Java安全之动态加载字节码( 四 )

解释以下为什么多了两个transform方法
这里是因为子类需要实现父类里面的抽象方法,同时因为父类是抽象类,可能没有将接口的方法全部实现,这时子类如果不是抽象的,那必须将其他接口方法都实现 。这里面 `transform(DOM document, DTMAxisIterator iterator,SerializationHandler handler)是父类里面的抽象方法所以要重写transform(DOM document, SerializationHandler[] handlers)是父类没有实现接口的方法所以要重写同样将其编译为class文件,然后base64编码最后就是写poc了,就新建一个TemplatesImpl对象,把属性设置进去然后执行newTransformer方法触发,主要是咱得先写一个利用反射给私有属性赋值的一个方法setFieldValue:
package org.gk0d;import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;import java.lang.reflect.Field;import java.util.Base64;public class a {    public static void setFieldValue(Object obj, String fieldName, Object Value) throws Exception {        Field field = obj.getClass().getDeclaredField(fieldName);        field.setAccessible(true);        field.set(obj, Value);    }    public static void main(String[] args) throws Exception {// source: bytecodes/HelloTemplateImpl.java        byte[] code = Base64.getDecoder().decode("yv66vgAAADQAIQoABgASCQATABQIABUKABYAFwcAGAcAGQEA" +                "CXRyYW5zZm9ybQEAcihMY29tL3N1bi9vcmcvYXBhY2hlL3hhbGFuL2ludGVybmFsL3hzbHRjL0RP" +                "TTtbTGNvbS9zdW4vb3JnL2FwYWNoZS94bWwvaW50ZXJuYWwvc2VyaWFsaXplci9TZXJpYWxpemF0" +                "aW9uSGFuZGxlcjspVgEABENvZGUBAA9MaW5lTnVtYmVyVGFibGUBAApFeGNlcHRpb25zBwAaAQCm" +                "KExjb20vc3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvRE9NO0xjb20vc3VuL29y" +                "Zy9hcGFjaGUveG1sL2ludGVybmFsL2R0bS9EVE1BeGlzSXRlcmF0b3I7TGNvbS9zdW4vb3JnL2Fw" +                "YWNoZS94bWwvaW50ZXJuYWwvc2VyaWFsaXplci9TZXJpYWxpemF0aW9uSGFuZGxlcjspVgEABjxp" +                "bml0PgEAAygpVgEAClNvdXJjZUZpbGUBABdIZWxsb1RlbXBsYXRlc0ltcGwuamF2YQwADgAPBwAb" +                "DAAcAB0BABNIZWxsbyBUZW1wbGF0ZXNJbXBsBwAeDAAfACABABJIZWxsb1RlbXBsYXRlc0ltcGwB" +                "AEBjb20vc3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvcnVudGltZS9BYnN0cmFj" +                "dFRyYW5zbGV0AQA5Y29tL3N1bi9vcmcvYXBhY2hlL3hhbGFuL2ludGVybmFsL3hzbHRjL1RyYW5z" +                "bGV0RXhjZXB0aW9uAQAQamF2YS9sYW5nL1N5c3RlbQEAA291dAEAFUxqYXZhL2lvL1ByaW50U3Ry" +                "ZWFtOwEAE2phdmEvaW8vUHJpbnRTdHJlYW0BAAdwcmludGxuAQAVKExqYXZhL2xhbmcvU3RyaW5n" +                "OylWACEABQAGAAAAAAADAAEABwAIAAIACQAAABkAAAADAAAAAbEAAAABAAoAAAAGAAEAAAAIAAsA" +                "AAAEAAEADAABAAcADQACAAkAAAAZAAAABAAAAAGxAAAAAQAKAAAABgABAAAACgALAAAABAABAAwA" +                "AQAOAA8AAQAJAAAALQACAAEAAAANKrcAAbIAAhIDtgAEsQAAAAEACgAAAA4AAwAAAA0ABAAOAAwA" +                "DwABABAAAAACABE=");        TemplatesImpl obj = new TemplatesImpl();        setFieldValue(obj, "_bytecodes", new byte[][]{code});        setFieldValue(obj, "_name", "HelloTemplatesImpl");        setFieldValue(obj, "_tfactory", new TransformerFactoryImpl());        obj.newTransformer();    }}

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