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Diffstat (limited to 'scripts/cvert.py')
| -rw-r--r-- | scripts/cvert.py | 473 |
1 files changed, 473 insertions, 0 deletions
diff --git a/scripts/cvert.py b/scripts/cvert.py new file mode 100644 index 0000000000..f93b95c849 --- /dev/null +++ b/scripts/cvert.py @@ -0,0 +1,473 @@ +#!/usr/bin/env python3 +# +# Copyright (c) 2018 by Cisco Systems, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License version 2 as +# published by the Free Software Foundation. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program; if not, write to the Free Software Foundation, Inc., +# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +# + +""" CVERT library: set of functions for CVE reports +""" + + +import os +import re +import sys +import json +import gzip +import pickle +import logging +import hashlib +import datetime +import textwrap +import urllib.request +import distutils.version + + +logging.getLogger(__name__).addHandler(logging.NullHandler()) + + +def generate_report(manifest, cve_struct): + """Generate CVE report""" + + report = [] + + for cve in cve_struct: + affected = set() + + for conf in cve_struct[cve]["nodes"]: + affected = affected.union(process_configuration(manifest, conf)) + + for key in affected: + product, version = key.split(",") + patched = manifest[product][version] + + if cve in patched: + cve_item = {"status": "patched"} + else: + cve_item = {"status": "unpatched"} + + cve_item["CVSS"] = "{0:.1f}".format(cve_struct[cve]["score"]) + cve_item["CVE"] = cve + cve_item["product"] = product + cve_item["version"] = version + cve_item["description"] = cve_struct[cve]["description"] + cve_item["reference"] = [x["url"] for x in cve_struct[cve]["reference"]] + + logging.debug("%9s %s %s,%s", + cve_item["status"], cve_item["CVE"], + cve_item["product"], cve_item["version"]) + + report.append(cve_item) + + return sorted(report, key=lambda x: (x["status"], x["product"], x["CVSS"], x["CVE"])) + + +def process_configuration(manifest, conf): + """Recursive call to process all CVE configurations""" + + operator = conf["operator"] + + if operator not in ["OR", "AND"]: + raise ValueError("operator {} is not supported".format(operator)) + + operator = True if operator == "AND" else False + match = False + affected = set() + + if "cpe" in conf: + match = process_cpe(manifest, conf["cpe"][0], affected) + + for cpe in conf["cpe"][1:]: + package_match = process_cpe(manifest, cpe, affected) + + # match = match <operator> package_match + match = operator ^ ((operator ^ match) or (operator ^ package_match)) + elif "children" in conf: + product_set = process_configuration(manifest, conf["children"][0]) + + if product_set: + match = True + affected = affected.union(product_set) + + for child in conf["children"][1:]: + product_set = process_configuration(manifest, child) + package_match = True if product_set else False + + # match = match OP package_match + match = operator ^ ((operator ^ match) or (operator ^ package_match)) + + if package_match: + affected = affected.union(product_set) + + if match: + return affected + + return () + + +def process_cpe(manifest, cpe, affected): + """Match CPE with all manifest packages""" + + if not cpe["vulnerable"]: + # ignore non vulnerable part + return False + + version_range = {} + + for flag in ["versionStartIncluding", + "versionStartExcluding", + "versionEndIncluding", + "versionEndExcluding"]: + if flag in cpe: + version_range[flag] = cpe[flag] + + # take only "product" and "version" + product, version = cpe["cpe23Uri"].split(":")[4:6] + + if product not in manifest: + return False + + if not version_range: + if version == "*": + # ignore CVEs that touches all versions of package, + # can not fix it anyway + logging.debug('ignore "*" in %s', cpe["cpe23Uri"]) + return False + elif version == "-": + # "-" means NA + # + # NA (i.e. "not