github · atorralba · May 4, 2022 · Apr 9, 2022 · Apr 11, 2022 · Apr 19, 2022
@@ -377,3 +377,26 @@ class RequestDispatchMethod extends Method {
     this.hasName(["forward", "include"])
   }
 }
+
+/**
+ * The interface `javax.servlet.ServletContext`.
+ */
+class ServletContext extends RefType {
+  ServletContext() { this.hasQualifiedName("javax.servlet", "ServletContext") }
+}
+
+/** The `getResource` method of `ServletContext`. */
+class GetServletResourceMethod extends Method {
+  GetServletResourceMethod() {
+    this.getDeclaringType() instanceof ServletContext and
+    this.hasName("getResource")
+  }
+}
+
+/** The `getResourceAsStream` method of `ServletContext`. */
+class GetServletResourceAsStreamMethod extends Method {
+  GetServletResourceAsStreamMethod() {
+    this.getDeclaringType() instanceof ServletContext and
+    this.hasName("getResourceAsStream")
+  }
+}
@@ -0,0 +1,18 @@
+// BAD: no URI validation
+URL url = request.getServletContext().getResource(requestUrl);
+url = getClass().getResource(requestUrl);
+InputStream in = url.openStream();
+
+InputStream in = request.getServletContext().getResourceAsStream(requestPath);
+in = getClass().getClassLoader().getResourceAsStream(requestPath);
+
+// GOOD: check for a trusted prefix, ensuring path traversal is not used to erase that prefix:
+// (alternatively use `Path.normalize` instead of checking for `..`)
+if (!requestPath.contains("..") && requestPath.startsWith("/trusted")) {
+	InputStream in = request.getServletContext().getResourceAsStream(requestPath);
+}
+
+Path path = Paths.get(requestUrl).normalize().toRealPath();
+if (path.startsWith("/trusted")) {
+	URL url = request.getServletContext().getResource(path.toString());
+}
@@ -36,6 +36,13 @@ attacks. It also shows how to remedy the problem by validating the user input.
 
 <sample src="UnsafeServletRequestDispatch.java" />
 
+<p>The following examples show an HTTP request parameter or request path being used directly to
+retrieve a resource of a Java EE application without validating the input, which allows sensitive
+file exposure attacks. It also shows how to remedy the problem by validating the user input.
+</p>
+
+<sample src="UnsafeResourceGet.java" />
+
 </example>
 <references>
 <li>File Disclosure:
@@ -47,5 +54,8 @@ attacks. It also shows how to remedy the problem by validating the user input.
 <li>Micro Focus:
   <a href="https://vulncat.fortify.com/en/detail?id=desc.dataflow.java.file_disclosure_j2ee">File Disclosure: J2EE</a>
 </li>
+<li>CVE-2015-5174:
+  <a href="https://vuldb.com/?id.81084">Apache Tomcat 6.0/7.0/8.0/9.0 Servletcontext getResource/getResourceAsStream/getResourcePaths Path Traversal</a>
+</li>
 </references>
 </qhelp>
@@ -14,6 +14,7 @@ import java
 import UnsafeUrlForward
 import semmle.code.java.dataflow.FlowSources
 import semmle.code.java.dataflow.TaintTracking
+import experimental.semmle.code.java.frameworks.Jsf
 import experimental.semmle.code.java.PathSanitizer
 import DataFlow::PathGraph
 
@@ -43,6 +44,20 @@ class UnsafeUrlForwardFlowConfig extends TaintTracking::Configuration {
   override DataFlow::FlowFeature getAFeature() {
     result instanceof DataFlow::FeatureHasSourceCallContext
   }
+
+  override predicate isAdditionalTaintStep(DataFlow::Node prev, DataFlow::Node succ) {
+    exists(MethodAccess ma |
+      (
+        ma.getMethod() instanceof GetServletResourceMethod or
+        ma.getMethod() instanceof GetFacesResourceMethod or
+        ma.getMethod() instanceof GetClassResourceMethod or
+        ma.getMethod() instanceof GetClassLoaderResourceMethod or
+        ma.getMethod() instanceof GetWildflyResourceMethod
+      ) and
+      ma.getArgument(0) = prev.asExpr() and
+      ma = succ.asExpr()
+    )
+  }
 }
 
 from DataFlow::PathNode source, DataFlow::PathNode sink, UnsafeUrlForwardFlowConfig conf

@@ -1,7 +1,9 @@
 import java
+private import experimental.semmle.code.java.frameworks.Jsf
 private import semmle.code.java.dataflow.ExternalFlow
 private import semmle.code.java.dataflow.FlowSources
 private import semmle.code.java.dataflow.StringPrefixes
+private import semmle.code.java.frameworks.javaee.ejb.EJBRestrictions
 
 /** A sink for unsafe URL forward vulnerabilities. */
 abstract class UnsafeUrlForwardSink extends DataFlow::Node { }
@@ -19,6 +21,84 @@ private class RequestDispatcherSink extends UnsafeUrlForwardSink {
   }
 }
 
