Search News Articles

Cisco IOS and IOS XE Software Cluster Management Protocol Remote Code Execution Vulnerability

Note: this is a reprint of March 17, 2017, Cisco announcement. The original announcement can be found here.

Advisory ID: cisco-sa-20170317-cmp                                  CVE-2017-3881

First Published: 2017 March 17 16:00 GMT

Version 1.0: Final

Workarounds: No workarounds available

Cisco Bug IDs: CSCvd48893

CVSS Score: Base 9.8, Temporal 9.8

Summary  

A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges.

The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors:
  • The failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device, and 
  • The incorrect processing of malformed CMP-specific Telnet options.

An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device.

Cisco will release 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-20170317-cmp


Affected Products 

Vulnerable Products 

This vulnerability affects the following Cisco devices when running a vulnerable Cisco IOS software release and configured to accept incoming Telnet connections:   

  •  Cisco Catalyst 2350-48TD-S Switch 
  •  Cisco Catalyst 2350-48TD-SD Switch 
  •  Cisco Catalyst 2360-48TD-S Switch 
  •  Cisco Catalyst 2918-24TC-C Switch 
  •  Cisco Catalyst 2918-24TT-C Switch 
  •  Cisco Catalyst 2918-48TC-C Switch 
  •  Cisco Catalyst 2918-48TT-C Switch 
  •  Cisco Catalyst 2928-24TC-C Switch 
  •  Cisco Catalyst 2960-24-S Switch 
  •  Cisco Catalyst 2960-24LC-S Switch 
  •  Cisco Catalyst 2960-24LT-L Switch 
  •  Cisco Catalyst 2960-24PC-L Switch 
  •  Cisco Catalyst 2960-24PC-S Switch 
  •  Cisco Catalyst 2960-24TC-L Switch 
  •  Cisco Catalyst 2960-24TC-S Switch 
  •  Cisco Catalyst 2960-24TT-L Switch 
  •  Cisco Catalyst 2960-48PST-L Switch 
  •  Cisco Catalyst 2960-48PST-S Switch 
  •  Cisco Catalyst 2960-48TC-L Switch 
  •  Cisco Catalyst 2960-48TC-S Switch 
  •  Cisco Catalyst 2960-48TT-L Switch 
  •  Cisco Catalyst 2960-48TT-S Switch 
  •  Cisco Catalyst 2960-8TC-L Compact Switch 
  •  Cisco Catalyst 2960-8TC-S Compact Switch 
  •  Cisco Catalyst 2960-Plus 24LC-L Switch 
  •  Cisco Catalyst 2960-Plus 24LC-S Switch 
  •  Cisco Catalyst 2960-Plus 24PC-L Switch 
  •  Cisco Catalyst 2960-Plus 24PC-S Switch 
  •  Cisco Catalyst 2960-Plus 24TC-L Switch 
  •  Cisco Catalyst 2960-Plus 24TC-S Switch 
  •  Cisco Catalyst 2960-Plus 48PST-L Switch 
  •  Cisco Catalyst 2960-Plus 48PST-S Switch 
  •  Cisco Catalyst 2960-Plus 48TC-L Switch 
  •  Cisco Catalyst 2960-Plus 48TC-S Switch 
  •  Cisco Catalyst 2960C-12PC-L Switch 
  •  Cisco Catalyst 2960C-8PC-L Switch 
  •  Cisco Catalyst 2960C-8TC-L Switch 
  •  Cisco Catalyst 2960C-8TC-S Switch 
  •  Cisco Catalyst 2960CG-8TC-L Compact Switch 
  •  Cisco Catalyst 2960CPD-8PT-L Switch 
  •  Cisco Catalyst 2960CPD-8TT-L Switch 
