From 0603c0fbdfe028113431c65590b6e7e28929f6f6 Mon Sep 17 00:00:00 2001 From: Thomas Lenz Date: Fri, 23 Jun 2017 06:50:14 +0200 Subject: some small refactoring and code documentation --- utils/src/main/java/at/gv/egiz/dom/DOMUtils.java | 78 +++++++++++++++++++++- .../java/at/gv/egiz/slbinding/SLUnmarshaller.java | 52 +++++++-------- 2 files changed, 98 insertions(+), 32 deletions(-) (limited to 'utils/src/main/java/at/gv/egiz') diff --git a/utils/src/main/java/at/gv/egiz/dom/DOMUtils.java b/utils/src/main/java/at/gv/egiz/dom/DOMUtils.java index eae8f05e..2054021a 100644 --- a/utils/src/main/java/at/gv/egiz/dom/DOMUtils.java +++ b/utils/src/main/java/at/gv/egiz/dom/DOMUtils.java @@ -33,7 +33,8 @@ import java.io.StringWriter; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; -import javax.xml.parsers.ParserConfigurationException; +import javax.xml.parsers.ParserConfigurationException; +import javax.xml.stream.XMLStreamException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerException; @@ -47,7 +48,8 @@ import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.Text; import org.w3c.dom.bootstrap.DOMImplementationRegistry; -import org.w3c.dom.ls.DOMImplementationLS; +import org.w3c.dom.ls.DOMImplementationLS; +import org.xml.sax.SAXException; public final class DOMUtils { @@ -160,6 +162,76 @@ public final class DOMUtils { base64OutputStream.close(); return doc.createTextNode(outputStream.toString("ASCII")); - } + } + + /** + * Set XML parser features to {@link DocumentBuilderFactory} to prevent XXE, XEE and SSRF attacks + *
+ *
+ * These features are set by this method: + * + * + * + * @param dbf {@link DocumentBuilderFactory} on which the features should be registered + */ + public static void setXMLParserFlagsAgainstXXEAndSSRFAttacks(DocumentBuilderFactory dbf) { + try { + dbf.setFeature("http://xml.org/sax/features/external-general-entities", false); + dbf.setFeature("http://xml.org/sax/features/external-parameter-entities", false); + dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); + dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); + + } catch (ParserConfigurationException e) { + log.error("Can NOT set Xerces parser security features. -> XML parsing is possible insecure!!!! ", e); + + } + + } + + /** + * Parse an {@link InputStream} that contains a XML document into a {@link Document} + * This method set all features to prevent XXE, XEE and SSRF attacks + * + * These features are set by this method: + * + * + * @param is {@link InputStream} that contains a serialized XML document + * @return Deserialized {@link Document} from input XML + * @throws XMLStreamException XML parser has an error + * @throws IOException + */ + public static Document validateXMLAgainstXXEAndSSRFAttacks(InputStream is) throws XMLStreamException, IOException { + DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); + setXMLParserFlagsAgainstXXEAndSSRFAttacks(dbf); + + try { + //validate input stream + return dbf.newDocumentBuilder().parse(is); + + } catch (SAXException e) { + log.error("XML data validation FAILED with msg: " + e.getMessage(), e); + throw new XMLStreamException("XML data validation FAILED with msg: " + e.getMessage(), e); + + } catch (ParserConfigurationException e) { + log.error("XML data validation FAILED with msg: " + e.getMessage(), e); + throw new XMLStreamException("XML data validation FAILED with msg: " + e.getMessage(), e); + + } catch (IOException e) { + log.error("XML data validation FAILED with msg: " + e.getMessage(), e); + throw new XMLStreamException("XML data validation FAILED with msg: " + e.getMessage(), e); + + } + + } } diff --git a/utils/src/main/java/at/gv/egiz/slbinding/SLUnmarshaller.java b/utils/src/main/java/at/gv/egiz/slbinding/SLUnmarshaller.java index 2d1808c8..489c36d8 100644 --- a/utils/src/main/java/at/gv/egiz/slbinding/SLUnmarshaller.java +++ b/utils/src/main/java/at/gv/egiz/slbinding/SLUnmarshaller.java @@ -57,6 +57,7 @@ import org.slf4j.LoggerFactory; import org.xml.sax.SAXException; import at.gv.egiz.bku.utils.ClasspathURLStreamHandler; +import at.gv.egiz.dom.DOMUtils; import at.gv.egiz.validation.ReportingValidationEventHandler; public class SLUnmarshaller { @@ -241,43 +242,28 @@ public class SLUnmarshaller { * @throws JAXBException */ public Object unmarshal(StreamSource source) throws XMLStreamException, JAXBException { + Reader inputReader = source.getReader(); - ReportingValidationEventHandler validationEventHandler = new ReportingValidationEventHandler(); - Reader inputReader = source.getReader(); - - if (inputReader instanceof InputStreamReader) { - DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); - - try { - dbf.setFeature("http://xml.org/sax/features/external-general-entities", false); - dbf.setFeature("http://xml.org/sax/features/external-parameter-entities", false); - dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); - dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); - - } catch (ParserConfigurationException e) { - log.error("Can NOT set Xerces parser security features. -> XML parsing is possible insecure!!!! ", e); - - } - + /* Validate XML against XXE, XEE, and SSRF + * + * This pre-validation step is required because com.sun.xml.stream.sjsxp-1.0.2 XML stream parser library does not + * support all XML parser features to prevent these types of attacks + */ + if (inputReader instanceof InputStreamReader) { try { //create copy of input stream InputStreamReader isReader = (InputStreamReader) inputReader; String encoding = isReader.getEncoding(); byte[] backup = IOUtils.toByteArray(isReader, encoding); - //validate input stream - dbf.newDocumentBuilder().parse(new ByteArrayInputStream(backup)); + //validate input stream + DOMUtils.validateXMLAgainstXXEAndSSRFAttacks(new ByteArrayInputStream(backup)); //create new inputStreamReader for reak processing inputReader = new InputStreamReader(new ByteArrayInputStream(backup), encoding); - } catch (SAXException e) { - log.error("XML data validation FAILED with msg: " + e.getMessage(), e); - throw new XMLStreamException("XML data validation FAILED with msg: " + e.getMessage(), e); - - - } catch (ParserConfigurationException e) { + } catch (XMLStreamException e) { log.error("XML data validation FAILED with msg: " + e.getMessage(), e); throw new XMLStreamException("XML data validation FAILED with msg: " + e.getMessage(), e); @@ -294,20 +280,28 @@ public Object unmarshal(StreamSource source) throws XMLStreamException, JAXBExce } - //parse XML with original functionality + /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + * parse XML with original functionality + * + * This code implements the the original mocca XML processing by using + * com.sun.xml.stream.sjsxp-1.0.2 XML stream parser library. Currently, this library is required to get full + * security-layer specific XML processing. However, there this lib does not fully support XXE, XEE and SSRF + * prevention mechanisms (e.g.: XMLInputFactory.SUPPORT_DTD flag is not used) + * + * !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! + */ XMLInputFactory inputFactory = XMLInputFactory.newInstance(); //disallow DTD and external entities inputFactory.setProperty(XMLInputFactory.SUPPORT_DTD, false); inputFactory.setProperty("javax.xml.stream.isSupportingExternalEntities", false); - - - + XMLEventReader eventReader = inputFactory.createXMLEventReader(inputReader); RedirectEventFilter redirectEventFilter = new RedirectEventFilter(); XMLEventReader filteredReader = inputFactory.createFilteredReader(eventReader, redirectEventFilter); Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); + ReportingValidationEventHandler validationEventHandler = new ReportingValidationEventHandler(); unmarshaller.setEventHandler(validationEventHandler); unmarshaller.setListener(new RedirectUnmarshallerListener(redirectEventFilter)); -- cgit v1.2.3