Cisco Security Advisory
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AV:N/AC:L/Au:N/C:N/I:N/A:P/E:F/RL:U/RC:C
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A vulnerability in the Secure Shell Version 2 (SSHv2) protocol of Cisco Aironet 1800 Series Access Points could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high CPU utilization and an accumulation of SSHv2 connections.
The vulnerability is due to improper handling of incoming SSHv2 connections that do not complete properly. An attacker could exploit this vulnerability by sending a high number of crafted SSHv2 connections to an affected device. An exploit could allow the attacker to cause a DoS condition due to high CPU utilization and an accumulation of SSHv2 connections.
Cisco has not released software updates that address this vulnerability. Workarounds that mitigate this vulnerability are not available.
This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151113-aironet
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To assess whether there is high CPU utilization and an accumulation of SSHv2 connections on a device, use the show proc cpu command in the CLI, and refer to the values of the CPU fields and the number of root processes named -cisco shell. If there is a high number of root processes named -cisco shell there is an accumulation of SSHv2 connections, as indicated in the following example:
#show proc cpu Mem: 292804K used, 704332K free, 0K shrd, 0K buff, 41848K cached CPU: 96.1% usr 1.9% sys 0.0% nic 0.0% idle 0.0% io 0.0% irq 1.9% sirq Load average: 43.09 42.98 43.02 34/148 31388 PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND 11099 1 root R 4284 0.4 1 3.4 -cisco_shell . . .
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There are no workarounds that mitigate this vulnerability.
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When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to upgrade 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.
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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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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 2015-November-13
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