Summary

• A Java deserialization vulnerability in Cisco Unity Express (CUE) could allow an unauthenticated, remote attacker to execute arbitrary shell commands with the privileges of the root user.

  The vulnerability is due to insecure deserialization of user-supplied content by the affected software. An attacker could exploit this vulnerability by sending a malicious serialized Java object to the listening Java Remote Method Invocation (RMI) service. A successful exploit could allow the attacker to execute arbitrary commands on the device with root privileges.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-cue

Affected Products

• Vulnerable Products

  This vulnerability affects all releases of Cisco Unity Express prior to release 9.0.6. Administrators can use one of the following methods to determine which version of software is running on the device:

  Cisco Unity Express - Administration Login Page

  On the Cisco Unity Express Administration login page, under the heading Cisco Unity Express - Administration, the Version field indicates the current version of software running on the device.

  Cisco Unity Express - Command Line Interface

  From the CUE CLI, enter the show software versions command. The following example shows a device that is running version 9.0.0:

  CUE# show software versions
  Cisco Unity Express Virtual version (9.0.0)
  Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2016 by Cisco Systems, Inc.

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

Workarounds

• Access Control List

  This vulnerability can be exploited over TCP port 1099. The CUE does not need this port to be open externally and may be blocked to protect against remote exploitation of this vulnerability. An administrator can configure an access control list that blocks all traffic with a destination port of TCP/1099 from reaching the CUE as shown in the following example:

  interface SM2/0
   ip unnumbered GigabitEthernet0/0
   ip access-group CSCvm02856_Mitigation in
   ip access-group CSCvm02856_Mitigation out
   service-module ip address 192.168.0.2 255.255.255.0
   !Application: CUE Running on SM
   service-module ip default-gateway 192.168.0.1
  !
  ip access-list extended CSCvm02856_Mitigation
   deny   tcp any host 192.168.0.2 eq 1099
   deny   tcp host 192.168.0.2 eq 1099 any
   permit any any
  

Fixed Software

• Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:
  https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

  Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.

  When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.

  In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

  Customers Without Service Contracts

  Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC:
  https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

  Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.

  Fixed Releases

  This vulnerability is fixed in Cisco Unity Express 9.0.6 and later releases. The software can be downloaded from the Software Center Cisco.com by navigating to Browse All > Unified Communications > Unified Communications Applications > Messaging > Unity Express > Unity Express Version 9.

  There are no current plans to release a fixed version of CUE 8.6. Customers on CUE 8.6 are recommended to implement the workaround or migrate to CUE 9.0.6. 

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank Joshua Graham of TSS for reporting this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-cue

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2018-November-07

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