Sign Up
Log In
Log In
or
Sign Up
Places
All Projects
Status Monitor
Collapse sidebar
systemsmanagement:Ardana:8:CentOS
python-pysaml2
0001-Fix-XML-Signature-Wrapping-XSW-vulnerabili...
Overview
Repositories
Revisions
Requests
Users
Attributes
Meta
File 0001-Fix-XML-Signature-Wrapping-XSW-vulnerabilities.patch of Package python-pysaml2
From 3d1d4b3cc2ade3fdcadf39111804d8abfdfc08a2 Mon Sep 17 00:00:00 2001 From: Ivan Kanakarakis <ivan.kanak@gmail.com> Date: Sat, 4 Jan 2020 00:39:47 +0200 Subject: [PATCH] Fix XML Signature Wrapping (XSW) vulnerabilities PySAML2 did not check that the signature in a SAML document is enveloped and thus XML signature wrapping (XSW) was effective. The signature information and the node/object that is signed can be in different places and thus the signature verification will succeed, but the wrong data will be used. This specifically affects the verification of assertions that have been signed. This was assigned CVE-2020-5390 Thanks to Alexey Sintsov and Yuri Goltsev from HERE Technologies to report this. + + + + + + + + In more detail: libxml2 follows the xmldsig-core specification. The xmldsig specification is way too general. saml-core reuses the xmldsig specification, but constrains it to use of specific facilities. The implementation of the SAML specification is responsible to enforce those constraints. libxml2/xmlsec1 are not aware of those constraints and thus process the document based on the full/general xmldsig rules. What is happening is the following: - xmldsig-core allows the signature-information and the data that was signed to be in different places. This works by setting the URI attribute of the Reference element. The URI attribute contains an optional identifier of the object being signed. (see "4.4.3 The Reference Element" -- https://www.w3.org/TR/xmldsig-core1/#sec-Reference) This identifier is actually a pointer that can be defined in many different ways; from XPath expressions that need to be executed(!), to a full URL that should be fetched(!) in order to recalculate the signature. - saml-core section "5.4 XML Signature Profile" defines constrains on the xmldsig-core facilities. It explicitly dictates that enveloped signatures are the only signatures allowed. This mean that: * Assertion/RequestType/ResponseType elements must have an ID attribute * signatures must have a single Reference element * the Reference element must have a URI attribute * the URI attribute contains an anchor * the anchor points to the enclosing element's ID attribute xmlsec1 does the right thing - it follows the reference URI pointer and validates the assertion. But, the pointer points to an assertion in another part of the document; not the assertion in which the signature is embedded/enveloped. SAML processing thinks that the signature is fine (that's what xmlsec1 said), and gets the assertion data from the assertion that contains the signature - but that assertion was never validated. The issue is that pysaml2 does not enforce the constrains on the signature validation facilities of xmldsig-core, that the saml-core spec defines. The solution is simple; all we need is to make sure that assertions with signatures (1) contain one reference element that (2) has a URI attribute (3) that is an anchor that (4) points to the assertion in which the signature is embedded. If those conditions are met then we're good, otherwise we should fail the verification. Signed-off-by: Ivan Kanakarakis <ivan.kanak@gmail.com> (cherry picked from commit 5e9d5acbcd8ae45c4e736ac521fd2df5b1c62e25) --- src/saml2/sigver.py | 49 ++++++++++++++++++++++++++++++++++++ tests/saml2_response_xsw.xml | 6 +++++ tests/test_xsw.py | 44 ++++++++++++++++++++++++++++++++ 3 files changed, 99 insertions(+) create mode 100644 tests/saml2_response_xsw.xml create mode 100644 tests/test_xsw.py diff --git a/src/saml2/sigver.py b/src/saml2/sigver.py index f89f347c..141334b6 100644 --- a/src/saml2/sigver.py +++ b/src/saml2/sigver.py @@ -1534,6 +1534,55 @@ class SecurityContext(object): # print(certs) + # saml-core section "5.4 XML Signature Profile" defines constrains on the + # xmldsig-core facilities. It explicitly dictates that enveloped signatures + # are the only signatures allowed. This mean that: + # * Assertion/RequestType/ResponseType elements must have an ID attribute + # * signatures