Merge pull request from GHSA-f4g9-h89h-jgv9

Validate XML documents before verifying the signature

7 files changed, 297 insertions, 13 deletions

diff --git a/tests/saml2_response_xsw.xml b/tests/saml2_response_xsw.xml
deleted file mode 100644
index 3671eb48..00000000
--- a/tests/saml2_response_xsw.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<ns0:Response xmlns:ns0="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:ns1="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ns2="http://www.w3.org/2000/09/xmldsig#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" Destination="http://lingon.catalogix.se:8087/" ID="id-vqOQ72JCppXaBWnBE" InResponseTo="id12" IssueInstant="2019-12-20T12:15:16Z" Version="2.0"><ns1:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">urn:mace:example.com:saml:roland:idp</ns1:Issuer><ns0:Status><ns0:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/></ns0:Status><ns1:Assertion ID="id-SPOOFED_ASSERTION" IssueInstant="2019-12-20T12:15:16Z" Version="2.0"><ns1:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">urn:mace:example.com:saml:roland:idp</ns1:Issuer><ns2:Signature Id="Signature2"><ns2:SignedInfo><ns2:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ns2:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/><ns2:Reference URI="#id-Aa9IWfDxJVIX6GQye"><ns2:Transforms><ns2:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><ns2:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ns2:Transforms><ns2:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ns2:DigestValue>EWBvQUlrwQbtrAjuUXkSBAVsZ50=</ns2:DigestValue></ns2:Reference></ns2:SignedInfo><ns2:SignatureValue>m4zRgTWleMcx1dFboeiYlbiDigHWAVhHVa+GLN++ELNMFDutuzBxc3tu6okyaNQGW3leu32wzbfdpb5+3RlpGoKj2wPX570/EMJj4uw91XfXsZfpNP+5GlgNT8w/elDmBXhG/KwmSO477Imk0szKovTBMVHmo3QOd+ba//dVsJE=</ns2:SignatureValue><ns2:KeyInfo><ns2:X509Data><ns2:X509Certificate>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</ns2:X509Certificate></ns2:X509Data></ns2:KeyInfo></ns2:Signature><ns1:Subject><ns1:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:transient" NameQualifier="" SPNameQualifier="id12">ANOTHER_ID</ns1:NameID><ns1:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><ns1:SubjectConfirmationData InResponseTo="id12" NotOnOrAfter="2019-12-20T12:20:16Z" Recipient="http://lingon.catalogix.se:8087/"/></ns1:SubjectConfirmation></ns1:Subject><ns1:Conditions NotBefore="2019-12-20T12:15:16Z" NotOnOrAfter="2019-12-20T12:20:16Z"><ns1:AudienceRestriction><ns1:Audience>urn:mace:example.com:saml:roland:sp</ns1:Audience></ns1:AudienceRestriction></ns1:Conditions><ns1:AuthnStatement AuthnInstant="2019-12-20T12:15:16Z" SessionIndex="id-eEhNCc5BSiesVOl8B"><ns1:AuthnContext><ns1:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocolPassword</ns1:AuthnContextClassRef><ns1:AuthenticatingAuthority>http://www.example.com/login</ns1:AuthenticatingAuthority></ns1:AuthnContext></ns1:AuthnStatement><ns1:AttributeStatement><ns1:Attribute FriendlyName="eduPersonAffiliation" Name="urn:oid:1.3.6.1.4.1.5923.1.1.1.1" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">staff</ns1:AttributeValue><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">ADMIN</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="mail" Name="urn:oid:0.9.2342.19200300.100.1.3" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">HACKER@gmail.com</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="givenName" Name="urn:oid:2.5.4.42" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">Derek</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="surName" Name="urn:oid:2.5.4.4" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">Jeter</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="title" Name="urn:oid:2.5.4.12" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">shortstop</ns1:AttributeValue></ns1:Attribute></ns1:AttributeStatement></ns1:Assertion>
-<XSW_ATTACK>