applicable/not used"). The logical value NA + # SHOULD be assigned when there is no legal or meaningful + # value for that attribute, or when that attribute is not + # used as part of the description. + # This includes the situation in which an attribute has + # an obtainable value that is null + # + # Ignores CVEs if version is not set + logging.debug('ignore "-" in %s', cpe["cpe23Uri"]) + return False + else: + version_range["versionExactMatch"] = version + + result = False + + for version in manifest[product]: + try: + if match_version(version, + version_range): + logging.debug("match %s %s: %s", product, version, cpe["cpe23Uri"]) + affected.add("{},{}".format(product, version)) + + result = True + except TypeError: + # version comparison is a very tricky + # sometimes provider changes product version in a strange manner + # and the above comparison just failed + # so here we try to make version string "more standard" + + if match_version(twik_version(version), + [twik_version(v) for v in version_range]): + logging.debug("match %s %s (twiked): %s", product, twik_version(version), + cpe["cpe23Uri"]) + affected.add("{},{}".format(product, version)) + + result = True + + return result + + +def match_version(version, vrange): + """Match version with the version range""" + + result = False + version = util_version(version) + + if "versionExactMatch" in vrange: + if version == util_version(vrange["versionExactMatch"]): + result = True + else: + result = True + + if "versionStartIncluding" in vrange: + result = result and version >= util_version(vrange["versionStartIncluding"]) + + if "versionStartExcluding" in vrange: + result = result and version > util_version(vrange["versionStartExcluding"]) + + if "versionEndIncluding" in vrange: + result = result and version <= util_version(vrange["versionEndIncluding"]) + + if "versionEndExcluding" in vrange: + result = result and version < util_version(vrange["versionEndExcluding"]) + + return result + + +def util_version(version): + """Simplify package version""" + return distutils.version.LooseVersion(version.split("+git")[0]) + + +def twik_version(version): + """Return "standard" version for complex cases""" + return "v1" + re.sub(r"^[a-zA-Z]+", "", version) + + +def print_report(report, width=70, show_description=False, show_reference=False, output=sys.stdout): + """Print out final report""" + + for cve in report: + print("{0:>9s} | {1:>4s} | {2:18s} | {3} | {4}".format(cve["status"], cve["CVSS"], + cve["CVE"], cve["product"], + cve["version"]), + file=output) + + if show_description: + print("{0:>9s} + {1}".format(" ", "Description"), file=output) + + for lin in textwrap.wrap(cve["description"], width=width): + print("{0:>9s} {1}".format(" ", lin), file=output) + + if show_reference: + print("{0:>9s} + {1}".format(" ", "Reference"), file=output) + + for url in cve["reference"]: + print("{0:>9s} {1}".format(" ", url), file=output) + + +def update_feeds(feed_dir, offline=False, start=2002): + """Update all JSON feeds""" + + feed_dir = os.path.realpath(feed_dir) + year_now = datetime.datetime.now().year + cve_struct = {} + + for year in range(start, year_now + 1): + update_year(cve_struct, year, feed_dir, offline) + + return cve_struct + + +def update_year(cve_struct, year, feed_dir, offline): + """Update one JSON feed for the particular year""" + + url_prefix = "https://static.nvd.nist.gov/feeds/json/cve/1.0" + file_prefix = "nvdcve-1.0-{0}".format(year) + + meta = { + "url": "{0}/{1}.meta".format(url_prefix, file_prefix), + "file": os.path.join(feed_dir, "{0}.meta".format(file_prefix)) + } + + feed = { + "url": "{0}/{1}.json.gz".format(url_prefix, file_prefix), + "file": os.path.join(feed_dir, "{0}.json.gz".format(file_prefix)) + } + + ctx = {} + + if not offline: + ctx = download_feed(meta, feed) + + if not "meta" in ctx or not "feed" in ctx: + return + + if not