must have a single Reference element + # * the Reference element must have a URI attribute + # * the URI attribute contains an anchor + # * the anchor points to the enclosing element's ID attribute + references = item.signature.signed_info.reference + signatures_must_have_a_single_reference_element = len(references) == 1 + the_Reference_element_must_have_a_URI_attribute = ( + signatures_must_have_a_single_reference_element + and hasattr(references[0], "uri") + ) + the_URI_attribute_contains_an_anchor = ( + the_Reference_element_must_have_a_URI_attribute + and references[0].uri.startswith("#") + and len(references[0].uri) > 1 + ) + the_anchor_points_to_the_enclosing_element_ID_attribute = ( + the_URI_attribute_contains_an_anchor + and references[0].uri == "#{id}".format(id=item.id) + ) + validators = { + "signatures must have a single reference element": ( + signatures_must_have_a_single_reference_element + ), + "the Reference element must have a URI attribute": ( + the_Reference_element_must_have_a_URI_attribute + ), + "the URI attribute contains an anchor": ( + the_URI_attribute_contains_an_anchor + ), + "the anchor points to the enclosing element ID attribute": ( + the_anchor_points_to_the_enclosing_element_ID_attribute + ), + } + if not all(validators.values()): + error_context = { + "message": "Signature failed to meet constraints on xmldsig", + "validators": validators, + "item ID": item.id, + "reference URI": item.signature.signed_info.reference[0].uri, + "issuer": _issuer, + "node name": node_name, + "xml document": decoded_xml, + } + raise SignatureError(error_context) + verified = False last_pem_file = None for _, pem_file in certs: diff --git a/tests/saml2_response_xsw.xml b/tests/saml2_response_xsw.xml new file mode 100644 index 00000000..3671eb48 --- /dev/null +++ b/tests/saml2_response_xsw.xml @@ -0,0 +1,6 @@ +<?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>MIICsDCCAhmgAwIBAgIJAJrzqSSwmDY9MA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNVBAYTAkFVMRMwEQYDVQQIEwpTb21lLVN0YXRlMSEwHwYDVQQKExhJbnRlcm5ldCBXaWRnaXRzIFB0eSBMdGQwHhcNMDkxMDA2MTk0OTQxWhcNMDkxMTA1MTk0OTQxWjBFMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEhMB8GA1UEChMYSW50ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDJg2cms7MqjniT8Fi/XkNHZNPbNVQyMUMXE9tXOdqwYCA1cc8vQdzkihscQMXy3iPw2cMggBu6gjMTOSOxECkuvX5ZCclKr8pXAJM5cY6gVOaVO2PdTZcvDBKGbiaNefiEw5hnoZomqZGp8wHNLAUkwtH9vjqqvxyS/vclc6k2ewIDAQABo4GnMIGkMB0GA1UdDgQWBBRePsKHKYJsiojE78ZWXccK9K4aJTB1BgNVHSMEbjBsgBRePsKHKYJsiojE78ZWXccK9K4aJaFJpEcwRTELMAkGA1UEBhMCQVUxEzARBgNVBAgTClNvbWUtU3RhdGUxITAfBgNVBAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZIIJAJrzqSSwmDY9MAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEFBQADgYEAJSrKOEzHO7TL5cy6h3qh+3+JAk8HbGBW+cbX6KBCAw/mzU8flK25vnWwXS3dv2FF3Aod0/S7AWNfKib5U/SA9nJaz/mWeF9S0farz9AQFc8/NSzAzaVq7YbM4F6f6N2FRl7GikdXRCed45j6mrPzGzk3ECbupFnqyREH3+ZPSdk=</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 new file mode 100644 index 00000000..9978c4d3 --- /dev/null +++ b/tests/test_xsw.py @@ -0,0 +1,44 @@ +from datetime import datetime +from unittest.mock import Mock +from unittest.mock import patch + +from saml2.config import config_factory +from saml2.response import authn_response +from saml2.sigver import SignatureError + +from dateutil import parser + +from pytest import raises + +from pathutils import dotname +from pathutils import full_path + + +XML_RESPONSE_XSW = full_path("saml2_response_xsw.xml") + + +class TestAuthnResponse: + def setup_class(self): + self.conf = config_factory("sp", dotname("server_conf")) + self.ar = authn_response(self.conf, "http://lingon.catalogix.se:8087/") + + @patch('saml2.response.validate_on_or_after', return_value=True) + def test_verify_signed_xsw(self, mock_validate_on_or_after): + self.ar.issue_instant_ok = Mock(return_value=True) + + with open(XML_RESPONSE_XSW) as fp: + xml_response = fp.read() + + self.ar.outstanding_queries = {"id12": "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.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 -- 2.26.2
Locations
Projects
Search
Status Monitor
Help
OpenBuildService.org
Documentation
API Documentation
Code of Conduct
Contact
Support
@OBShq
Terms
openSUSE Build Service is sponsored by
The Open Build Service is an
openSUSE project
.
Sign Up
Log In
Places
Places
All Projects
Status Monitor
