Java: make a separate threat model kind for reverse DNS sources

docs/codeql/reusables/threat-model-description.rst

@@ -4,7 +4,16 @@ A threat model is a named class of dataflow sources that can be enabled or disab
 
 The ``kind`` property of the ``sourceModel`` determines which threat model a source is associated with. There are two main categories:
 
-- ``remote`` which represents requests and responses from the network.
-- ``local`` which represents data from local files (``file``), command-line arguments (``commandargs``), database reads (``database``), and environment variables(``environment``).
+- ``remote`` which represents requests (``request``) and responses (``response``) from the network.
+- ``local`` which represents data from local files (``file``), command-line arguments (``commandargs``), database reads (``database``), environment variables(``environment``) and Windows registry values ("windows-registry"). Currently, Windows registry values are used by C# only.
+
+Note that subcategories can be turned included or excluded separately, so you can specify ``local`` without ``database``, or just ``commandargs`` and ``environment`` without the rest of ``local``.
+
+The less commonly used categories are:
+
+- ``android`` which represents reads from external files in Android (``android-external-storage-dir``) and parameter of an entry-point method declared in a ``ContentProvider`` class (``contentprovider``). Currently only used by Java/Kotlin.
+- ``database-access-result`` which represents a database access. Currently only used by JavaScript.
+- ``file-write`` which represents opening a file in write mode. Currently only used in C#.
+- ``reverse-dns`` which represents reverse DNS lookups. Currently only used in Java.
 
 When running a CodeQL analysis, the ``remote`` threat model is included by default. You can optionally include other threat models as appropriate when using the CodeQL CLI and in GitHub code scanning. For more information, see `Analyzing your code with CodeQL queries <https://docs.github.com/code-security/codeql-cli/getting-started-with-the-codeql-cli/analyzing-your-code-with-codeql-queries#including-model-packs-to-add-potential-sources-of-tainted-data>`__ and `Customizing your advanced setup for code scanning <https://docs.github.com/code-security/code-scanning/creating-an-advanced-setup-for-code-scanning/customizing-your-advanced-setup-for-code-scanning#extending-codeql-coverage-with-threat-models>`__.

java/ql/lib/change-notes/2024-06-14-reverse-dns-separate-threat-model-kind.md

@@ -0,0 +1,4 @@
+---
+category: majorAnalysis
+---
+* We previously considered reverse DNS resolutions (IP address -> domain name) as sources of untrusted data, since compromised/malicious DNS servers could potentially return malicious responses to arbitrary requests. We have now removed this source from the default set of untrusted sources and made a new threat model kind for them, called "reverse-dns". You can optionally include other threat models as appropriate when using the CodeQL CLI and in GitHub code scanning. For more information, see [Analyzing your code with CodeQL queries](https://docs.github.com/code-security/codeql-cli/getting-started-with-the-codeql-cli/analyzing-your-code-with-codeql-queries#including-model-packs-to-add-potential-sources-of-tainted-data>) and [Customizing your advanced setup for code scanning](https://docs.github.com/code-security/code-scanning/creating-an-advanced-setup-for-code-scanning/customizing-your-advanced-setup-for-code-scanning#extending-codeql-coverage-with-threat-models).

java/ql/lib/semmle/code/java/dataflow/FlowSources.qll

@@ -119,21 +119,6 @@ private predicate variableStep(Expr tracked, VarAccess sink) {
   )
 }
 
-private class ReverseDnsSource extends RemoteFlowSource {
-  ReverseDnsSource() {
-    // Try not to trigger on `localhost`.
-    exists(MethodCall m | m = this.asExpr() |
-      m.getMethod() instanceof ReverseDnsMethod and
-      not exists(MethodCall l |
-        (variableStep(l, m.getQualifier()) or l = m.getQualifier()) and
-        (l.getMethod().getName() = "getLocalHost" or l.getMethod().getName() = "getLoopbackAddress")
-      )
-    )
-  }
-
-  override string getSourceType() { result = "reverse DNS lookup" }
-}
-
 private class MessageBodyReaderParameterSource extends RemoteFlowSource {
   MessageBodyReaderParameterSource() {
     exists(MessageBodyReaderRead m |
@@ -388,6 +373,24 @@ class AndroidJavascriptInterfaceMethodParameter extends RemoteFlowSource {
   }
 }
 
+/** A node with input that comes from a reverse DNS lookup. */
+abstract class ReverseDnsUserInput extends UserInput {
+  override string getThreatModel() { result = "reverse-dns" }
+}
+
+private class ReverseDnsSource extends ReverseDnsUserInput {
+  ReverseDnsSource() {
+    // Try not to trigger on `localhost`.
+    exists(MethodCall m | m = this.asExpr() |
+      m.getMethod() instanceof ReverseDnsMethod and
+      not exists(MethodCall l |
+        (variableStep(l, m.getQualifier()) or l = m.getQualifier()) and
+        (l.getMethod().getName() = "getLocalHost" or l.getMethod().getName() = "getLoopbackAddress")
+      )
+    )
+  }
+}
+
 /**
  * A data flow source node for an API, which should be considered
  * supported for a modeling perspective.

java/ql/test/library-tests/dataflow/taintsources/A.java

@@ -43,7 +43,7 @@ public void test(ResultSet rs) throws SQLException {
     };
     sink(new URL("test").openConnection().getInputStream()); // $hasRemoteValueFlow
     sink(new Socket("test", 1234).getInputStream()); // $hasRemoteValueFlow
-    sink(InetAddress.getByName("test").getHostName()); // $hasRemoteValueFlow
+    sink(InetAddress.getByName("test").getHostName()); // $hasReverseDnsValueFlow
 
     sink(System.in); // $hasLocalValueFlow
     sink(new FileInputStream("test")); // $hasLocalValueFlow

java/ql/test/library-tests/dataflow/taintsources/local.ql

@@ -2,24 +2,20 @@ import java
 import semmle.code.java.dataflow.FlowSources
 import TestUtilities.InlineExpectationsTest
 
