URL Redirection to Untrusted Site in XWiki

@@ -38,7 +38,7 @@
 public class XWikiServletResponse implements XWikiResponse
 {
     private static final Logger LOGGER = LoggerFactory.getLogger(XWikiServletResponse.class);
-    private static final Pattern ABSOLUTE_URL_PATTERN = Pattern.compile("[a-z0-9]+://.*");
+    private static final Pattern ABSOLUTE_URL_PATTERN = Pattern.compile("[a-z0-9]+:/[/]?.*");
 
     private HttpServletResponse response;
 
@@ -71,6 +71,13 @@ public void sendRedirect(String redirect) throws IOException
             return;
         }
 
+        if (StringUtils.startsWith(redirect, "//")) {
+            LOGGER.warn("Possible phishing attack, attempting to redirect to [{}]. If this request is legitimate, "
+                + "use an actual absolute URL and pay attention to configure properly url.trustedDomains in "
+                + "xwiki.properties", redirect);
+            return;
+        }
+
         // check for trusted domains, only if the given location is an absolute URL.
         if (ABSOLUTE_URL_PATTERN.matcher(redirect).matches()) {
             if (!getURLSecurityManager().isDomainTrusted(new URL(redirect))) {

@@ -0,0 +1,123 @@
+/*
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package com.xpn.xwiki.web;
+
+import java.io.IOException;
+import java.net.URL;
+
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.ecs.wml.U;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.xwiki.component.manager.ComponentManager;
+import org.xwiki.test.annotation.BeforeComponent;
+import org.xwiki.test.junit5.mockito.ComponentTest;
+import org.xwiki.test.junit5.mockito.InjectMockComponents;
+import org.xwiki.test.junit5.mockito.MockComponent;
+import org.xwiki.test.mockito.MockitoComponentManager;
+import org.xwiki.url.URLSecurityManager;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * Tests for {@link XWikiServletResponse}.
+ *
+ * @version $Id$
+ */
+@ComponentTest
+class XWikiServletResponseTest
+{
+    @MockComponent
+    private URLSecurityManager urlSecurityManager;
+
+    private XWikiServletResponse servletResponse;
+    private HttpServletResponse httpServletResponse;
+
+    @BeforeComponent
+    void beforeComponent(MockitoComponentManager mockitoComponentManager) throws Exception
+    {
+        mockitoComponentManager.registerComponent(ComponentManager.class, "context", mockitoComponentManager);
+        Utils.setComponentManager(mockitoComponentManager);
+    }
+
+    @BeforeEach
+    void setup()
+    {
+        this.httpServletResponse = mock(HttpServletResponse.class);
+        this.servletResponse = new XWikiServletResponse(this.httpServletResponse);
+    }
+
+    @Test
+    void sendRedirect() throws IOException
+    {
+        this.servletResponse.sendRedirect("");
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+
+        this.servletResponse.sendRedirect("/xwiki/\n/something/");
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+
+        this.servletResponse.sendRedirect("//xwiki.org/xwiki/something/");
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+
+        String redirect = "http://xwiki.org/xwiki/something/";
+        URL redirectUrl = new URL(redirect);
+        when(this.urlSecurityManager.isDomainTrusted(redirectUrl)).thenReturn(false);
+        this.servletResponse.sendRedirect(redirect);
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+        verify(this.urlSecurityManager).isDomainTrusted(redirectUrl);
+
+        redirect = "http:/xwiki.com/xwiki/something/";
+        redirectUrl = new URL(redirect);
+        when(this.urlSecurityManager.isDomainTrusted(redirectUrl)).thenReturn(false);
+        this.servletResponse.sendRedirect(redirect);
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+        verify(this.urlSecurityManager).isDomainTrusted(redirectUrl);
+
+        redirect = "https://floo";
+        redirectUrl = new URL(redirect);
+        when(this.urlSecurityManager.isDomainTrusted(redirectUrl)).thenReturn(false);
+        this.servletResponse.sendRedirect(redirect);
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+        verify(this.urlSecurityManager).isDomainTrusted(redirectUrl);
+
+        redirect = "ftp://xwiki.org/xwiki/something/";
+        redirectUrl = new URL(redirect);
+        when(this.urlSecurityManager.isDomainTrusted(redirectUrl)).thenReturn(false);
+        this.servletResponse.sendRedirect(redirect);
+        verify(this.httpServletResponse, never()).sendRedirect(any());
+        verify(this.urlSecurityManager).isDomainTrusted(redirectUrl);
+
+        this.servletResponse.sendRedirect("/xwiki/something/");
+        verify(this.httpServletResponse).sendRedirect("/xwiki/something/");
+
+        redirect = "http://xwiki.org/foo/";
+        redirectUrl = new URL(redirect);
+        when(this.urlSecurityManager.isDomainTrusted(redirectUrl)).thenReturn(true);
+        this.servletResponse.sendRedirect(redirect);
+        verify(this.httpServletResponse).sendRedirect(redirect);
+        verify(this.urlSecurityManager).isDomainTrusted(redirectUrl);
+    }
+}
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