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             AUSCERT External Security Bulletin Redistribution

            Unbound: RCE vulnerability patched in IPSEC module
                             25 November 2019


        AusCERT Security Bulletin Summary

Product:           Unbound
Publisher:         NLNet Labs
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Execute Arbitrary Code/Commands -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-18934  

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

Vulnerability in IPSEC module

    Date:     2019-11-19
    CVE:      CVE-2019-18934
   Credit:    X41 D-Sec
  Affects:    Unbound 1.6.4 up to and including version 1.9.4
Not affected: Other versions
  Severity:   Critical
   Impact:    Shell code execution after a specially crafted answer
  Solution:   Download patched version of Unbound, or apply the patch manually

Due to unsanitized characters passed to the ipsecmod-hook shell command, it is
possible for Unbound to allow shell code execution from a specially crafted
IPSECKEY answer.

This issue can only be triggered when all of the below conditions are met:

  * unbound was compiled with --enable-ipsecmod support, and
  * ipsecmod is enabled and used in the configuration (either in the
    configuration file or using unbound-control), and
  * a domain is part of the ipsecmod-whitelist (if ipsecmod-whitelist is used),
  * unbound receives an A/AAAA query for a domain that has an A/AAAA record(s)
    and an IPSECKEY record(s) available.

The shell code execution can then happen if either the qname or the gateway
field of the IPSECKEY (when gateway type == 3) contain a specially crafted
domain name.

Unbound 1.9.5 contains a patch. If you cannot upgrade you can also apply the
patch manually. To do this, apply the patch on Unbound source directory with
patch -p1 < filename, then run make install to install Unbound.

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