init__(self, nvd_cve):
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"""Initialize a CVE from its NVD JSON representation"""
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self.nvd_cve = nvd_cve
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@staticmethod
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def download_nvd_year(nvd_path, year):
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metaf = "nvdcve-%s-%s.meta" % (NVD_JSON_VERSION, year)
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path_metaf = os.path.join(nvd_path, metaf)
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jsonf_gz = "nvdcve-%s-%s.json.gz" % (NVD_JSON_VERSION, year)
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path_jsonf_gz = os.path.join(nvd_path, jsonf_gz)
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# If the database file is less than a day old, we assume the NVD data
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# locally available is recent enough.
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if os.path.exists(path_jsonf_gz) and os.stat(path_jsonf_gz).st_mtime >= time.time() - 86400:
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return path_jsonf_gz
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# If not, we download the meta file
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url = "%s/%s" % (NVD_BASE_URL, metaf)
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print("Getting %s" % url)
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page_meta = requests.get(url)
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page_meta.raise_for_status()
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# If the meta file already existed, we compare the existing
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# one with the data newly downloaded. If they are different,
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# we need to re-download the database.
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# If the database does not exist locally, we need to redownload it in
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# any case.
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if os.path.exists(path_metaf) and os.path.exists(path_jsonf_gz):
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meta_known = open(path_metaf, "r").read()
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if page_meta.text == meta_known:
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return path_jsonf_gz
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# Grab the compressed JSON NVD, and write files to disk
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url = "%s/%s" % (NVD_BASE_URL, jsonf_gz)
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print("Getting %s" % url)
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page_json = requests.get(url)
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page_json.raise_for_status()
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open(path_jsonf_gz, "wb").write(page_json.content)
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open(path_metaf, "w").write(page_meta.text)
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return path_jsonf_gz
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@classmethod
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def read_nvd_dir(cls, nvd_dir):
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"""
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Iterate over all the CVEs contained in NIST Vulnerability Database
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feeds since NVD_START_YEAR. If the files are missing or outdated in
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nvd_dir, a fresh copy will be downloaded, and kept in .json.gz
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"""
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for year in range(NVD_START_YEAR, datetime.datetime.now().year + 1):
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filename = CVE.download_nvd_year(nvd_dir, year)
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try:
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content = ijson.items(gzip.GzipFile(filename), 'CVE_Items.item')
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except: # noqa: E722
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print("ERROR: cannot read %s. Please remove the file then rerun this script" % filename)
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raise
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for cve in content:
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yield cls(cve)
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def each_product(self):
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"""Iterate over each product section of this cve"""
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for vendor in self.nvd_cve['cve']['affects']['vendor']['vendor_data']:
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for product in vendor['product']['product_data']:
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yield product
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def parse_node(self, node):
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"""
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Parse the node inside the configurations section to extract the
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cpe information usefull to know if a product is affected by
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the CVE. Actually only the product name and the version
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descriptor are needed, but we also provide the vendor name.
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"""
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# The node containing the cpe entries matching the CVE can also
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# contain sub-nodes, so we need to manage it.
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for child in node.get('children', ()):
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for parsed_node in self.parse_node(child):
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yield parsed_node
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for cpe in node.get('cpe_match', ()):
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if not cpe['vulnerable']:
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return
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product = cpe_product(cpe['cpe23Uri'])
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version = cpe_version(cpe['cpe23Uri'])
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# ignore when product is '-', which means N/A
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if product == '-':
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return
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op_start = ''
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op_end = ''
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v_start = ''
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v_end = ''
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if version != '*' and version != '-':
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# Version is defined, this is a '=' match
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op_start = '='
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v_start = version
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else:
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# Parse start version, end version and operators
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if 'versionStartIncluding' in cpe:
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op_start = '>='
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v_start = cpe['versionStartIncluding']
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if 'versionStartExcluding' in cpe:
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op_start = '>'
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v_start = cpe['versionStartExcluding']
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if 'versionEndIncluding' in cpe:
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op_end = '<='
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v_end = cpe['versionEndIncluding']
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if 'versionEndExcluding' in cpe:
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op_end = '<'
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v_end = cpe['versionEndExcluding']
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yield {
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'id': cpe['cpe23Uri'],
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'v_start': v_start,
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'op_start': op_start,
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'v_end': v_end,
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'op_end': op_end
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}
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def each_cpe(self):
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for node in self.nvd_cve['configurations']['nodes']:
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for cpe in self.parse_node(node):
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yield cpe
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@property
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def identifier(self):
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"""The CVE unique identifier"""
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return self.nvd_cve['cve']['CVE_data_meta']['ID']
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@property
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def affected_products(self):
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"""The set of CPE products referred by this CVE definition"""
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return set(cpe_product(p['id']) for p in self.each_cpe())
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def affects(self, name, version, cve_ignore_list, cpeid=None):
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"""
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True if the Buildroot Package object passed as argument is affected
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by this CVE.
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"""
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if self.identifier in cve_ignore_list:
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return self.CVE_DOESNT_AFFECT
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pkg_version = distutils.version.LooseVersion(version)
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if not hasattr(pkg_version, "version"):
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print("Cannot parse package '%s' version '%s'" % (name, version))
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pkg_version = None
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# if we don't have a cpeid, build one based on name and version
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if not cpeid:
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cpeid = "cpe:2.3:*:*:%s:%s:*:*:*:*:*:*:*" % (name, version)
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# if we have a cpeid, use its version instead of the package
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# version, as they might be different due to
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# <pkg>_CPE_ID_VERSION
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else:
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pkg_version = distutils.version.LooseVersion(cpe_version(cpeid))
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for cpe in self.each_cpe():
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if not cpe_matches(cpe['id'], cpeid):
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continue
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if not cpe['v_start'] and not cpe['v_end']:
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return self.CVE_AFFECTS
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if not pkg_version:
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continue
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if cpe['v_start']:
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try:
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cve_affected_version = distutils.version.LooseVersion(cpe['v_start'])
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inrange = ops.get(cpe['op_start'])(pkg_version, cve_affected_version)
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except TypeError:
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return self.CVE_UNKNOWN
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# current package version is before v_start, so we're
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# not affected by the CVE
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if not inrange:
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continue
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if cpe['v_end']:
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try:
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cve_affected_version = distutils.version.LooseVersion(cpe['v_end'])
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inrange = ops.get(cpe['op_end'])(pkg_version, cve_affected_version)
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except TypeError:
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return self.CVE_UNKNOWN
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# current package version is after v_end, so we're
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# not affected by the CVE
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if not inrange:
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continue
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# We're in the version range affected by this CVE
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return self.CVE_AFFECTS
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return self.CVE_DOESNT_AFFECT
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