-<ns1:Assertion ID="id-Aa9IWfDxJVIX6GQye" IssueInstant="2019-12-20T12:15:16Z" Version="2.0"><ns1:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">urn:mace:example.com:saml:roland:idp</ns1:Issuer><ns1:Subject><ns1:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:transient" NameQualifier="" SPNameQualifier="id12">ac5b22bb8eac4a26ed07a55432a0fe0da243f6e911aa614cff402c44d7cdec36</ns1:NameID><ns1:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><ns1:SubjectConfirmationData InResponseTo="id12" NotOnOrAfter="2019-12-20T12:20:16Z" Recipient="http://lingon.catalogix.se:8087/"/></ns1:SubjectConfirmation></ns1:Subject><ns1:Conditions NotBefore="2019-12-20T12:15:16Z" NotOnOrAfter="2019-12-20T12:20:16Z"><ns1:AudienceRestriction><ns1:Audience>urn:mace:example.com:saml:roland:sp</ns1:Audience></ns1:AudienceRestriction></ns1:Conditions><ns1:AuthnStatement AuthnInstant="2019-12-20T12:15:16Z" SessionIndex="id-eEhNCc5BSiesVOl8B"><ns1:AuthnContext><ns1:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocolPassword</ns1:AuthnContextClassRef><ns1:AuthenticatingAuthority>http://www.example.com/login</ns1:AuthenticatingAuthority></ns1:AuthnContext></ns1:AuthnStatement><ns1:AttributeStatement><ns1:Attribute FriendlyName="eduPersonAffiliation" Name="urn:oid:1.3.6.1.4.1.5923.1.1.1.1" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">staff</ns1:AttributeValue><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">member</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="mail" Name="urn:oid:0.9.2342.19200300.100.1.3" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">foo@gmail.com</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="givenName" Name="urn:oid:2.5.4.42" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">Derek</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="surName" Name="urn:oid:2.5.4.4" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">Jeter</ns1:AttributeValue></ns1:Attribute><ns1:Attribute FriendlyName="title" Name="urn:oid:2.5.4.12" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"><ns1:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string">shortstop</ns1:AttributeValue></ns1:Attribute></ns1:AttributeStatement></ns1:Assertion>
-</XSW_ATTACK>
-</ns0:Response>
diff --git a/tests/test_xsw.py b/tests/test_xsw.py
index 9978c4d3..0e92a5bd 100644
--- a/tests/test_xsw.py
+++ b/tests/test_xsw.py
@@ -14,27 +14,101 @@ from pathutils import dotname
 from pathutils import full_path
 
 
-XML_RESPONSE_XSW = full_path("saml2_response_xsw.xml")
+SIGNED_XSW_ASSERTION_WRAPPER = full_path("xsw/signed-xsw-assertion-wrapper.xml")
+SIGNED_XSW_ASSERTION_EXTENSIONS = full_path("xsw/signed-xsw-assertion-extensions.xml")
+SIGNED_XSW_ASSERTION_ASSERTION = full_path("xsw/signed-xsw-assertion-assertion.xml")
 
+SIGNED_ASSERTION_FIRST_SIG = full_path("xsw/signed-xsw-assertion-in-assertion-first-sig.xml")
+SIGNED_REPONSE_FIRST_SIG = full_path("xsw/signed-xsw-response-in-response-first-sig.xml")
 
-class TestAuthnResponse:
+
+class TestXSW:
+    def setup_class(self):
+        self.conf = config_factory("sp", dotname("server_conf"))
+        self.ar = authn_response(self.conf, return_addrs="https://example.org/acs/post")
+
+    @patch('saml2.response.validate_on_or_after', return_value=True)
+    def test_signed_xsw_assertion_wrapper_should_fail(self, mock_validate_on_or_after):
+        self.ar.issue_instant_ok = Mock(return_value=True)
+
+        with open(SIGNED_XSW_ASSERTION_WRAPPER) as fp:
+            xml_response = fp.read()
+
+        self.ar.outstanding_queries = {"id-abc": "http://localhost:8088/sso"}
+        self.ar.timeslack = 10000
+        self.ar.loads(xml_response, decode=False)
+
+        assert self.ar.came_from == 'http://localhost:8088/sso'
+        assert self.ar.session_id() == "id-abc"
+        assert self.ar.issuer() == 'urn:mace:example.com:saml:roland:idp'
+
+        with raises(SignatureError):
