C++: Add support for SAXParser in the query.

2026-04-29 10:45:15 +02:00 · 2022-04-28 16:08:41 +01:00
parent 4e2344c488
commit 2ccd5a5531
3 changed files with 65 additions and 28 deletions
--- a/cpp/ql/src/Security/CWE/CWE-611/XXE.ql
+++ b/cpp/ql/src/Security/CWE/CWE-611/XXE.ql
@@ -57,42 +57,51 @@ class XercesDOMParserClass extends Class {
 }

 /**
- * Gets a valid flow state for `XercesDOMParser` flow.
+ * The `SAXParser` class.
+ */
+class SAXParser extends Class {
+  SAXParser() { this.hasName("SAXParser") }
+}
+
+/**
+ * Gets a valid flow state for `AbstractDOMParser` or `SAXParser` flow.
 *
- * These flow states take the form `XercesDOM-A-B`, where:
+ * These flow states take the form `Xerces-A-B`, where:
 *  - A is 1 if `setDisableDefaultEntityResolution` is `true`, 0 otherwise.
 *  - B is 1 if `setCreateEntityReferenceNodes` is `true`, 0 otherwise.
 */
-predicate encodeXercesDOMFlowState(
+predicate encodeXercesFlowState(
  string flowstate, int disabledDefaultEntityResolution, int createEntityReferenceNodes
 ) {
-  flowstate = "XercesDOM-0-0" and
+  flowstate = "Xerces-0-0" and
  disabledDefaultEntityResolution = 0 and
  createEntityReferenceNodes = 0
  or
-  flowstate = "XercesDOM-0-1" and
+  flowstate = "Xerces-0-1" and
  disabledDefaultEntityResolution = 0 and
  createEntityReferenceNodes = 1
  or
-  flowstate = "XercesDOM-1-0" and
+  flowstate = "Xerces-1-0" and
  disabledDefaultEntityResolution = 1 and
  createEntityReferenceNodes = 0
  or
-  flowstate = "XercesDOM-1-1" and
+  flowstate = "Xerces-1-1" and
  disabledDefaultEntityResolution = 1 and
  createEntityReferenceNodes = 1
 }

 /**
- * A flow state representing the configuration of a `XercesDOMParser` object.
+ * A flow state representing the configuration of a `AbstractDOMParser` or
+ * `SAXParser` object.
 */
-class XercesDOMParserFlowState extends XXEFlowState {
-  XercesDOMParserFlowState() { encodeXercesDOMFlowState(this, _, _) }
+class XercesFlowState extends XXEFlowState {
+  XercesFlowState() { encodeXercesFlowState(this, _, _) }
 }

 /**
 * A flow state transformer for a call to
- * `AbstractDOMParser.setDisableDefaultEntityResolution`. Transforms the flow
+ * `AbstractDOMParser.setDisableDefaultEntityResolution` or
+ * `SAXParser.setDisableDefaultEntityResolution`. Transforms the flow
 * state through the qualifier according to the setting in the parameter.
 */
 class DisableDefaultEntityResolutionTranformer extends XXEFlowStateTranformer {
@@ -101,7 +110,10 @@ class DisableDefaultEntityResolutionTranformer extends XXEFlowStateTranformer {
  DisableDefaultEntityResolutionTranformer() {
    exists(Call call, Function f |
      call.getTarget() = f and
-      f.getDeclaringType() instanceof AbstractDOMParserClass and
+      (
+        f.getDeclaringType() instanceof AbstractDOMParserClass or
+        f.getDeclaringType() instanceof SAXParser
+      ) and
      f.hasName("setDisableDefaultEntityResolution") and
      this = call.getQualifier() and
      newValue = call.getArgument(0)
@@ -110,13 +122,13 @@ class DisableDefaultEntityResolutionTranformer extends XXEFlowStateTranformer {

  final override XXEFlowState transform(XXEFlowState flowstate) {
    exists(int createEntityReferenceNodes |
-      encodeXercesDOMFlowState(flowstate, _, createEntityReferenceNodes) and
+      encodeXercesFlowState(flowstate, _, createEntityReferenceNodes) and
      (
        newValue.getValue().toInt() = 1 and // true
-        encodeXercesDOMFlowState(result, 1, createEntityReferenceNodes)
+        encodeXercesFlowState(result, 1, createEntityReferenceNodes)
        or
        not newValue.getValue().toInt() = 1 and // false or unknown
-        encodeXercesDOMFlowState(result, 0, createEntityReferenceNodes)
+        encodeXercesFlowState(result, 0, createEntityReferenceNodes)
      )
    )
  }
@@ -142,27 +154,31 @@ class CreateEntityReferenceNodesTranformer extends XXEFlowStateTranformer {

