CVE-2024-32962

xml-crypto is an xml digital signature and encryption library for Node.js. In affected versions the default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of the w3 xmldsig-core-20080610 spec. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks. As a result xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />. xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes. An attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element. This vulnerability is combination of changes introduced to 4.0.0 on pull request 301 / commit c2b83f98 and has been addressed in version 6.0.0 with pull request 445 / commit 21201723d. Users are advised to upgrade. Users unable to upgrade may either check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation or set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

xml-crypto is an xml digital signature and encryption library for Node.js. In affected versions the default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of the w3 xmldsig-core-20080610 spec. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks. As a result xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />. xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes. An attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element. This vulnerability is combination of changes introduced to 4.0.0 on pull request 301 / commit c2b83f98 and has been addressed in version 6.0.0 with pull request 445 / commit 21201723d. Users are advised to upgrade. Users unable to upgrade may either check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation or set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

Summary

Default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of https://www.w3.org/TR/2008/REC-xmldsig-core-20080610/#sec-CoreValidation. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks.

Details

Affected xml-crypto versions between versions >= 4.0.0 and < 6.0.0.

xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />.

xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes.

Attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element.

Vulnerability is combination of changes introduced to 4.0.0 at

• https://github.com/node-saml/xml-crypto/pull/301
• https://github.com/node-saml/xml-crypto/commit/c2b83f984049edb68ad1d7c6ad0739ec92af11ca

Changes at PR provided default method to extract certificate from signed XML document.

• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L405-L414
• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L334

and changes at PR prefer output of that method to be used as certificate for signature verification even in the case when library is configured to use specific/pre-configured signingCert

• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L507

Name of the signingCert was changed later (but prior to 4.0.0 release) to publicCert:

• https://github.com/node-saml/xml-crypto/commit/78329fbae34c9b25ba25882604e960f506d7c0e7
• https://github.com/node-saml/xml-crypto/blob/78329fbae34c9b25ba25882604e960f506d7c0e7/lib/signed-xml.js#L507

Issue was fixed to 6.0.0 by disabling implicit usage of default getCertFromKeyInfo implementation:

• https://github.com/node-saml/xml-crypto/pull/445
• https://github.com/node-saml/xml-crypto/commit/21201723d2ca9bc11288f62cf72552b7d659b000

Possible workarounds for versions 4.x and 5.x:

• Check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation.
• Set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

PoC

https://github.com/node-saml/xml-crypto/discussions/399

Impact

An untrusted certificate can be used to pass a malicious XML payload through an improperly configured installation of xml-crypto.

xml-crypto is an xml digital signature and encryption library for Node.js. In affected versions the default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of the w3 xmldsig-core-20080610 spec. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks. As a result xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />. xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes. An attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element. This vulnerability is combination of changes introduced to 4.0.0 on pull request 301 / commit c2b83f98 and has been addressed in version 6.0.0 with pull request 445 / commit 21201723d. Users are advised to upgrade. Users unable to upgrade may either check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation or set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

xml-crypto is an xml digital signature and encryption library for Node.js. In affected versions the default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of the w3 xmldsig-core-20080610 spec. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks. As a result xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />. xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes. An attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element. This vulnerability is combination of changes introduced to 4.0.0 on pull request 301 / commit c2b83f98 and has been addressed in version 6.0.0 with pull request 445 / commit 21201723d. Users are advised to upgrade. Users unable to upgrade may either check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation or set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

Summary

Default configuration does not check authorization of the signer, it only checks the validity of the signature per section 3.2.2 of https://www.w3.org/TR/2008/REC-xmldsig-core-20080610/#sec-CoreValidation. As such, without additional validation steps, the default configuration allows a malicious actor to re-sign an XML document, place the certificate in a <KeyInfo /> element, and pass xml-crypto default validation checks.

Details

Affected xml-crypto versions between versions >= 4.0.0 and < 6.0.0.

xml-crypto trusts by default any certificate provided via digitally signed XML document's <KeyInfo />.

xml-crypto prefers to use any certificate provided via digitally signed XML document's <KeyInfo /> even if library was configured to use specific certificate (publicCert) for signature verification purposes.

Attacker can spoof signature verification by modifying XML document and replacing existing signature with signature generated with malicious private key (created by attacker) and by attaching that private key's certificate to <KeyInfo /> element.

Vulnerability is combination of changes introduced to 4.0.0 at

• https://github.com/node-saml/xml-crypto/pull/301
• https://github.com/node-saml/xml-crypto/commit/c2b83f984049edb68ad1d7c6ad0739ec92af11ca

Changes at PR provided default method to extract certificate from signed XML document.

• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L405-L414
• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L334

and changes at PR prefer output of that method to be used as certificate for signature verification even in the case when library is configured to use specific/pre-configured signingCert

• https://github.com/node-saml/xml-crypto/blob/c2b83f984049edb68ad1d7c6ad0739ec92af11ca/lib/signed-xml.js#L507

Name of the signingCert was changed later (but prior to 4.0.0 release) to publicCert:

• https://github.com/node-saml/xml-crypto/commit/78329fbae34c9b25ba25882604e960f506d7c0e7
• https://github.com/node-saml/xml-crypto/blob/78329fbae34c9b25ba25882604e960f506d7c0e7/lib/signed-xml.js#L507

Issue was fixed to 6.0.0 by disabling implicit usage of default getCertFromKeyInfo implementation:

• https://github.com/node-saml/xml-crypto/pull/445
• https://github.com/node-saml/xml-crypto/commit/21201723d2ca9bc11288f62cf72552b7d659b000

Possible workarounds for versions 4.x and 5.x:

• Check the certificate extracted via getCertFromKeyInfo against trusted certificates before accepting the results of the validation.
• Set xml-crypto's getCertFromKeyInfo to () => undefined forcing xml-crypto to use an explicitly configured publicCert or privateKey for signature verification.

PoC

https://github.com/node-saml/xml-crypto/discussions/399

Impact

An untrusted certificate can be used to pass a malicious XML payload through an improperly configured installation of xml-crypto.