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Custom fake CBT flag for MSSQLClient via TDS.py #2098

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Custom fake CBT flag for MSSQLClient via TDS.py #2098

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efd0285
Add fake CBT value for NXC
Dec 23, 2025
f03cc54
Add fake CBT value for NXC
Dec 23, 2025
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13 changes: 11 additions & 2 deletions impacket/tds.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1220,6 +1220,7 @@ def kerberosLogin(
TGT=None,
TGS=None,
useCache=True,
cbt_fake_value=None
):
if hashes is not None:
lmhash, nthash = hashes.split(":")
Expand Down Expand Up @@ -1437,7 +1438,10 @@ def kerberosLogin(
chkField["Lgth"] = 16
chkField["Flags"] = GSS_C_SEQUENCE_FLAG | GSS_C_REPLAY_FLAG
if self.tlsSocket:
chkField["Bnd"] = self.generate_cbt_from_tls_unique()
if cbt_fake_value is not None:
chkField["Bnd"] = cbt_fake_value
else:
chkField["Bnd"] = self.generate_cbt_from_tls_unique()
authenticator["cksum"]["checksum"] = chkField.getData()
authenticator["seq-number"] = 0
encodedAuthenticator = encoder.encode(authenticator)
Expand Down Expand Up @@ -1488,6 +1492,7 @@ def login(
domain="",
hashes=None,
useWindowsAuth=False,
cbt_fake_value=None
):

if hashes is not None:
Expand Down Expand Up @@ -1573,7 +1578,10 @@ def login(
# We then compute the Channel Binding Token from the tls-unique value retrieved before
channel_binding_value = b""
if self.tlsSocket:
channel_binding_value = self.generate_cbt_from_tls_unique()
if cbt_fake_value is not None:
channel_binding_value = cbt_fake_value
else:
channel_binding_value = self.generate_cbt_from_tls_unique()

# Generate the NTLM ChallengeResponse AUTH
type3, exportedSessionKey = ntlm.getNTLMSSPType3(
Expand Down Expand Up @@ -2306,3 +2314,4 @@ def workstation_id(self):
@property
def application_name(self):
return self._application_name