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cert triage: Handle exceptions when searching for key usages #44

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cert triage: Handle exceptions when searching for key usages #44

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42 changes: 27 additions & 15 deletions dploot/triage/certificates.py
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
PublicFormat,
load_der_private_key,
)

from pyasn1.codec.der import decoder
from pyasn1.type.char import UTF8String

Expand Down Expand Up @@ -51,10 +52,15 @@ def dump(self) -> None:
print("Valid Date (UTC):\t%s" % self.cert.not_valid_before_utc)
print("Expiry Date (UTC):\t%s" % self.cert.not_valid_after_utc)
print("Extended Key Usage:")
for i in self.cert.extensions.get_extension_for_oid(
oid=ExtensionOID.EXTENDED_KEY_USAGE
).value:
print(f"\t{i._name} ({i.dotted_string})")
try:
for i in self.cert.extensions.get_extension_for_oid(
oid=ExtensionOID.EXTENDED_KEY_USAGE
).value:
print(f"\t{i._name} ({i.dotted_string})")
except x509.ExtensionNotFound:
pass
except (x509.DuplicateExtension, x509.UnsupportedGeneralNameType) as e:
logging.debug(e)

if self.clientauth:
print("\t[!] Certificate is used for client auth!")
Expand Down Expand Up @@ -368,17 +374,23 @@ def correlate_certificates_and_privatekeys(
"@", "_"
)
clientauth = False
for i in cert.extensions.get_extension_for_oid(
oid=ExtensionOID.EXTENDED_KEY_USAGE
).value:
if i.dotted_string in [
"1.3.6.1.5.5.7.3.2", # Client Authentication
"1.3.6.1.5.2.3.4", # PKINIT Client Authentication
"1.3.6.1.4.1.311.20.2.2", # Smart Card Logon
"2.5.29.37.0", # Any Purpose
]:
clientauth = True
break
try:
ext=cert.extensions.get_extension_for_oid(oid=ExtensionOID.EXTENDED_KEY_USAGE)
for i in ext.value:
if i.dotted_string in [
"1.3.6.1.5.5.7.3.2", # Client Authentication
"1.3.6.1.5.2.3.4", # PKINIT Client Authentication
"1.3.6.1.4.1.311.20.2.2", # Smart Card Logon
"2.5.29.37.0", # Any Purpose
]:
clientauth = True
break
except x509.ExtensionNotFound:
logging.debug('no extended key usage in certificate')
except (x509.DuplicateExtension, x509.UnsupportedGeneralNameType) as e:
logging.debug(e)


cert_object = Certificate(
winuser=winuser,
cert=cert,
Expand Down