Codeql复现CVE-2018-11776学习笔记

本文主要是介绍Codeql复现CVE-2018-11776学习笔记，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

基本使用

1、首先下载struts2漏洞版本源码：
https://codeload.github.com/apache/struts/zip/refs/tags/STRUTS_2_3_20
2、构建codeql数据库（构建失败文末有解决办法）：

codeql database create ~/CodeQL/databases/struts2-2.3.20-database  --language="java"  --command="mvn clean install --file pom.xml" --source-root=~/CodeQL/struts-STRUTS_2_3_20/xwork-core

QL代码编写

source的建模

以S2-032 ( CVE-2016-3081 )、S2-033 ( CVE-2016-3687 ) 和S2-037 ( CVE-2016-4438 )为例，这三个漏洞都是与调用ognlUtil.getValue有关，比如下列代码：

String methodName = proxy.getMethod();    //<--- untrusted source, but where from?
LOG.debug("Executing action method = {}", methodName);
String timerKey = "invokeAction: " + proxy.getActionName();
try {UtilTimerStack.push(timerKey);Object methodResult;try {methodResult = ognlUtil.getValue(methodName + "()", getStack().getContext(), action); //<--- RCE

上面的代码中使用了proxy.getMethod()方法来获取不受信任的数据源，最终导致了调用ognlUtil.getValue造成了RCE，但除此之外还有各种方法，例如getActionName()和getNamespace()，所以可以编写如下QL代码，对这些不受信任的源进行建模：

class ActionProxyGetMethod extends Method {ActionProxyGetMethod() {getDeclaringType().getASupertype*().hasQualifiedName("com.opensymphony.xwork2", "ActionProxy") and(hasName("getMethod") orhasName("getNamespace") orhasName("getActionName"))}
}predicate isActionProxySource(DataFlow::Node source) {source.asExpr().(MethodAccess).getMethod() instanceof ActionProxyGetMethod
}

因为proxy是com.opensymphony.xwork2.ActionProxy类型，所以getDeclaringType().getASupertype*().hasQualifiedName(“com.opensymphony.xwork2”, “ActionProxy”)，其中*号代表递归

sink的建模

S2-032、S2-033和S2-037使用了 OgnlUtil::getValue()，然而在漏洞 S2-045（CVE-2017-5638）中，使用了 TextParseUtil::translateVariables()，所以推测一下OgnlUtil::compileAndExecute() 和 OgnlUtil::compileAndExecuteMethod() 也可能存在漏洞，所以对传入compileAndExecute、和compileAndExecute的sink进行建模：

predicate isOgnlSink(DataFlow::Node sink) {exists(MethodAccess ma | ma.getMethod().hasName("compileAndExecute") or ma.getMethod().hasName("compileAndExecuteMethod") | ma.getMethod().getDeclaringType().getName().matches("OgnlUtil") and sink.asExpr() = ma.getArgument(0))
}

MethodAccess表示方法访问，即当调用xxx.compileAndExecute或者xxx.compileAndExecuteMethod
ma.getMethod().getDeclaringType().getName().matches(“OgnlUtil”)表示该方法所在的类为OgnlUtil。

进行污点追踪

之前已经定义好了sink和source，所以直接将这两个套进去，这里重写了一个isAdditionalFlowStep，用来衔接一些没匹配到的参数。

class OgnlTaintTrackingCfg extends DataFlow::Configuration {OgnlTaintTrackingCfg() {this = "mapping"}override predicate isSource(DataFlow::Node source) {isActionProxySource(source)}override predicate isSink(DataFlow::Node sink) {isOgnlSink(sink)}override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {TaintTracking::localTaintStep(node1, node2) orexists(Field f, RefType t | node1.asExpr() = f.getAnAssignedValue() and node2.asExpr() = f.getAnAccess() andnode1.asExpr().getEnclosingCallable().getDeclaringType() = t andnode2.asExpr().getEnclosingCallable().getDeclaringType() = t)}
}from OgnlTaintTrackingCfg cfg, DataFlow::Node source, DataFlow::Node sink
where cfg.hasFlow(source, sink)
select source, sink

isAdditionalFlowStep用于衔接一些没匹配上的数据流，简单来说可能有如下情况，在调用bar()时没有提前调用foo()，导致数据流并不认为foo到bar是连通的所以默认DataFlow::Configuration是不包括这个流步骤的，因为也不能确定bar()中对this.field的访问总是被污染的，但是在漏洞挖掘中，包含这种形式的调用是非常有意义的。

public void foo(String taint) {this.field = taint;
}public void bar() {String x = this.field; //x is tainted because field is assigned to tainted value in `foo`
}

对isAdditionalFlowStep进行逐步分析：
TaintTracking::localTaintStep(node1, node2) 测试node1到node2的连通性。
Field 表示字段，RefType表示除了原始类型（int、float等）、null、数组的任何类型
f.getAnAssignedValue()表示获取被赋值给该字段的表达式。例如有一个字段int a，其中a = 10+20，那么表达式为10+20
f.getAnAccess()表示该字段的访问。例如int y = x；//访问字段x
node1.asExpr() = f.getAnAssignedValue() and node2.asExpr() = f.getAnAccess()这段连起来：表示有一个获取被赋值给字段的表达式node1，node2表达式对该字段进行了访问。
node1.asExpr().getEnclosingCallable().getDeclaringType() = t and node2.asExpr().getEnclosingCallable().getDeclaringType() = t表示node1和node2都是同一个类