  final override XXEFlowState transform(XXEFlowState flowstate) {
    exists(int disabledDefaultEntityResolution |
-      encodeXercesDOMFlowState(flowstate, disabledDefaultEntityResolution, _) and
+      encodeXercesFlowState(flowstate, disabledDefaultEntityResolution, _) and
      (
        newValue.getValue().toInt() = 1 and // true
-        encodeXercesDOMFlowState(result, disabledDefaultEntityResolution, 1)
+        encodeXercesFlowState(result, disabledDefaultEntityResolution, 1)
        or
        not newValue.getValue().toInt() = 1 and // false or unknown
-        encodeXercesDOMFlowState(result, disabledDefaultEntityResolution, 0)
+        encodeXercesFlowState(result, disabledDefaultEntityResolution, 0)
      )
    )
  }
 }

 /**
- * The `AbstractDOMParser.parse` method.
+ * The `AbstractDOMParser.parse` or `SAXParser.parse` method.
 */
 class ParseFunction extends Function {
-  ParseFunction() { this.getClassAndName("parse") instanceof AbstractDOMParserClass }
+  ParseFunction() {
+    this.getClassAndName("parse") instanceof AbstractDOMParserClass or
+    this.getClassAndName("parse") instanceof SAXParser
+  }
 }

 /**
- * The `createLSParser` function that returns a newly created `LSParser` object.
+ * The `createLSParser` function that returns a newly created `DOMLSParser`
+ * object.
 */
 class CreateLSParser extends Function {
  CreateLSParser() {
@@ -184,14 +200,23 @@ class XXEConfiguration extends DataFlow::Configuration {
      call.getStaticCallTarget() = any(XercesDOMParserClass c).getAConstructor() and
      node.asInstruction().(WriteSideEffectInstruction).getDestinationAddress() =
        call.getThisArgument() and
-      encodeXercesDOMFlowState(flowstate, 0, 1) // default configuration
+      encodeXercesFlowState(flowstate, 0, 1) // default configuration
    )
    or
    // source is the result of a call to `createLSParser`.
    exists(Call call |
      call.getTarget() instanceof CreateLSParser and
      call = node.asExpr() and
-      encodeXercesDOMFlowState(flowstate, 0, 1) // default configuration
+      encodeXercesFlowState(flowstate, 0, 1) // default configuration
+    )
+    or
+    // source is the write on `this` of a call to the `SAXParser`
+    // constructor.
+    exists(CallInstruction call |
+      node.asInstruction().(WriteSideEffectInstruction).getDestinationAddress() =
+        call.getThisArgument() and
+      call.getStaticCallTarget().(Constructor).getDeclaringType() instanceof SAXParser and
+      encodeXercesFlowState(flowstate, 0, 1) // default configuration
    )
  }

@@ -201,8 +226,8 @@ class XXEConfiguration extends DataFlow::Configuration {
      call.getTarget() instanceof ParseFunction and
      call.getQualifier() = node.asConvertedExpr()
    ) and
-    flowstate instanceof XercesDOMParserFlowState and
-    not encodeXercesDOMFlowState(flowstate, 1, 1) // safe configuration
+    flowstate instanceof XercesFlowState and
+    not encodeXercesFlowState(flowstate, 1, 1) // safe configuration
  }