+            self.ar.verify()
+
+        assert self.ar.ava is None
+        assert self.ar.name_id is None
+
+    @patch('saml2.response.validate_on_or_after', return_value=True)
+    def test_signed_xsw_assertion_extensions_should_fail(self, mock_validate_on_or_after):
+        self.ar.issue_instant_ok = Mock(return_value=True)
+
+        with open(SIGNED_XSW_ASSERTION_EXTENSIONS) as fp:
+            xml_response = fp.read()
+
+        self.ar.outstanding_queries = {"id-abc": "http://localhost:8088/sso"}
+        self.ar.timeslack = 10000
+        self.ar.loads(xml_response, decode=False)
+
+        assert self.ar.came_from == 'http://localhost:8088/sso'
+        assert self.ar.session_id() == "id-abc"
+        assert self.ar.issuer() == 'urn:mace:example.com:saml:roland:idp'
+
+        with raises(SignatureError):
+            self.ar.verify()
+
+        assert self.ar.ava is None
+        assert self.ar.name_id is None
+
+    @patch('saml2.response.validate_on_or_after', return_value=True)
+    def test_signed_xsw_assertion_assertion_should_fail(self, mock_validate_on_or_after):
+        self.ar.issue_instant_ok = Mock(return_value=True)
+
+        with open(SIGNED_XSW_ASSERTION_ASSERTION) as fp:
+            xml_response = fp.read()
+
+        self.ar.outstanding_queries = {"id-abc": "http://localhost:8088/sso"}
+        self.ar.timeslack = 10000
+        self.ar.loads(xml_response, decode=False)
+
+        assert self.ar.came_from == 'http://localhost:8088/sso'
+        assert self.ar.session_id() == "id-abc"
+        assert self.ar.issuer() == 'urn:mace:example.com:saml:roland:idp'
+
+        with raises(SignatureError):
+            self.ar.verify()
+
+        assert self.ar.ava is None
+        assert self.ar.name_id is None
+
+
+class TestInvalidDepthFirstSig:
     def setup_class(self):
         self.conf = config_factory("sp", dotname("server_conf"))
-        self.ar = authn_response(self.conf, "http://lingon.catalogix.se:8087/")
+        self.ar = authn_response(self.conf, return_addrs="https://example.org/acs/post")
 
     @patch('saml2.response.validate_on_or_after', return_value=True)
-    def test_verify_signed_xsw(self, mock_validate_on_or_after):
+    def test_signed_assertion_first_sig_should_fail(self, mock_validate_on_or_after):
         self.ar.issue_instant_ok = Mock(return_value=True)
 
-        with open(XML_RESPONSE_XSW) as fp:
+        with open(SIGNED_ASSERTION_FIRST_SIG) as fp:
             xml_response = fp.read()
 
-        self.ar.outstanding_queries = {"id12": "http://localhost:8088/sso"}
+        self.ar.outstanding_queries = {"id-abc": "http://localhost:8088/sso"}
         self.ar.timeslack = 10000
         self.ar.loads(xml_response, decode=False)
 
         assert self.ar.came_from == 'http://localhost:8088/sso'
-        assert self.ar.session_id() == "id12"
+        assert self.ar.session_id() == "id-abc"
         assert self.ar.issuer() == 'urn:mace:example.com:saml:roland:idp'
 
         with raises(SignatureError):
@@ -42,3 +116,15 @@ class TestAuthnResponse:
 
         assert self.ar.ava is None
         assert self.ar.name_id is None
+
+    @patch('saml2.response.validate_on_or_after', return_value=True)
+    def test_signed_response_first_sig_should_fail(self, mock_validate_on_or_after):
+        self.ar.issue_instant_ok = Mock(return_value=True)
+
+        with open(SIGNED_REPONSE_FIRST_SIG) as fp:
+            xml_response = fp.read()
+
+        self.ar.outstanding_queries = {"id-abc": "http://localhost:8088/sso"}
+        self.ar.timeslack = 10000
+        with raises(SignatureError):
+            self.ar.loads(xml_response, decode=False)
diff --git a/tests/xsw/signed-xsw-assertion-assertion.xml b/tests/xsw/signed-xsw-assertion-assertion.xml
new file mode 100644
index 00000000..3d1ea19e
--- /dev/null
+++ b/tests/xsw/signed-xsw-assertion-assertion.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-response" IssueInstant="2020-12-04T07:48:09.700Z" InResponseTo="id-abc" Destination="https://example.org/acs/post">