+/** The `getResource` method of `Class`. */
+class GetClassResourceMethod extends Method {
+  GetClassResourceMethod() {
+    this.getDeclaringType() instanceof TypeClass and
+    this.hasName("getResource")
+  }
+}
+
+/** The `getResourceAsStream` method of `Class`. */
+class GetClassResourceAsStreamMethod extends Method {
+  GetClassResourceAsStreamMethod() {
+    this.getDeclaringType() instanceof TypeClass and
+    this.hasName("getResourceAsStream")
+  }
+}
+
+/** The `getResource` method of `ClassLoader`. */
+class GetClassLoaderResourceMethod extends Method {
+  GetClassLoaderResourceMethod() {
+    this.getDeclaringType() instanceof ClassLoaderClass and
+    this.hasName("getResource")
+  }
+}
+
+/** The `getResourceAsStream` method of `ClassLoader`. */
+class GetClassLoaderResourceAsStreamMethod extends Method {
+  GetClassLoaderResourceAsStreamMethod() {
+    this.getDeclaringType() instanceof ClassLoaderClass and
+    this.hasName("getResourceAsStream")
+  }
+}
+
+/** The JBoss class `FileResourceManager`. */
+class FileResourceManager extends RefType {
+  FileResourceManager() {
+    this.hasQualifiedName("io.undertow.server.handlers.resource", "FileResourceManager")
+  }
+}
+
+/** The JBoss method `getResource` of `FileResourceManager`. */
+class GetWildflyResourceMethod extends Method {
+  GetWildflyResourceMethod() {
+    this.getDeclaringType().getASupertype*() instanceof FileResourceManager and
+    this.hasName("getResource")
+  }
+}
+
+/** The JBoss class `VirtualFile`. */
+class VirtualFile extends RefType {
+  VirtualFile() { this.hasQualifiedName("org.jboss.vfs", "VirtualFile") }
+}
+
+/** The JBoss method `getChild` of `FileResourceManager`. */
+class GetVirtualFileChildMethod extends Method {
+  GetVirtualFileChildMethod() {
+    this.getDeclaringType().getASupertype*() instanceof VirtualFile and
+    this.hasName("getChild")
+  }
+}
+
+/** An argument to `getResource()` or `getResourceAsStream()`. */
+private class GetResourceSink extends UnsafeUrlForwardSink {
+  GetResourceSink() {
+    sinkNode(this, "open-url")
+    or
+    exists(MethodAccess ma |
+      (
+        ma.getMethod() instanceof GetServletResourceAsStreamMethod or
+        ma.getMethod() instanceof GetFacesResourceAsStreamMethod or
+        ma.getMethod() instanceof GetClassResourceAsStreamMethod or
+        ma.getMethod() instanceof GetClassLoaderResourceAsStreamMethod or
+        ma.getMethod() instanceof GetVirtualFileChildMethod
+      ) and
+      ma.getArgument(0) = this.asExpr()
+    )
+  }
+}
+
 /** An argument to `new ModelAndView` or `ModelAndView.setViewName`. */
 private class SpringModelAndViewSink extends UnsafeUrlForwardSink {
   SpringModelAndViewSink() {
@@ -80,15 +160,18 @@ private class ServletGetPathSource extends SourceModelCsv {
   }
 }
 
-/** Taint model related to `java.nio.file.Path`. */
+/** Taint model related to `java.nio.file.Path` and `io.undertow.server.handlers.resource.Resource`. */
 private class FilePathFlowStep extends SummaryModelCsv {
   override predicate row(string row) {
     row =
       [
         "java.nio.file;Paths;true;get;;;Argument[0..1];ReturnValue;taint",
         "java.nio.file;Path;true;resolve;;;Argument[-1..0];ReturnValue;taint",
         "java.nio.file;Path;true;normalize;;;Argument[-1];ReturnValue;taint",
-        "java.nio.file;Path;true;toString;;;Argument[-1];ReturnValue;taint"
+        "java.nio.file;Path;true;toString;;;Argument[-1];ReturnValue;taint",
+        "io.undertow.server.handlers.resource;Resource;true;getFile;;;Argument[-1];ReturnValue;taint",
+        "io.undertow.server.handlers.resource;Resource;true;getFilePath;;;Argument[-1];ReturnValue;taint",
+        "io.undertow.server.handlers.resource;Resource;true;getPath;;;Argument[-1];ReturnValue;taint"
       ]
   }
 }
@@ -0,0 +1,34 @@
+/**
+ * Provides classes and predicates for working with the Java Server Faces (JSF).
+ */
+
+import java
+
+/**
+ * The JSF class `ExternalContext` for processing HTTP requests.
+ */
+class ExternalContext extends RefType {
+  ExternalContext() {
+    this.hasQualifiedName(["javax.faces.context", "jakarta.faces.context"], "ExternalContext")
+  }
+}
+
+/**
+ * The method `getResource()` declared in JSF `ExternalContext`.
+ */
+class GetFacesResourceMethod extends Method {
+  GetFacesResourceMethod() {
+    this.getDeclaringType().getASupertype*() instanceof ExternalContext and
+    this.hasName("getResource")
+  }
+}
+
+/**
+ * The method `getResourceAsStream()` declared in JSF `ExternalContext`.
+ */
+class GetFacesResourceAsStreamMethod extends Method {
+  GetFacesResourceAsStreamMethod() {
+    this.getDeclaringType().getASupertype*() instanceof ExternalContext and
+    this.hasName("getResourceAsStream")
+  }
+}