Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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A vulnerability in the implementation of Point-to-Point Tunneling Protocol (PPTP) functionality in Cisco Aironet 1810, 1830, and 1850 Series Access Points could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.
The vulnerability is due to insufficient validation of Generic Routing Encapsulation (GRE) frames that pass through the data plane of an affected access point. An attacker could exploit this vulnerability by initiating a PPTP connection to an affected access point from a device that is registered to the same wireless network as the access point and sending a malicious GRE frame through the data plane of the access point. A successful exploit could allow the attacker to cause the NSS core process on the affected access point to crash, which would cause the access point to reload and result in a DoS condition.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180502-ap-ptp
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Vulnerable Products
This vulnerability affects Cisco Aironet 1810, 1830, and 1850 Series Access Points that are running Cisco Mobility Express Software Release 8.4.100.0, 8.5.103.0, or 8.5.105.0 and are configured as a master, subordinate, or standalone access point.
Determining the Software Release
To determine which Cisco Mobility Express Software release is running on a Cisco Mobility Express controller and the associated access points, administrators can use the controller’s web interface or the access point’s CLI.
To use the controller's web interface, do the following:
- By using a browser, log in to the web interface.
- Choose Management > Software Update.
- Refer to the release number that appears at the top of the page.
To use the access point's CLI, log in to the access point via Telnet or SSH, issue the show version command, and then refer to the output of the command. The following example shows the output of the command for a Cisco Aironet 1852i Access Point that is running Cisco Mobility Express Software Release 8.3.111.0:
AP# show version cisco AIR-AP1852I-UXK9 ARMv7 Processor rev 0 (v71) with 997184/525160K bytes of memory. Processor board ID RFDP2BCR021 AP Running Image : 8.3.111.0 Primary Boot Image : 8.3.111.0 Backup Boot Image : 8.1.106.33 AP Image type : MOBILITY EXPRESS IMAGE AP Configuration : MOBILITY EXPRESS CAPABLE .
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.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 this vulnerability does not affect Cisco Aironet Access Points that are running Cisco Lightweight Access Point (AP) Software or Cisco IOS Software.
Cisco has also confirmed that this vulnerability does not affect the following Cisco products:
- Aironet 1560 Series Access Points
- Aironet 2800 Series Access Points
- Aironet 3800 Series Access Points
- Wireless LAN Controllers, any model
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There are no workarounds that address this vulnerability.
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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.htmlAdditionally, 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 ContractsCustomers 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 Technical Assistance Center (TAC):
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.htmlCustomers 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 table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
- cisco-sa-20180502-aironet-ssh: Cisco Aironet 1800, 2800, and 3800 Series Access Points Secure Shell Privilege Escalation Vulnerability
- cisco-sa-20180502-ap-ptp: Cisco Aironet 1810, 1830, and 1850 Series Access Points Point-to-Point Tunneling Protocol Denial of Service Vulnerability
- cisco-sa-20180502-wlc-ip: Cisco Wireless LAN Controller IP Fragment Reassembly Denial of Service Vulnerability
- cisco-sa-20180502-wlc-mfdos: Cisco Wireless LAN Controller 802.11 Management Frame Denial of Service Vulnerability
In the following table, the left column lists major releases of Cisco software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in this collection of advisories and which release includes fixes for those vulnerabilities.
Cisco Mobility Express Software Major Release First Fixed Release for This Vulnerability First Fixed Release for All Vulnerabilities Described in the Collection of Advisories Prior to 8.0 Not vulnerable Not vulnerable 8.0 Not vulnerable Not vulnerable 8.1 Not vulnerable Not vulnerable 8.2 Not vulnerable 8.5.120.0 8.3 Not vulnerable 8.5.120.0 8.4 8.5.110.0 8.5.120.0 8.5 8.5.110.0 8.5.120.0 8.6 Not vulnerable Not vulnerable 8.7 Not vulnerable Not vulnerable
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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.
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Cisco would like to thank Simon Lockhart of CableCom Networking for reporting this vulnerability.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2018-May-02
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