implement a workaround to fix XXE and SSRF problems in an old XMLStreamParser implementation of a third party library

4 files changed, 214 insertions, 1 deletions

diff --git a/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/MoccaHttpServletRequestWrapper.java b/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/MoccaHttpServletRequestWrapper.java
new file mode 100644
index 00000000..8901969d
--- /dev/null
+++ b/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/MoccaHttpServletRequestWrapper.java
@@ -0,0 +1,72 @@
+package at.gv.egiz.bku.online.filter;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+import javax.servlet.ReadListener;
+import javax.servlet.ServletInputStream;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
+
+import org.apache.commons.io.IOUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+import at.gv.egiz.bku.binding.HttpUtil;
+
+
+public class MoccaHttpServletRequestWrapper extends HttpServletRequestWrapper {
+
+	private static Logger log = LoggerFactory.getLogger(MoccaHttpServletRequestWrapper.class);
+	
+	private final byte[] body;
+	private final String charset;
+	
+	public MoccaHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
+		super(request);
+				
+		String ct = request.getHeader(HttpUtil.HTTP_HEADER_CONTENT_TYPE.toLowerCase());
+		charset = HttpUtil.getCharset(ct, true);
+		
+		byte[] result = null;
+		try {
+			 result = IOUtils.toByteArray(request.getReader(), charset);
+						
+		} catch (IOException e) {
+			log.error("Can not copy input stream!!!!!", e);
+			throw new IOException("Can not copy input stream!!!!!", e);
+			
+		} finally {
+			body = result;
+			
+		}
+	}
+	
+	public boolean isInputStreamAvailable() {
+		return (body != null && body.length > 0);
+		
+	}
+	
+	@Override
+	public BufferedReader getReader() throws IOException {
+		return new BufferedReader(new InputStreamReader(getInputStream(), charset));
+	    
+	}
+
+	@Override
+	public ServletInputStream getInputStream() throws IOException {
+		final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body);
+		return new ServletInputStream() {
+
+			@Override
+			public int read() throws IOException {
+				return byteArrayInputStream.read();
+			}
+        
+		};
+					
+	}
+}
diff --git a/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/StalSecurityFilter.java b/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/StalSecurityFilter.java
new file mode 100644
index 00000000..0e98cb79
--- /dev/null
+++ b/BKUOnline/src/main/java/at/gv/egiz/bku/online/filter/StalSecurityFilter.java
@@ -0,0 +1,122 @@
+package at.gv.egiz.bku.online.filter;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletInputStream;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.stream.XMLStreamException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.xml.sax.SAXException;
+
+
+public class StalSecurityFilter implements Filter {
+
+	private static Logger log = LoggerFactory.getLogger(StalSecurityFilter.class);
+	
+	@Override
+	public void init(FilterConfig filterConfig) throws ServletException {
+		log.info("Initialize STAL Service security filter");
+		
+	}
+
+	@Override
+	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+			throws IOException, ServletException {
+
+		if (request instanceof HttpServletRequest) {
+			try {
+				MoccaHttpServletRequestWrapper stalHttpReq = new MoccaHttpServletRequestWrapper((HttpServletRequest) request);		
+				
+				if (stalHttpReq.isInputStreamAvailable()) {
+					log.trace("Validate STAL request ... ");
+					validateStalRequest(stalHttpReq.getInputStream());
+					log.trace("Validate of STAL request completed");
+					
+				}
+			
+				chain.doFilter(stalHttpReq, response);
+				
+			} catch (XMLStreamException e) {
+				log.error("XML data validation FAILED with msg: " + e.getMessage(), e);
+				sendErrorToResponse(e, response);
+					
+			} catch (IOException e) {
+				log.error("Can not process InputStream from STAL request");
+				sendErrorToResponse(e, response);
+				
+			}				
+						
+		} else {
+			log.error("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
+			log.warn("STAL request is processed WITHOUT security checks!!!!");
+			log.error("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
+			chain.doFilter(request, response);
+			
+		}
+	}
+
+	@Override
+	public void destroy() {
+		// TODO Auto-generated method stub
+		
+	}
+
+	private void sendErrorToResponse(Exception e, ServletResponse response) throws IOException {
+		if (response instanceof HttpServletResponse) {
+			((HttpServletResponse)response).sendError(HttpServletResponse.SC_BAD_REQUEST, e.getMessage());
+			
+		} else
+			log.error("Can not response with http error message");
+		
+	}
+	
+	private void validateStalRequest(InputStream is) throws XMLStreamException, IOException {
+			
+		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);
+			
+		}
+    	    	        
+		try {        	
+			//validate input stream        	
+			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/BKUOnline/src/main/java/at/gv/egiz/mocca/id/DataURLServerServlet.java b/BKUOnline/src/main/java/at/gv/egiz/mocca/id/DataURLServerServlet.java
index 7dd2cd22..37889ae5 100644
--- a/BKUOnline/src/main/java/at/gv/egiz/mocca/id/DataURLServerServlet.java
+++ b/BKUOnline/src/main/java/at/gv/egiz/mocca/id/DataURLServerServlet.java
@@ -135,7 +135,6 @@ public class DataURLServerServlet extends HttpServlet {
         }
         
         SLUnmarshaller slUnmarshaller = new SLUnmarshaller();
-        
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         dbf.setNamespaceAware(true);
         dbf.setSchema(slUnmarshaller.getSlSchema());
@@ -153,6 +152,18 @@ public class DataURLServerServlet extends HttpServlet {
                 "(see http://www.w3.org/TR/xmldsig-bestpractices/#be-aware-schema-normalization)", e);
         }
         
+        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 SAX parser security features. -> XML parsing is possible insecure!!!! ", e);
+			
+		}
+        
+        
         DocumentBuilder documentBuilder;
         try {
           documentBuilder = dbf.newDocumentBuilder();
diff --git a/BKUOnline/src/main/webapp/WEB-INF/web.xml b/BKUOnline/src/main/webapp/WEB-INF/web.xml
index 5033cc5e..5779fc97 100644
--- a/BKUOnline/src/main/webapp/WEB-INF/web.xml
+++ b/BKUOnline/src/main/webapp/WEB-INF/web.xml
@@ -175,6 +175,14 @@
 		<filter-name>RequestIdFilter</filter-name>
 		<filter-class>at.gv.egiz.bku.online.webapp.TransactionIdFilter</filter-class>
 	</filter>
+	<filter>
+		<filter-name>StalSecurityFilter</filter-name>
+		<filter-class>at.gv.egiz.bku.online.filter.StalSecurityFilter</filter-class>
+	</filter>
+	<filter-mapping>
+		<filter-name>StalSecurityFilter</filter-name>
+		<servlet-name>STALService</servlet-name>
+	</filter-mapping>
 	<filter-mapping>
 		<filter-name>RequestIdFilter</filter-name>
 		<servlet-name>HTTPSecurityLayerServlet</servlet-name>