os.path.isfile(meta["file"]): + return + + if not os.path.isfile(feed["file"]): + return + + if not "meta" in ctx: + ctx["meta"] = ctx_meta(meta["file"]) + + if not "sha256" in ctx["meta"]: + return + + if not "feed" in ctx: + ctx["feed"] = ctx_gzip(feed["file"], ctx["meta"]["sha256"]) + + if not ctx["feed"]: + return + + logging.debug("parsing year %s", year) + + for cve_item in ctx["feed"]["CVE_Items"]: + iden, cve = parse_item(cve_item) + + if not iden: + continue + + if not cve: + logging.error("%s parse error", iden) + break + + if iden in cve_struct: + logging.error("%s duplicated", iden) + break + + cve_struct[iden] = cve + + logging.debug("cve records: %d", len(cve_struct)) + + +def ctx_meta(filename): + """Parse feed meta file""" + + if not os.path.isfile(filename): + return {} + + ctx = {} + + with open(filename) as fil: + for lin in fil: + pair = lin.split(":", maxsplit=1) + ctx[pair[0]] = pair[1].rstrip() + + return ctx + + +def ctx_gzip(filename, checksum=""): + """Parse feed archive file""" + + if not os.path.isfile(filename): + return {} + + with gzip.open(filename) as fil: + try: + ctx = fil.read() + except (EOFError, OSError): + logging.error("failed to process gz archive %s", filename, exc_info=True) + return {} + + if checksum and checksum.upper() != hashlib.sha256(ctx).hexdigest().upper(): + return {} + + return json.loads(ctx.decode()) + + +def parse_item(cve_item): + """Parse one JSON CVE entry""" + + cve_id = cve_item["cve"]["CVE_data_meta"]["ID"][:] + impact = cve_item["impact"] + + if not impact: + # REJECTed CVE + return None, None + + if "baseMetricV3" in impact: + score = impact["baseMetricV3"]["cvssV3"]["baseScore"] + elif "baseMetricV2" in impact: + score = impact["baseMetricV2"]["cvssV2"]["baseScore"] + else: + return cve_id, None + + return cve_id, { + "score": score, + "nodes": cve_item["configurations"]["nodes"][:], + "reference": cve_item["cve"]["references"]["reference_data"][:], + "description": cve_item["cve"]["description"]["description_data"][0]["value"] + } + + +def download_feed(meta, feed): + """Download and parse feed""" + + ctx = {} + + if not retrieve_url(meta["url"], meta["file"]): + return {} + + ctx["meta"] = ctx_meta(meta["file"]) + + if not "sha256" in ctx["meta"]: + return {} + + ctx["feed"] = ctx_gzip(feed["file"], ctx["meta"]["sha256"]) + + if not ctx["feed"]: + if not retrieve_url(feed["url"], feed["file"]): + return {} + + ctx["feed"] = ctx_gzip(feed["file"], ctx["meta"]["sha256"]) + + return ctx + + +def retrieve_url(url, filename=None): + """Download file by URL""" + + if filename: + os.makedirs(os.path.dirname(filename), exist_ok=True) + + logging.debug("downloading %s", url) + + try: + urllib.request.urlretrieve(url, filename=filename) + except urllib.error.HTTPError: + logging.error("failed to download URL %s", url, exc_info=True) + return False + + return True + + +def logconfig(debug_flag=False): + """Return default log config""" + + return { + "version": 1, + "formatters": { + "f": { + "format": "# %(asctime)s %% CVERT %% %(levelname)-8s %% %(message)s" + } + }, + "handlers": { + "h": { + "class": "logging.StreamHandler", + "formatter": "f", + "level": logging.DEBUG if debug_flag else logging.INFO + } + }, + "root": { + "handlers": ["h"], + "level": logging.DEBUG if debug_flag else logging.INFO + }, + } + + +def save_cve(filename, cve_struct): + """Save CVE structure in the file""" + + filename = os.path.realpath(filename) + + logging.debug("saving %d CVE records to %s", len(cve_struct), filename) + + with open(filename, "wb") as fil: + pickle.dump(cve_struct, fil) + + +def load_cve(filename): + """Load CVE structure from the file""" + + filename = os.path.realpath(filename) + + logging.debug("loading from %s", filename) + + with open(filename, "rb") as fil: + cve_struct = pickle.load(fil) + + logging.debug("cve records: %d", len(cve_struct)) + + return cve_struct |