xml-crypto, Signature Verification Bypass, CVE-2023-XXXX (Critical)

How the CVE Works:

CVE-2023-XXXX is a critical vulnerability in the `xml-crypto` library, which is used for signing and verifying XML documents. The flaw arises due to improper handling of the `` node within XML signatures. Attackers can exploit this by injecting multiple `` nodes into a signed XML document. When the library processes the document, it fails to correctly validate the signature, allowing tampered content to pass verification. This can lead to authentication or authorization bypass, enabling privilege escalation or impersonation attacks. For example, an attacker could modify SAML assertions or other XML-based identity tokens to gain unauthorized access to systems.

DailyCVE Form:

Platform: xml-crypto
Version: <= 6.0.0
Vulnerability: Signature Bypass
Severity: Critical
Date: 2023-XX-XX

What Undercode Say:

Exploitation:

1. Crafting Malicious XML:

Attackers can inject multiple `` nodes into a signed XML document. For example:

<Signature>
<SignedInfo>
<Reference URI="fake">
<DigestValue>forged</DigestValue>
</Reference>
</SignedInfo>
<SignedInfo>
<Reference URI="real">
<DigestValue>valid</DigestValue>
</Reference>
</SignedInfo>
</Signature>

2. Bypassing Verification:

The `xml-crypto` library fails to enforce a single `` node, allowing the tampered document to pass signature checks.

3. Privilege Escalation:

By modifying SAML assertions or other XML-based tokens, attackers can impersonate users or escalate privileges.

Protection:

1. Upgrade:

Update `xml-crypto` to version 6.0.1 or later.

npm install [email protected]

2. Validation Script:

Implement a script to detect multiple `` nodes:

const xpath = require('xpath');
const dom = require('xmldom').DOMParser;
const xml = <code><Signature>...</Signature></code>; // Your XML
const doc = new dom().parseFromString(xml);
const signatureNodes = xpath.select("//[bash]", doc);
signatureNodes.forEach(signatureNode => {
const signedInfoNodes = xpath.select(".//[bash]", signatureNode);
if (signedInfoNodes.length > 1) {
console.error("Compromise Detected: Multiple SignedInfo Nodes");
}
});

3. Logging and Monitoring:

Monitor XML payloads for anomalies, such as unexpected `` nodes or tampered `` fields.

4. Input Sanitization:

Validate and sanitize XML inputs to prevent injection of malicious nodes.

5. Use Alternatives:

Consider using libraries with robust XML signature validation, such as xmldsigjs.

Commands:

Check installed version of xml-crypto:
```
npm list xml-crypto
```
Force upgrade to patched version:
```
npm install xml-crypto@latest --save
```

References:

bash
bash
bash
By following these steps, organizations can mitigate the risk posed by CVE-2023-XXXX and secure their XML-based authentication and authorization systems.

References:

Reported By: https://github.com/advisories/GHSA-9p8x-f768-wp2g
Extra Source Hub:
Undercode

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