Advisories for Npm/Xml-Crypto package

An attacker may be able to exploit this vulnerability to bypass authentication or authorization mechanisms in systems that rely on xml-crypto for verifying signed XML documents. The vulnerability allows an attacker to modify a valid signed XML message in a way that still passes signature verification checks. For example, it could be used to alter critical identity or access control attributes, enabling an attacker with a valid account to escalate …

An attacker may be able to exploit this vulnerability to bypass authentication or authorization mechanisms in systems that rely on xml-crypto for verifying signed XML documents. The vulnerability allows an attacker to modify a valid signed XML message in a way that still passes signature verification checks. For example, it could be used to alter critical identity or access control attributes, enabling an attacker to escalate privileges or impersonate another …

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.

Impact An attacker can inject an HMAC-SHA1 signature that is valid using only knowledge of the RSA public key. This allows bypassing signature validation. Patches has the fix. Workarounds The recommendation is to upgrade. In case that is not possible remove the 'http://www.w3.org/2000/09/xmldsig#hmac-sha1' entry from SignedXml.SignatureAlgorithms.