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GHSA-wc9j-gc65-3cm7

MediumCVSS 6.5 / 10
Published Aug 31, 2023·Last modified Feb 16, 2024
Affected Components(0)

No affected components available

Description

Impact

DDFFileParser and DefaultDDFFileValidator (and so ObjectLoader) are vulnerable to XXE Attacks.

DDF file is a LWM2M format used to store LWM2M object description.
Leshan users are impacted only if they parse untrusted DDF files (e.g. if they let external users provide their own model), in that case they MUST upgrade to fixed version. If you parse only trusted DDF file and validate only with trusted xml schema, upgrading is not mandatory.

Patches

This is fixed in v1.5.0 and 2.0.0-M13.

Workarounds

No easy way. Eventually writing your own DDFFileParser/DefaultDDFFileValidator (and so ObjectLoader) creating a DocumentBuilderFactory with :

// For DDFFileParser
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); // Disable DTDs
factory.setXIncludeAware(false); // Disable XML Inclusions
factory.setExpandEntityReferences(false); // disable expand entity reference nodes

// For DefaultDDFFileValidator
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
factory.setProperty(XMLConstants.ACCESS_EXTERNAL_DTD, "");
factory.setProperty(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");

References

  • https://owasp.org/www-community/vulnerabilities/XML_External_Entity_(XXE)_Processing
  • https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html
  • https://semgrep.dev/docs/cheat-sheets/java-xxe/
  • https://community.veracode.com/s/article/Java-Remediation-Guidance-for-XXE
Risk Scores
Base Score
6.5

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
6.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.57%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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