  •  Cisco Catalyst 2960CX-8PC-L Switch 
  •  Cisco Catalyst 2960CX-8TC-L Switch 
  •  Cisco Catalyst 2960G-24TC-L Switch 
  •  Cisco Catalyst 2960G-48TC-L Switch 
  •  Cisco Catalyst 2960G-8TC-L Compact Switch 
  •  Cisco Catalyst 2960L-16PS-LL Switch 
  •  Cisco Catalyst 2960L-16TS-LL Switch 
  •  Cisco Catalyst 2960L-24PS-LL Switch 
  •  Cisco Catalyst 2960L-24TS-LL Switch 
  •  Cisco Catalyst 2960L-48PS-LL Switch 
  •  Cisco Catalyst 2960L-48TS-LL Switch 
  •  Cisco Catalyst 2960L-8PS-LL Switch 
  •  Cisco Catalyst 2960L-8TS-LL Switch 
  •  Cisco Catalyst 2960PD-8TT-L Compact Switch 
  •  Cisco Catalyst 2960S-24PD-L Switch 
  •  Cisco Catalyst 2960S-24PS-L Switch 
  •  Cisco Catalyst 2960S-24TD-L Switch 
  •  Cisco Catalyst 2960S-24TS-L Switch 
  •  Cisco Catalyst 2960S-24TS-S Switch 
  •  Cisco Catalyst 2960S-48FPD-L Switch 
  •  Cisco Catalyst 2960S-48FPS-L Switch 
  •  Cisco Catalyst 2960S-48LPD-L Switch 
  •  Cisco Catalyst 2960S-48LPS-L Switch 
  •  Cisco Catalyst 2960S-48TD-L Switch 
  •  Cisco Catalyst 2960S-48TS-L Switch 
  •  Cisco Catalyst 2960S-48TS-S Switch 
  •  Cisco Catalyst 2960S-F24PS-L Switch 
  •  Cisco Catalyst 2960S-F24TS-L Switch 
  •  Cisco Catalyst 2960S-F24TS-S Switch 
  •  Cisco Catalyst 2960S-F48FPS-L Switch 
  •  Cisco Catalyst 2960S-F48LPS-L Switch 
  •  Cisco Catalyst 2960S-F48TS-L Switch 
  •  Cisco Catalyst 2960S-F48TS-S Switch 
  •  Cisco Catalyst 2960X-24PD-L Switch 
  •  Cisco Catalyst 2960X-24PS-L Switch 
  •  Cisco Catalyst 2960X-24PSQ-L Cool Switch 
  •  Cisco Catalyst 2960X-24TD-L Switch 
  •  Cisco Catalyst 2960X-24TS-L Switch 
  •  Cisco Catalyst 2960X-24TS-LL Switch 
  •  Cisco Catalyst 2960X-48FPD-L Switch 
  •  Cisco Catalyst 2960X-48FPS-L Switch 
  •  Cisco Catalyst 2960X-48LPD-L Switch 
  •  Cisco Catalyst 2960X-48LPS-L Switch 
  •  Cisco Catalyst 2960X-48TD-L Switch 
  •  Cisco Catalyst 2960X-48TS-L Switch 
  •  Cisco Catalyst 2960X-48TS-LL Switch 
  •  Cisco Catalyst 2960XR-24PD-I Switch 
  •  Cisco Catalyst 2960XR-24PD-L Switch 
  •  Cisco Catalyst 2960XR-24PS-I Switch 
  •  Cisco Catalyst 2960XR-24PS-L Switch 
  •  Cisco Catalyst 2960XR-24TD-I Switch 
  •  Cisco Catalyst 2960XR-24TD-L Switch 
  •  Cisco Catalyst 2960XR-24TS-I Switch 
  •  Cisco Catalyst 2960XR-24TS-L Switch 
  •  Cisco Catalyst 2960XR-48FPD-I Switch 
  •  Cisco Catalyst 2960XR-48FPD-L Switch 
  •  Cisco Catalyst 2960XR-48FPS-I Switch 
  •  Cisco Catalyst 2960XR-48FPS-L Switch 
  •  Cisco Catalyst 2960XR-48LPD-I Switch 
  •  Cisco Catalyst 2960XR-48LPD-L Switch 
  •  Cisco Catalyst 2960XR-48LPS-I Switch 
  •  Cisco Catalyst 2960XR-48LPS-L Switch 
  •  Cisco Catalyst 2960XR-48TD-I Switch 
  •  Cisco Catalyst 2960XR-48TD-L Switch 
  •  Cisco Catalyst 2960XR-48TS-I Switch 
  •  Cisco Catalyst 2960XR-48TS-L Switch 
  •  Cisco Catalyst 2970G-24T Switch 
