CERT/CC Vulnerability Note VU#475445

Overview

Multiple SAML libraries may incorrectly utilize the results of XML DOM traversal and canonicalization APIs in such a way that an attacker may be able to manipulate the SAML data without invalidating the cryptographic signature, allowing the attack to potentially bypass authentication to SAML service providers.

Description

CWE-287: Improper Authentication

Security Assertion Markup Language (SAML) is an XML-based markup language for security assertions regarding authentication and permissions, most commonly used for single sign-on (SSO) services.

Some XML DOM traversal and canonicalization APIs may be inconsistent in handling of comments within XML nodes. Incorrect use of these APIs by some SAML libraries results in incorrect parsing of the inner text of XML nodes such that any inner text after the comment is lost prior to cryptographically signing the SAML message. Text after the comment therefore has no impact on the signature on the SAML message.

A remote attacker can modify SAML content for a SAML service provider without invalidating the cryptographic signature, which may allow attackers to bypass primary authentication for the affected SAML service provider

The following CVEs are assigned:

CVE-2017-11427 - OneLogin’s "python-saml"
CVE-2017-11428 - OneLogin’s "ruby-saml"
CVE-2017-11429 - Clever’s "saml2-js"
CVE-2017-11430 - "OmniAuth-SAML"
CVE-2018-0489 - Shibboleth openSAML C++
CVE-2018-5387 - Wizkunde SAMLBase

More information is available in the researcher's blog post.

Impact

By modifying SAML content without invalidating the cryptographic signature, a remote, unauthenticated attacker may be able to bypass primary authentication for an affected SAML service provider.

Solution

Apply updates

Affected SAML service providers should update software to utilize the latest releases of affected SAML libraries. Please see the vendor list below for more information.

Vendor Information

475445

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Clever, Inc. Affected

Duo Security Affected

OmniAuth Affected

OneLogin Inc Affected

Pulse Secure Affected

Shibboleth Consortium Affected

Wizkunde B.V. Affected

AssureBridge Not Affected

Box Not Affected

CA Technologies Not Affected

Cisco Not Affected

ComponentSpace Pty Ltd Not Affected

Entr'ouvert Not Affected

ForgeRock Not Affected

GitHub Not Affected

Google Not Affected

Microsoft Not Affected

Okta Inc. Not Affected

Ping Identity Not Affected

Pivotal Software, Inc. Not Affected

SAML (golang) Not Affected

Tools4Ever Not Affected

VMware Not Affected

Danish e-Infrastructure Cooperation (WAYF) Unknown

GitLab Inc. Unknown

SSO Easy Unknown

View all 26 vendors View less vendors

CVSS Metrics

Group	Score	Vector
Base	6.3	AV:N/AC:M/Au:S/C:C/I:N/A:N
Temporal	4.9	E:POC/RL:OF/RC:C
Environmental	4.9	CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND

References

Acknowledgements

Thanks to Kelby Ludwig of Duo Security for reporting this vulnerability.

This document was written by Garret Wassermann.

Other Information

CVE IDs:	CVE-2017-11427, CVE-2017-11428, CVE-2017-11429, CVE-2017-11430, CVE-2018-0489, CVE-2018-5387
Date Public:	2018-02-27
Date First Published:	2018-02-27
Date Last Updated:	2018-06-05 18:02 UTC
Document Revision:	121

Software Engineering Institute

CERT Coordination Center

Multiple SAML libraries may allow authentication bypass via incorrect XML canonicalization and DOM traversal

Vulnerability Note VU#475445