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AUSCERT External Security Bulletin Redistribution
ESB-2018.3939
Cisco Adaptive Security Appliance Software Privilege
Escalation Vulnerability
21 December 2018
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Adaptive Security Appliance Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Increased Privileges -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2018-15465
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181219-asa-privesc
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Cisco Adaptive Security Appliance Software Privilege Escalation Vulnerability
High
Advisory ID: cisco-sa-20181219-asa-privesc
First Published: 2018 December 19 16:00 GMT
Version 1.0: Final
Workarounds: Yes
Cisco Bug IDs: CSCvm53531
CVE-2018-15465
CWE-285
CVSS Score: Base 8.1
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N/E:X/RL:X/RC:X
Summary
o A vulnerability in the authorization subsystem of Cisco Adaptive Security
Appliance (ASA) Software could allow an authenticated, but unprivileged
(levels 0 and 1), remote attacker to perform privileged actions by using
the web management interface.
The vulnerability is due to improper validation of user privileges when
using the web management interface. An attacker could exploit this
vulnerability by sending specific HTTP requests via HTTPS to an affected
device as an unprivileged user. An exploit could allow the attacker to
retrieve files (including the running configuration) from the device or to
upload and replace software images on the device.
Cisco has released software updates that address this vulnerability. There
are workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181219-asa-privesc
Affected Products
o Vulnerable Products
This vulnerability affects Cisco ASA Software that is running on any Cisco
product that has web management access enabled.
Determine Whether Web Management Access Is Configured
Administrators can use the show running-config http command to determine
whether web management access is enabled. The following example shows the
output of the command for a device that has the web management feature
enabled and that allows access to the web management feature from the
10.10.10.0/24 network via the Management interface:
ciscoasa# show running-config http
http server enable
http 10.10.10.0 255.255.255.0 Management
Note: The device is vulnerable to requests only when they are sent from an
IP address in the range configured in the http <remote_ip_address>
<remote_subnet_mask> <interface_name> command.
Determine the Cisco ASA Software Release
To determine which Cisco ASA Software release is running on a device,
administrators can log in to the device, use the show version command in
the CLI, and refer to the output of the command. The following example
shows the output of the command for a device that is running Cisco ASA
Software Release 9.4(4):
ciscoasa# show version | include Version
Cisco Adaptive Security Appliance Software Version 9.4(4)
Device Manager Version 7.4(1)
.
.
.
If a device is managed by using Cisco Adaptive Security Device Manager
(ASDM), administrators can also determine which release is running on a
device by referring to the release information in the table that appears in
the Cisco ASDM login window or the Device Dashboard tab of the Cisco ASDM
Home pane.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that Cisco Firepower Threat Defense (FTD) Software is
not affected by this vulnerability.
Details
o This vulnerability could allow an authenticated but unprivileged (levels 0
and 1) user to perform privileged actions when command authorization is
disabled on the Cisco ASA.
When command authorization is not enabled, the ASA distinguishes only
between unprivileged (levels 0 and 1) and privileged (levels 2 through 15)
users. Privileged (levels 2 through 15) users are expected to have full
administrative access to the ASA via the web management interface, even
without knowing the enable password. Command authorization is disabled on
the ASA by default.
The "AAA and the Local Database" chapter in the Cisco ASA Configuration
Guide provides further information.
Workarounds
o Enabling command authorization prevents exploitation of this vulnerability.
Notes
Enabling command authorization significantly changes the way that the Cisco
ASA interprets privilege levels and authorizes actions. Before enabling the
feature, administrators must clearly define which actions are allowed per
privilege level using the privilege command in global configuration mode.
Administrators should not enable command authorization using the aaa
authorization command command until they have defined these actions.
Administrators who use the Adaptive Security Device Manager (ASDM) to
manage the ASA are advised to enable command authorization by using the
ASDM because doing so will allow the ASDM to push predefined command sets
for different privilege levels to the ASA. Having these command sets in
place will ensure proper ASDM operation after command authorization is
enabled.
Further information about command authorization is in the "Management
Access" chapter of the "System Administration" section in Cisco ASA Series
General Operations CLI Configuration Guide and Cisco ASA Series General
Operations ASDM Configuration Guide.
Fixed Software
o 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
Customers should upgrade to an appropriate release as indicated in the
following table:
Cisco ASA Software Release First Fixed Release for This Vulnerability
Prior to 9.1^1 Migrate to 9.4.4.29
9.1^1 Migrate to 9.4.4.29
9.2^1 Migrate to 9.4.4.29
9.3^1 Migrate to 9.4.4.29
9.4 9.4.4.29
9.5^1 Migrate to 9.6.4.20
9.6 9.6.4.20
9.7^1 Migrate to 9.8.3.18
9.8 9.8.3.18
9.9 9.9.2.36
9.10 9.10.1.7
^1 Cisco ASA Software releases prior to Release 9.4 and Cisco ASA Software
Releases 9.5 and 9.7 have reached end-of-software maintenance. Customers
should migrate to a supported release.
Customers can download the software from the Software Center on Cisco.com
by clicking Browse all and navigating to Security > Firewalls > Adaptive
Security Appliances (ASA) > ASA 5500-X Series Firewalls, where there is a
list of Cisco ASA hardware platforms. Choose a platform, then choose
Software on Chassis > Adaptive Security Appliance (ASA) Software. Most of
these software releases are listed under Interim.
Note: For the fix to be effective, customers who have web management access
enabled must ensure that the AAA configuration is accurate and complete. In
particular, the aaa authentication http console {LOCAL | <aaa-server>}
command must be present. For further information, refer to the "About ASDM
Authentication" section of the Cisco ASA Configuration Guide.
Exploitation and Public Announcements
o 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
o Cisco would like to thank Ken Johnson of Tenable, Inc. for reporting this
vulnerability.
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy. This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
Subscribe to Cisco Security Notifications
o Subscribe
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181219-asa-privesc
Revision History
o +---------+-------------------------+---------+--------+------------------+
| Version | Description | Section | Status | Date |
+---------+-------------------------+---------+--------+------------------+
| 1.0 | Initial public release. | - | Final | 2018-December-19 |
+---------+-------------------------+---------+--------+------------------+
Legal Disclaimer
o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT
OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information
or contain factual errors. The information in this document is intended for
end users of Cisco products.
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