最终代码

import java
import semmle.code.java.dataflow.DataFlow
import semmle.code.java.dataflow.TaintTrackingclass ActionProxyGetMethod extends Method{ActionProxyGetMethod(){getDeclaringType().getASupertype*().hasQualifiedName("com.opensymphony.xwork2", "ActionProxy") and(hasName("getMethod") orhasName("getActionName") orhasName("getNamespace"))}
}predicate isActionProxySource(DataFlow::Node source) {source.asExpr().(MethodAccess).getMethod() instanceof ActionProxyGetMethod}predicate isOgnlSink(DataFlow::Node sink) {exists(MethodAccess ma | ma.getMethod().hasName("compileAndExecute") or ma.getMethod().hasName("compileAndExecuteMethod") | ma.getMethod().getDeclaringType().getName().matches("OgnlUtil") and sink.asExpr() = ma.getArgument(0))
}class OgnlTaintTrackingCfg extends DataFlow::Configuration {OgnlTaintTrackingCfg() {this = "mapping"}override predicate isSource(DataFlow::Node source) {isActionProxySource(source)}override predicate isSink(DataFlow::Node sink) {isOgnlSink(sink)}override predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {TaintTracking::localTaintStep(node1, node2) orexists(Field f, RefType t | node1.asExpr() = f.getAnAssignedValue() and node2.asExpr() = f.getAnAccess() andnode1.asExpr().getEnclosingCallable().getDeclaringType() = t andnode2.asExpr().getEnclosingCallable().getDeclaringType() = t)}}from OgnlTaintTrackingCfg cfg, DataFlow::Node source, DataFlow::Node sinkwhere cfg.hasFlow(source, sink)select source, sink

坑点

1、构建数据库失败
～/CodeQL/struts-STRUTS_2_3_20/xwork-core/target/surefire-reports

-------------------------------------------------------------------------------
Test set: TestSuite
-------------------------------------------------------------------------------
Tests run: 741, Failures: 5, Errors: 0, Skipped: 0, Time elapsed: 13.404 sec <<< FAILURE!
testSetPropertiesDate(com.opensymphony.xwork2.ognl.OgnlUtilTest)  Time elapsed: 0.011 sec  <<< FAILURE!
junit.framework.AssertionFailedError: expected:<Fri Feb 12 00:00:00 CST 1982> but was:<null>at junit.framework.Assert.fail(Assert.java:47)at junit.framework.Assert.failNotEquals(Assert.java:283)at junit.framework.Assert.assertEquals(Assert.java:64)at junit.framework.Assert.assertEquals(Assert.java:71)at com.opensymphony.xwork2.ognl.OgnlUtilTest.testSetPropertiesDate(OgnlUtilTest.java:351)testRangeValidation(com.opensymphony.xwork2.validator.DateRangeValidatorTest)  Time elapsed: 0.028 sec  <<< FAILURE!
junit.framework.AssertionFailedError: Expected date range validation error message.at junit.framework.Assert.fail(Assert.java:47)at junit.framework.Assert.assertTrue(Assert.java:20)at junit.framework.Assert.assertNotNull(Assert.java:214)at com.opensymphony.xwork2.validator.DateRangeValidatorTest.testRangeValidation(DateRangeValidatorTest.java:60)testVisitorChildConversionValidation(com.opensymphony.xwork2.validator.VisitorFieldValidatorTest)  Time elapsed: 0.015 sec  <<< FAILURE!
junit.framework.AssertionFailedError: expected:<6> but was:<4>at junit.framework.Assert.fail(Assert.java:47)at junit.framework.Assert.failNotEquals(Assert.java:283)at junit.framework.Assert.assertEquals(Assert.java:64)at junit.framework.Assert.assertEquals(Assert.java:195)at junit.framework.Assert.assertEquals(Assert.java:201)at com.opensymphony.xwork2.validator.VisitorFieldValidatorTest.testVisitorChildConversionValidation(VisitorFieldValidatorTest.java:189)testVisitorChildValidation(com.opensymphony.xwork2.validator.VisitorFieldValidatorTest)  Time elapsed: 0.015 sec  <<< FAILURE!
junit.framework.AssertionFailedError: expected:<5> but was:<3>at junit.framework.Assert.fail(Assert.java:47)at junit.framework.Assert.failNotEquals(Assert.java:283)at junit.framework.Assert.assertEquals(Assert.java:64)at junit.framework.Assert.assertEquals(Assert.java:195)at junit.framework.Assert.assertEquals(Assert.java:201)at com.opensymphony.xwork2.validator.VisitorFieldValidatorTest.testVisitorChildValidation(VisitorFieldValidatorTest.java:167)testContextIsPropagated(com.opensymphony.xwork2.validator.VisitorFieldValidatorTest)  Time elapsed: 0.008 sec  <<< FAILURE!
junit.framework.AssertionFailedError: expected:<3> but was:<2>at junit.framework.Assert.fail(Assert.java:47)at junit.framework.Assert.failNotEquals(Assert.java:283)at junit.framework.Assert.assertEquals(Assert.java:64)at junit.framework.Assert.assertEquals(Assert.java:195)at junit.framework.Assert.assertEquals(Assert.java:201)at com.opensymphony.xwork2.validator.VisitorFieldValidatorTest.testContextIsPropagated(VisitorFieldValidatorTest.java:153)