+    <saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+    <samlp:Status>
+        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+    </samlp:Status>
+    <saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-attack-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/><ds:Reference URI="#the-assertion"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>dOks15WkdjeZbZZE1IuDjmTCmgY=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>CCGBBssMsEikFV7mkPw1+/W5O8Q6y2I96LWTOFpa51GpaHbZ48jRVZf1vEp5hmfMa4p3/aFH8kXZuIyqvtlxs7U6j/NI4k9t9aF3TY0VNGJjlh2aC08pzNicV1J8MKtQi4PNmxCdbhVmvrWNcx2JhG4dPqfj5oyv0LpxK2zi2JI=</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>MIICsDCCAhmgAwIBAgIJAJrzqSSwmDY9MA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNVBAYTAkFVMRMwEQYDVQQIEwpTb21lLVN0YXRlMSEwHwYDVQQKExhJbnRlcm5ldCBXaWRnaXRzIFB0eSBMdGQwHhcNMDkxMDA2MTk0OTQxWhcNMDkxMTA1MTk0OTQxWjBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEhMB8GA1UEChMYSW50ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDJg2cms7MqjniT8Fi/XkNHZNPbNVQyMUMXE9tXOdqwYCA1cc8vQdzkihscQMXy3iPw2cMggBu6gjMTOSOxECkuvX5ZCclKr8pXAJM5cY6gVOaVO2PdTZcvDBKGbiaNefiEw5hnoZomqZGp8wHNLAUkwtH9vjqqvxyS/vclc6k2ewIDAQABo4GnMIGkMB0GA1UdDgQWBBRePsKHKYJsiojE78ZWXccK9K4aJTB1BgNVHSMEbjBsgBRePsKHKYJsiojE78ZWXccK9K4aJaFJpEcwRTELMAkGA1UEBhMCQVUxEzARBgNVBAgTClNvbWUtU3RhdGUxITAfBgNVBAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZIIJAJrzqSSwmDY9MAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEFBQADgYEAJSrKOEzHO7TL5cy6h3qh+3+JAk8HbGBW+cbX6KBCAw/mzU8flK25vnWwXS3dv2FF3Aod0/S7AWNfKib5U/SA9nJaz/mWeF9S0farz9AQFc8/NSzAzaVq7YbM4F6f6N2FRl7GikdXRCed45j6mrPzGzk3ECbupFnqyREH3+ZPSdk=</ds:X509Certificate></ds:X509Data></ds:KeyInfo></ds:Signature><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">attack-name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement><saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion></saml:Assertion>
+</samlp:Response>
diff --git a/tests/xsw/signed-xsw-assertion-extensions.xml b/tests/xsw/signed-xsw-assertion-extensions.xml
new file mode 100644
index 00000000..1bd2a8b6
--- /dev/null
+++ b/tests/xsw/signed-xsw-assertion-extensions.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-response" IssueInstant="2020-12-04T07:48:09.700Z" InResponseTo="id-abc" Destination="https://example.org/acs/post">
+    <saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+    <samlp:Extensions><saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion></samlp:Extensions>
+    <samlp:Status>
+        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+    </samlp:Status>
+    <saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-attack-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/><ds:Reference URI="#the-assertion"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>dOks15WkdjeZbZZE1IuDjmTCmgY=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>CCGBBssMsEikFV7mkPw1+/W5O8Q6y2I96LWTOFpa51GpaHbZ48jRVZf1vEp5hmfMa4p3/aFH8kXZuIyqvtlxs7U6j/NI4k9t9aF3TY0VNGJjlh2aC08pzNicV1J8MKtQi4PNmxCdbhVmvrWNcx2JhG4dPqfj5oyv0LpxK2zi2JI=</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></ds:KeyInfo></ds:Signature><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion>
+</samlp:Response>
diff --git a/tests/xsw/signed-xsw-assertion-in-assertion-first-sig.xml b/tests/xsw/signed-xsw-assertion-in-assertion-first-sig.xml
new file mode 100644
index 00000000..53ab46ea
--- /dev/null
+++ b/tests/xsw/signed-xsw-assertion-in-assertion-first-sig.xml
@@ -0,0 +1,85 @@
+<?xml version="1.0"?>
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" ID="the-response-id" InResponseTo="id-abc" Version="2.0" IssueInstant="2020-09-14T22:37:32Z" Destination="https://example.org/acs/post">
+	<saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">urn:mace:example.com:saml:roland:idp</saml:Issuer>
