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fix: modernize cvss score loading #4373

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merged 4 commits into from
Aug 29, 2024
Merged

fix: modernize cvss score loading #4373

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9917033
fix: modernize cvss score loading
terriko Aug 21, 2024
c5237b3
fix: add some basic input validation just in case
terriko Aug 27, 2024
a5a16a1
fix: add minimal cvss_vector character validation
terriko Aug 27, 2024
ee2d54c
fix: force score to be a float or uknonwn
terriko Aug 28, 2024
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93 changes: 73 additions & 20 deletions cve_bin_tool/data_sources/nvd_source.py
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Original file line number Diff line number Diff line change
Expand Up @@ -247,27 +247,80 @@ def format_data_api2(self, all_cve_entries):
continue

# Multiple ways of including CVSS metrics.
cve_cvss = cve_item
if "metrics" in cve_item:
# Newer data uses "impact" -- we may wish to delete the old below

# sometimes (frequently?) the impact is empty
if "impact" in cve_item:
if "baseMetricV3" in cve_item["impact"]:
cve["CVSS_version"] = 3
if "cvssV3" in cve_item["impact"]["baseMetricV3"]:
# grab either the data or some default values
cve["severity"] = cve_item["impact"]["baseMetricV3"][
"cvssV3"
].get("baseSeverity", "UNKNOWN")
cve["score"] = cve_item["impact"]["baseMetricV3"]["cvssV3"].get(
"baseScore", 0
)
cve["CVSS_vector"] = cve_item["impact"]["baseMetricV3"][
"cvssV3"
].get("vectorString", "")

# severity is in a different spot in v2 versus v3
elif "baseMetricV2" in cve_item["impact"]:
cve["CVSS_version"] = 2
cve["severity"] = cve_item["impact"]["baseMetricV4"].get(
"severity", "UNKNOWN"
)
if "cvssV2" in cve_item["impact"]["baseMetricV2"]:
cve["score"] = cve_item["impact"]["baseMetricV2"]["cvssV2"].get(
"baseScore", 0
)
cve["CVSS_vector"] = cve_item["impact"]["baseMetricV2"][
"cvssV2"
].get("vectorString", "")

# Old data used "metrics" -- This section may need to be deleted
elif "metrics" in cve_item:
cve_cvss = cve_item["metrics"]
# Get CVSSv3 or CVSSv2 score
cvss_available = True
if "cvssMetricV31" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV31"][0]["cvssData"]
cve["CVSS_version"] = 3
elif "cvssMetricV30" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV30"][0]["cvssData"]
cve["CVSS_version"] = 3
elif "cvssMetricV2" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV2"][0]["cvssData"]
cve["CVSS_version"] = 2
else:
LOGGER.debug(f"Unknown CVSS metrics field {cve_item['id']}")
cvss_available = False
if cvss_available:
cve["severity"] = cvss_data.get("baseSeverity", "UNKNOWN")
cve["score"] = cvss_data.get("baseScore", 0)
cve["CVSS_vector"] = cvss_data.get("vectorString", "")

# Get CVSSv3 or CVSSv2 score
cvss_available = True
if "cvssMetricV31" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV31"][0]["cvssData"]
cve["CVSS_version"] = 3
elif "cvssMetricV30" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV30"][0]["cvssData"]
cve["CVSS_version"] = 3
elif "cvssMetricV2" in cve_cvss:
cvss_data = cve_cvss["cvssMetricV2"][0]["cvssData"]
cve["CVSS_version"] = 2
else:
cvss_available = False
if cvss_available:
cve["severity"] = cvss_data.get("baseSeverity", "UNKNOWN")
cve["score"] = cvss_data.get("baseScore", 0)
cve["CVSS_vector"] = cvss_data.get("vectorString", "")
# End old metrics section

# do some basic input validation checks
# severity should be alphanumeric
if not cve["severity"].isalnum():
self.logger.debug(
f"Severity for {cve['id']} is invalid: {cve['severity']}"
)
cve["severity"] = re.sub(r"[\W]", "", cve["severity"])

# score should be numeric
try:
cve["score"] = float(cve["score"])
except ValueError:
self.logger.debug(f"Score for {cve['id']} is invalid: {cve['score']}")
cve["score"] = "invalid"

# CVSS_vector will be validated/normalized when cvss library is used but
# we can at least do a character filter here
# we expect letters (mostly but not always uppercase), numbers, : and /
cve["CVSS_vector"] = re.sub("[^A-Za-z0-9:/]", "", cve["CVSS_vector"])

cve_data.append(cve)

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