  override predicate isAdditionalFlowStep(
--- a/cpp/ql/test/query-tests/Security/CWE/CWE-611/XXE.expected
+++ b/cpp/ql/test/query-tests/Security/CWE/CWE-611/XXE.expected
@@ -1,4 +1,7 @@
 edges
+| tests2.cpp:20:17:20:31 | SAXParser output argument | tests2.cpp:22:2:22:2 | p |
+| tests2.cpp:33:17:33:31 | SAXParser output argument | tests2.cpp:37:2:37:2 | p |
+| tests2.cpp:41:17:41:31 | SAXParser output argument | tests2.cpp:45:2:45:2 | p |
 | tests.cpp:33:23:33:43 | XercesDOMParser output argument | tests.cpp:35:2:35:2 | p |
 | tests.cpp:46:23:46:43 | XercesDOMParser output argument | tests.cpp:49:2:49:2 | p |
 | tests.cpp:53:19:53:19 | VariableAddress [post update] | tests.cpp:55:2:55:2 | p |
@@ -27,6 +30,12 @@ edges
 | tests.cpp:146:18:146:18 | q | tests.cpp:134:39:134:39 | p |
 | tests.cpp:150:19:150:32 | call to createLSParser | tests.cpp:152:2:152:2 | p |
 nodes
+| tests2.cpp:20:17:20:31 | SAXParser output argument | semmle.label | SAXParser output argument |
+| tests2.cpp:22:2:22:2 | p | semmle.label | p |
+| tests2.cpp:33:17:33:31 | SAXParser output argument | semmle.label | SAXParser output argument |
+| tests2.cpp:37:2:37:2 | p | semmle.label | p |
+| tests2.cpp:41:17:41:31 | SAXParser output argument | semmle.label | SAXParser output argument |
+| tests2.cpp:45:2:45:2 | p | semmle.label | p |
 | tests.cpp:33:23:33:43 | XercesDOMParser output argument | semmle.label | XercesDOMParser output argument |
 | tests.cpp:35:2:35:2 | p | semmle.label | p |
 | tests.cpp:46:23:46:43 | XercesDOMParser output argument | semmle.label | XercesDOMParser output argument |
@@ -66,6 +75,9 @@ nodes
 | tests.cpp:152:2:152:2 | p | semmle.label | p |
 subpaths
 #select
+| tests2.cpp:22:2:22:2 | p | tests2.cpp:20:17:20:31 | SAXParser output argument | tests2.cpp:22:2:22:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests2.cpp:20:17:20:31 | SAXParser output argument | XML parser |
+| tests2.cpp:37:2:37:2 | p | tests2.cpp:33:17:33:31 | SAXParser output argument | tests2.cpp:37:2:37:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests2.cpp:33:17:33:31 | SAXParser output argument | XML parser |
+| tests2.cpp:45:2:45:2 | p | tests2.cpp:41:17:41:31 | SAXParser output argument | tests2.cpp:45:2:45:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests2.cpp:41:17:41:31 | SAXParser output argument | XML parser |
 | tests.cpp:35:2:35:2 | p | tests.cpp:33:23:33:43 | XercesDOMParser output argument | tests.cpp:35:2:35:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests.cpp:33:23:33:43 | XercesDOMParser output argument | XML parser |
 | tests.cpp:49:2:49:2 | p | tests.cpp:46:23:46:43 | XercesDOMParser output argument | tests.cpp:49:2:49:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests.cpp:46:23:46:43 | XercesDOMParser output argument | XML parser |
 | tests.cpp:57:2:57:2 | p | tests.cpp:53:23:53:43 | XercesDOMParser output argument | tests.cpp:57:2:57:2 | p | This $@ is not configured to prevent an XML external entity (XXE) attack. | tests.cpp:53:23:53:43 | XercesDOMParser output argument | XML parser |
--- a/cpp/ql/test/query-tests/Security/CWE/CWE-611/tests2.cpp
+++ b/cpp/ql/test/query-tests/Security/CWE/CWE-611/tests2.cpp
@@ -19,7 +19,7 @@ public:
 void test2_1(InputSource &data) {
 	SAXParser *p = new SAXParser();

-	p->parse(data); // BAD (parser not correctly configured) [NOT DETECTED]
+	p->parse(data); // BAD (parser not correctly configured)
 }

 void test2_2(InputSource &data) {
@@ -34,7 +34,7 @@ void test2_3(InputSource &data) {
 	bool v = false;

 	p->setDisableDefaultEntityResolution(v);
-	p->parse(data); // BAD (parser not correctly configured) [NOT DETECTED]
+	p->parse(data); // BAD (parser not correctly configured)
 }

 void test2_4(InputSource &data) {
@@ -42,5 +42,5 @@ void test2_4(InputSource &data) {
 	bool v = true;

 	p->setDisableDefaultEntityResolution(v);
-	p->parse(data); // GOOD
+	p->parse(data); // GOOD [FALSE POSITIVE]
 }