+	<samlp:Status xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
+		<samlp:StatusCode xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+	</samlp:Status>
+	<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ID="attack-assertion-id" IssueInstant="2020-09-14T22:37:32Z" Version="2.0">
+	<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ID="the-assertion-id" IssueInstant="2020-09-14T22:37:32Z" Version="2.0">
+		<saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+		<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+			<ds:SignedInfo>
+				<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+				<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
+				<ds:Reference URI="#the-assertion-id">
+					<ds:Transforms>
+						<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
+						<ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+					</ds:Transforms>
+					<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
+					<ds:DigestValue>iLDF5/5VJs4sb3TasVTvFCsIi0k=</ds:DigestValue>
+				</ds:Reference>
+			</ds:SignedInfo>
+			<ds:SignatureValue>Ked5gvNcRhHCivVN9y9+5LDAZLqLhRg3Sw2xlRR4HP2am1mFoBDdUx4khEWdcC2dknbzfo2AC1AtcbHTogDLOSLzYX9sT/gj995qotu4fUFQPMiocbCZRpbXTI6iDRiytwYtAkw28yQ4FVCe99GUThbV9tpLIoqMPZYNJ3TmL/I=</ds:SignatureValue>
+			<ds:KeyInfo>
+				<ds:X509Data>
+					<ds:X509Certificate>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</ds:X509Certificate>
+				</ds:X509Data>
+			</ds:KeyInfo>
+		</ds:Signature>
+		<saml:Subject>
+			<saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">the-name-id</saml:NameID>
+			<saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
+				<saml:SubjectConfirmationData InResponseTo="id-abc" NotOnOrAfter="2020-09-14T22:47:32Z" Recipient="https://example.org/acs/post"/>
+			</saml:SubjectConfirmation>
+		</saml:Subject>
+		<saml:Conditions NotBefore="2020-09-14T22:27:32Z" NotOnOrAfter="2020-09-14T22:47:32Z">
+			<saml:AudienceRestriction>
+				<saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience>
+			</saml:AudienceRestriction>
+		</saml:Conditions>
+		<saml:AuthnStatement AuthnInstant="2020-09-14T22:37:32Z" SessionIndex="id-sessidx">
+			<saml:AuthnContext>
+				<saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml:AuthnContextClassRef>
+			</saml:AuthnContext>
+		</saml:AuthnStatement>
+	</saml:Assertion>
+		<saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+		<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+			<ds:SignedInfo>
+				<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+				<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
+				<ds:Reference URI="#attack-assertion-id">
+					<ds:Transforms>
+						<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
+						<ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+					</ds:Transforms>
+					<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
+					<ds:DigestValue>dGhpcyBpcyBza2lwcGVkOyBvbmx5IHRoZSBmaXJzdCBzaWduYXR1cmUgaXMgcHJvY2Vzc2VkCg==</ds:DigestValue>
+				</ds:Reference>
+			</ds:SignedInfo>
+			<ds:SignatureValue>dGhpcyBpcyBza2lwcGVkOyBvbmx5IHRoZSBmaXJzdCBzaWduYXR1cmUgaXMgcHJvY2Vzc2VkCg==</ds:SignatureValue>
+			<ds:KeyInfo>
+				<ds:X509Data>
+					<ds:X509Certificate>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</ds:X509Certificate>
+				</ds:X509Data>
+			</ds:KeyInfo>
+		</ds:Signature>
+		<saml:Subject>
+			<saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">attack-name-id</saml:NameID>
+			<saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
+				<saml:SubjectConfirmationData InResponseTo="id-abc" NotOnOrAfter="2020-09-14T22:47:32Z" Recipient="https://example.org/acs/post"/>
+			</saml:SubjectConfirmation>
+		</saml:Subject>
+		<saml:Conditions NotBefore="2020-09-14T22:27:32Z" NotOnOrAfter="2020-09-14T22:47:32Z">
+			<saml:AudienceRestriction>
+				<saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience>