-class LocalSource extends DataFlow::Node instanceof UserInput {
-  LocalSource() { not this instanceof RemoteFlowSource }
-}
-
 predicate isTestSink(DataFlow::Node n) {
   exists(MethodCall ma | ma.getMethod().hasName("sink") | n.asExpr() = ma.getAnArgument())
 }
 
 module LocalValueConfig implements DataFlow::ConfigSig {
-  predicate isSource(DataFlow::Node n) { n instanceof LocalSource }
+  predicate isSource(DataFlow::Node n) { n instanceof LocalUserInput }
 
   predicate isSink(DataFlow::Node n) { isTestSink(n) }
 }
 
 module LocalValueFlow = DataFlow::Global<LocalValueConfig>;
 
 module LocalTaintConfig implements DataFlow::ConfigSig {
-  predicate isSource(DataFlow::Node n) { n instanceof LocalSource }
+  predicate isSource(DataFlow::Node n) { n instanceof LocalUserInput }
 
   predicate isSink(DataFlow::Node n) { isTestSink(n) }
 }

java/ql/test/library-tests/dataflow/taintsources/reversedns.expected

@@ -0,0 +1,2 @@
+failures
+testFailures

java/ql/test/library-tests/dataflow/taintsources/reversedns.ql

@@ -0,0 +1,47 @@
+import java
+import semmle.code.java.dataflow.FlowSources
+import TestUtilities.InlineExpectationsTest
+
+predicate isTestSink(DataFlow::Node n) {
+  exists(MethodCall ma | ma.getMethod().hasName("sink") | n.asExpr() = ma.getAnArgument())
+}
+
+module ReverseDnsValueConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node n) { n instanceof ReverseDnsUserInput }
+
+  predicate isSink(DataFlow::Node n) { isTestSink(n) }
+}
+
+module ReverseDnsValueFlow = DataFlow::Global<ReverseDnsValueConfig>;
+
+module ReverseDnsTaintConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node n) { n instanceof ReverseDnsUserInput }
+
+  predicate isSink(DataFlow::Node n) { isTestSink(n) }
+}
+
+module ReverseDnsTaintFlow = TaintTracking::Global<ReverseDnsTaintConfig>;
+
+module ReverseDnsFlowTest implements TestSig {
+  string getARelevantTag() { result = ["hasReverseDnsValueFlow", "hasReverseDnsTaintFlow"] }
+
+  predicate hasActualResult(Location location, string element, string tag, string value) {
+    tag = "hasReverseDnsValueFlow" and
+    exists(DataFlow::Node sink | ReverseDnsValueFlow::flowTo(sink) |
+      sink.getLocation() = location and
+      element = sink.toString() and
+      value = ""
+    )
+    or
+    tag = "hasReverseDnsTaintFlow" and
+    exists(DataFlow::Node src, DataFlow::Node sink |
+      ReverseDnsTaintFlow::flow(src, sink) and not ReverseDnsValueFlow::flow(src, sink)
+    |
+      sink.getLocation() = location and
+      element = sink.toString() and
+      value = ""
+    )
+  }
+}
+
+import MakeTest<ReverseDnsFlowTest>

java/ql/test/query-tests/security/CWE-022/semmle/tests/Test.java

@@ -5,12 +5,14 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.net.InetAddress;
 import java.net.URL;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
+
+import javax.servlet.http.HttpServletRequest;
 import javax.xml.transform.stream.StreamResult;
+
 import org.apache.commons.io.FileUtils;
 import org.apache.tools.ant.AntClassLoader;
 import org.apache.tools.ant.DirectoryScanner;
@@ -24,10 +26,10 @@
 
 public class Test {
 
-    private InetAddress address;
+    private HttpServletRequest request;
 
     public Object source() {
-        return address.getHostName();
+        return request.getParameter("source");
     }
 
     void test() throws IOException {
@@ -166,8 +168,8 @@ void test(AntClassLoader acl) {
         new LargeText((File) source(), null, false, false); // $ hasTaintFlow
     }
 
-    void doGet6(String root, InetAddress address) throws IOException {
-        String temp = address.getHostName();
+    void doGet6(String root, HttpServletRequest request) throws IOException {
+        String temp = request.getParameter("source");
         // GOOD: Use `contains` and `startsWith` to check if the path is safe
         if (!temp.contains("..") && temp.startsWith(root + "/")) {
             File file = new File(temp);

shared/mad/codeql/mad/ModelValidation.qll

@@ -118,7 +118,7 @@ module KindValidation<KindValidationConfigSig Config> {
       this =
         [
           // shared
-          "local", "remote", "file", "commandargs", "database", "environment",
+          "local", "remote", "file", "commandargs", "database", "environment", "reverse-dns",
           // Java
           "android-external-storage-dir", "contentprovider",
           // C#

shared/threat-models/ext/threat-model-grouping.model.yml

@@ -21,3 +21,10 @@ extensions:
       # Android threat models
       - ["android-external-storage-dir", "android"]
       - ["contentprovider", "android"]
+
+      # Threat models that are not grouped with any other threat models.
+      # (Note that all threat models are a child of "all" implicitly, and we
+      # make it explicit here just to make sure all threat models are listed.)
+      - ["database-access-result", "all"]
+      - ["file-write", "all"]
+      - ["reverse-dns", "all"]