CVE-2022-0396: DoS from specifically crafted TCP packets

[Everett B. Fulton]

CVE: CVE-2022-0396
Document version: 2.0
Posting date: 16 March 2022
Program impacted: BIND
Versions affected: BIND 9.16.11 -> 9.16.26, 9.17.0 -> 9.18.0 and versions
                     9.16.11-S1 -> 9.16.26-S1 of the BIND Supported Preview
                     Edition.
Severity: Medium
Exploitable: Remotely

Description:

    ISC recently discovered an issue in BIND that allows TCP connection 
slots
    to be consumed for an indefinite time frame via a specifically crafted
    TCP stream sent from a client. This issue is present in BIND 9.16.11 to
    9.16.26 (including S editions), and 9.18.0.

    This issue can only be triggered on BIND servers which have
    `keep-response-order` enabled, which is not the default configuration.
    The `keep-response-order` option is an ACL block; any hosts which are
    specified within it will be able to trigger this issue on affected
    versions.

Impact:

    Specifically crafted TCP streams can cause connections to BIND to remain
    in CLOSE_WAIT status for an indefinite period of time, even after the
    client has terminated the connection.

CVSS Score: 4.9

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:F/RL:O/RC:C

For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:F/RL:O/RC:C&version=3.1

Workarounds:

    To mitigate this issue in all affected versions of BIND, use the default
    setting of:

      keep-response-order { none; }.

Active exploits:

    We are not aware of any active exploits.

Solution:

    Upgrade to the patched release most closely related to your current
    version of BIND:

      9.16.27
      9.18.1

    BIND Supported Preview Edition is a special feature-preview branch of
    BIND provided to eligible ISC support customers.

      9.16.27-S1

Document revision history:

    1.0 Early Notification, 9 March 2022
    1.1 Grammatical edit to Description, 16 March 2022
    2.0 Public disclosure, 16 March 2022

Related documents:

See "CVE-2019-6477: TCP-pipelined queries can bypass tcp-clients limit" for
more information regarding CVE-2019-6477, in which ISC recommended setting
`keep-response-order` to `any` to work around a previous issue where BIND
was not respecting the TCP client limit:
https://kb.isc.org/docs/cve-2019-6477

See our BIND 9 Security Vulnerability Matrix for a complete listing of
security vulnerabilities and versions affected:
https://kb.isc.org/docs/aa-00913

Do you still have questions? Questions regarding this advisory should go
to security-officer at isc.org. To report a new issue, please encrypt your
message using security-officer at isc.org's PGP key which can be found here:
https://www.isc.org/pgpkey/. If you are unable to use encrypted email, you
may also report new issues at: https://www.isc.org/reportbug/.

Note:

ISC patches only currently supported versions. When possible we indicate
EOL versions affected. (For current information on which versions are
actively supported, please see https://www.isc.org/download/.)

ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be found
in the ISC Software Defect and Security Vulnerability Disclosure Policy at
https://kb.isc.org/docs/aa-00861

The Knowledgebase article https://kb.isc.org/docs/cve-2022-0396 is the
complete and official security advisory document.

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