+			</saml:AudienceRestriction>
+		</saml:Conditions>
+		<saml:AuthnStatement AuthnInstant="2020-09-14T22:37:32Z" SessionIndex="id-sessidx">
+			<saml:AuthnContext>
+				<saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml:AuthnContextClassRef>
+			</saml:AuthnContext>
+		</saml:AuthnStatement>
+	</saml:Assertion>
+</samlp:Response>
diff --git a/tests/xsw/signed-xsw-assertion-wrapper.xml b/tests/xsw/signed-xsw-assertion-wrapper.xml
new file mode 100644
index 00000000..37d1fa5d
--- /dev/null
+++ b/tests/xsw/signed-xsw-assertion-wrapper.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-response" IssueInstant="2020-12-04T07:48:09.700Z" InResponseTo="id-abc" Destination="https://example.org/acs/post">
+    <saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+    <samlp:Status>
+        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+    </samlp:Status>
+    <saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-attack-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/><ds:Reference URI="#the-assertion"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>dOks15WkdjeZbZZE1IuDjmTCmgY=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>CCGBBssMsEikFV7mkPw1+/W5O8Q6y2I96LWTOFpa51GpaHbZ48jRVZf1vEp5hmfMa4p3/aFH8kXZuIyqvtlxs7U6j/NI4k9t9aF3TY0VNGJjlh2aC08pzNicV1J8MKtQi4PNmxCdbhVmvrWNcx2JhG4dPqfj5oyv0LpxK2zi2JI=</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></ds:KeyInfo></ds:Signature><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">attack-name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion>
+    <XSW_ATTACK>
+        <saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Version="2.0" ID="the-assertion" IssueInstant="2020-12-04T07:48:09.600Z"><saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer><saml:Subject><saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">name-id</saml:NameID><saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer"><saml:SubjectConfirmationData NotOnOrAfter="2020-12-04T07:58:09.600Z" Recipient="https://example.org/acs/post" InResponseTo="id-abc"/></saml:SubjectConfirmation></saml:Subject><saml:Conditions NotBefore="2020-12-04T07:48:09.600Z" NotOnOrAfter="2020-12-04T07:58:09.600Z"><saml:AudienceRestriction><saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement AuthnInstant="2020-12-04T07:48:09.600Z" SessionNotOnOrAfter="2020-12-04T07:58:09.600Z" SessionIndex="id-sessidx"><saml:AuthnContext><saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion>
+    </XSW_ATTACK>
+</samlp:Response>
diff --git a/tests/xsw/signed-xsw-response-in-response-first-sig.xml b/tests/xsw/signed-xsw-response-in-response-first-sig.xml
new file mode 100644
index 00000000..a400b2ae
--- /dev/null
+++ b/tests/xsw/signed-xsw-response-in-response-first-sig.xml
@@ -0,0 +1,91 @@
+<?xml version="1.0"?>
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" ID="attack-response-id" InResponseTo="id-abc" Version="2.0" IssueInstant="2020-09-14T22:37:32Z" Destination="https://example.org/acs/post">
+<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" ID="the-response-id" InResponseTo="id-abc" Version="2.0" IssueInstant="2020-09-14T22:37:32Z" Destination="https://example.org/acs/post">
+	<saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">urn:mace:example.com:saml:roland:idp</saml:Issuer>
+	<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+		<ds:SignedInfo>
+			<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+			<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
+			<ds:Reference URI="#the-response-id">
+				<ds:Transforms>
+					<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
+					<ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+				</ds:Transforms>
+				<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
+				<ds:DigestValue>ykldcjeUTA6xMqk+BUQy9hvraOo=</ds:DigestValue>
+			</ds:Reference>
+		</ds:SignedInfo>
