Fix: Harden FreeMarker against SSTI (#705)

* fix: SSTI freemarker

* fix: Harden FreeMarker SSTI

Author: AT190510-Cuong

template/fr.opensagres.xdocreport.template.freemarker/src/main/java/fr/opensagres/xdocreport/template/freemarker/FreemarkerTemplateEngine.java

@@ -197,6 +197,21 @@ public void setFreemarkerConfiguration( Configuration freemarkerConfiguration )
         {
         }
         this.freemarkerConfiguration.setLocalizedLookup( false );
+        
+        // Security fix: Block dangerous class instantiation via ?new operator to prevent SSTI attacks
+        // 
+        // This setting prevents Server-Side Template Injection (SSTI) attacks where malicious users
+        // By setting NEW_BUILTIN_CLASS_RESOLVER_KEY to "safer", FreeMarker will block instantiation
+        // of dangerous classes while still allowing legitimate template operations.
+        try
+        {
+            this.freemarkerConfiguration.setSetting( Configuration.NEW_BUILTIN_CLASS_RESOLVER_KEY, "safer" );
+        }
+        catch ( Exception e )
+        {
+            // Ignore configuration errors to maintain compatibility with older FreeMarker versions
+            // that might not support this security setting
+        }
     }
 
     public void extractFields( Reader reader, String entryName, FieldsExtractor extractor )

template/fr.opensagres.xdocreport.template.freemarker/src/test/java/fr/opensagres/xdocreport/template/freemarker/FreemarkerTemplateEngineSecurityTestCase.java

@@ -0,0 +1,67 @@
+package fr.opensagres.xdocreport.template.freemarker;
+
+import java.io.Reader;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.io.Writer;
+
+import junit.framework.TestCase;
+import fr.opensagres.xdocreport.core.XDocReportException;
+import fr.opensagres.xdocreport.template.IContext;
+import freemarker.template.Configuration;
+import freemarker.template.TemplateException;
+
+/**
+ * Test case to verify security fixes for Server-Side Template Injection (SSTI) vulnerabilities
+ * in the FreeMarker template engine.
+ */
+public class FreemarkerTemplateEngineSecurityTestCase
+    extends TestCase
+{
+
+    /**
+     * Test that legitimate template operations still work after security fix.
+     */
+    public void testLegitimateTemplateOperationsStillWork()
+        throws Exception
+    {
+        FreemarkerTemplateEngine templateEngine = new FreemarkerTemplateEngine();
+        
+        // Test basic variable substitution
+        String legitimateTemplate = "Hello ${name}!";
+        Reader reader = new StringReader( legitimateTemplate );
+        Writer writer = new StringWriter();
+        IContext context = templateEngine.createContext();
+        context.put( "name", "World" );
+
+        templateEngine.process( "", context, reader, writer );
+        assertEquals( "Hello World!", writer.toString() );
+    }
+
+
+    /**
+     * Test protection against SSTI payload with freemarker.template.utility.Execute.
+     */
+    public void testSSTIProtectionAgainstExecutePayload()
+        throws Exception
+    {
+        FreemarkerTemplateEngine templateEngine = new FreemarkerTemplateEngine();
+        
+        String maliciousTemplate ="${\"freemarker.template.utility.Execute\"?new()(\"whoami\")}";
+        Reader reader = new StringReader( maliciousTemplate );
+        Writer writer = new StringWriter();
+        IContext context = templateEngine.createContext();
+
+        try
+        {
+            templateEngine.process( "", context, reader, writer );
+            fail( "Security fix failed: Execute payload should be blocked" );
+        }
+        catch ( XDocReportException e )
+        {
+            assertTrue( "Expected security-related exception", 
+                       e.getCause() instanceof TemplateException );
+        }
+    }
+}
+