+		<ds:SignatureValue>TF6666UcgC3+ZO/CevRxvLAOjpZEttJm90J2j/vDfGBsjnIcAkHDO42x1u/VvrDXJrWpGmmAZ0vBcW8Hg+6qhXNQngzSfMfID+eE9OBf7Ptj1flAea1WrfvNQPFDy0qlriusYjc7tL6tFmUgwzhfzI3V8xPOH1Bxmh5Cl92JOk8=</ds:SignatureValue>
+		<ds:KeyInfo>
+			<ds:X509Data>
+				<ds:X509Certificate>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</ds:X509Certificate>
+			</ds:X509Data>
+		</ds:KeyInfo>
+	</ds:Signature>
+	<samlp:Status xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
+		<samlp:StatusCode xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+	</samlp:Status>
+	<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ID="the-assertion-id" IssueInstant="2020-09-14T22:37:32Z" Version="2.0">
+		<saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+		<saml:Subject>
+			<saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">the-name-id</saml:NameID>
+			<saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
+				<saml:SubjectConfirmationData InResponseTo="id-abc" NotOnOrAfter="2020-09-14T22:47:32Z" Recipient="https://example.org/acs/post"/>
+			</saml:SubjectConfirmation>
+		</saml:Subject>
+		<saml:Conditions NotBefore="2020-09-14T22:27:32Z" NotOnOrAfter="2020-09-14T22:47:32Z">
+			<saml:AudienceRestriction>
+				<saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience>
+			</saml:AudienceRestriction>
+		</saml:Conditions>
+		<saml:AuthnStatement AuthnInstant="2020-09-14T22:37:32Z" SessionIndex="id-sessidx">
+			<saml:AuthnContext>
+				<saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml:AuthnContextClassRef>
+			</saml:AuthnContext>
+		</saml:AuthnStatement>
+	</saml:Assertion>
+</samlp:Response>
+	<saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">urn:mace:example.com:saml:roland:idp</saml:Issuer>
+	<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
+		<ds:SignedInfo>
+			<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+			<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
+			<ds:Reference URI="#attack-response-id">
+				<ds:Transforms>
+					<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
+					<ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
+				</ds:Transforms>
+				<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
+				<ds:DigestValue>ykldcjeUTA6xMqk+BUQy9hvraOo=</ds:DigestValue>
+			</ds:Reference>
+		</ds:SignedInfo>
+		<ds:SignatureValue>TF6666UcgC3+ZO/CevRxvLAOjpZEttJm90J2j/vDfGBsjnIcAkHDO42x1u/VvrDXJrWpGmmAZ0vBcW8Hg+6qhXNQngzSfMfID+eE9OBf7Ptj1flAea1WrfvNQPFDy0qlriusYjc7tL6tFmUgwzhfzI3V8xPOH1Bxmh5Cl92JOk8=</ds:SignatureValue>
+		<ds:KeyInfo>
+			<ds:X509Data>
+				<ds:X509Certificate>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</ds:X509Certificate>
+			</ds:X509Data>
+		</ds:KeyInfo>
+	</ds:Signature>
+	<samlp:Status xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
+		<samlp:StatusCode xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
+	</samlp:Status>
+	<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ID="the-assertion-id" IssueInstant="2020-09-14T22:37:32Z" Version="2.0">
+		<saml:Issuer>urn:mace:example.com:saml:roland:idp</saml:Issuer>
+		<saml:Subject>
+			<saml:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent">attack-name-id</saml:NameID>
+			<saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
+				<saml:SubjectConfirmationData InResponseTo="id-abc" NotOnOrAfter="2020-09-14T22:47:32Z" Recipient="https://example.org/acs/post"/>
+			</saml:SubjectConfirmation>
+		</saml:Subject>
+		<saml:Conditions NotBefore="2020-09-14T22:27:32Z" NotOnOrAfter="2020-09-14T22:47:32Z">
+			<saml:AudienceRestriction>
+				<saml:Audience>urn:mace:example.com:saml:roland:sp</saml:Audience>
+			</saml:AudienceRestriction>
+		</saml:Conditions>
+		<saml:AuthnStatement AuthnInstant="2020-09-14T22:37:32Z" SessionIndex="id-sessidx">
+			<saml:AuthnContext>
+				<saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml:AuthnContextClassRef>
+			</saml:AuthnContext>
+		</saml:AuthnStatement>
+	</saml:Assertion>
+</samlp:Response>