  •  Cisco Catalyst 2970G-24TS Switch 
  •  Cisco Catalyst 2975 Switch 
  •  Cisco Catalyst 3550 12G Switch 
  •  Cisco Catalyst 3550 12T Switch 
  •  Cisco Catalyst 3550 24 DC SMI Switch 
  •  Cisco Catalyst 3550 24 EMI Switch 
  •  Cisco Catalyst 3550 24 FX SMI Switch 
  •  Cisco Catalyst 3550 24 PWR Switch 
  •  Cisco Catalyst 3550 24 SMI Switch 
  •  Cisco Catalyst 3550 48 EMI Switch 
  •  Cisco Catalyst 3550 48 SMI Switch 
  •  Cisco Catalyst 3560-12PC-S Compact Switch 
  •  Cisco Catalyst 3560-24PS Switch 
  •  Cisco Catalyst 3560-24TS Switch 
  •  Cisco Catalyst 3560-48PS Switch 
  •  Cisco Catalyst 3560-48TS Switch 
  •  Cisco Catalyst 3560-8PC Compact Switch 
  •  Cisco Catalyst 3560C-12PC-S Switch 
  •  Cisco Catalyst 3560C-8PC-S Switch 
  •  Cisco Catalyst 3560CG-8PC-S Compact Switch 
  •  Cisco Catalyst 3560CG-8TC-S Compact Switch 
  •  Cisco Catalyst 3560CPD-8PT-S Compact Switch 
  •  Cisco Catalyst 3560CX-12PC-S Switch 
  •  Cisco Catalyst 3560CX-12PD-S Switch 
  •  Cisco Catalyst 3560CX-12TC-S Switch 
  •  Cisco Catalyst 3560CX-8PC-S Switch 
  •  Cisco Catalyst 3560CX-8PT-S Switch 
  •  Cisco Catalyst 3560CX-8TC-S Switch 
  •  Cisco Catalyst 3560CX-8XPD-S Switch 
  •  Cisco Catalyst 3560E-12D-E Switch 
  •  Cisco Catalyst 3560E-12D-S Switch 
  •  Cisco Catalyst 3560E-12SD-E Switch 
  •  Cisco Catalyst 3560E-12SD-S Switch 
  •  Cisco Catalyst 3560E-24PD-E Switch 
  •  Cisco Catalyst 3560E-24PD-S Switch 
  •  Cisco Catalyst 3560E-24TD-E Switch 
  •  Cisco Catalyst 3560E-24TD-S Switch 
  •  Cisco Catalyst 3560E-48PD-E Switch 
  •  Cisco Catalyst 3560E-48PD-EF Switch 
  • Cisco Catalyst 3560E-48PD-S Switch 
  •  Cisco Catalyst 3560E-48PD-SF Switch 
  •  Cisco Catalyst 3560E-48TD-E Switch 
  •  Cisco Catalyst 3560E-48TD-S Switch 
  •  Cisco Catalyst 3560G-24PS Switch 
  •  Cisco Catalyst 3560G-24TS Switch 
  •  Cisco Catalyst 3560G-48PS Switch 
  •  Cisco Catalyst 3560G-48TS Switch 
  •  Cisco Catalyst 3560V2-24DC Switch 
  •  Cisco Catalyst 3560V2-24PS Switch 
  •  Cisco Catalyst 3560V2-24TS Switch 
  •  Cisco Catalyst 3560V2-48PS Switch 
  •  Cisco Catalyst 3560V2-48TS Switch 
  •  Cisco Catalyst 3560X-24P-E Switch 
  •  Cisco Catalyst 3560X-24P-L Switch 
  •  Cisco Catalyst 3560X-24P-S Switch 
  •  Cisco Catalyst 3560X-24T-E Switch 
  •  Cisco Catalyst 3560X-24T-L Switch 
  •  Cisco Catalyst 3560X-24T-S Switch 
  •  Cisco Catalyst 3560X-24U-E Switch 
  •  Cisco Catalyst 3560X-24U-L Switch 
  •  Cisco Catalyst 3560X-24U-S Switch 
  •  Cisco Catalyst 3560X-48P-E Switch 
  •  Cisco Catalyst 3560X-48P-L Switch 
  •  Cisco Catalyst 3560X-48P-S Switch 
  •  Cisco Catalyst 3560X-48PF-E Switch 
  •  Cisco Catalyst 3560X-48PF-L Switch 
  •  Cisco Catalyst 3560X-48PF-S Switch 
  •  Cisco Catalyst 3560X-48T-E Switch 
  •  Cisco Catalyst 3560X-48T-L Switch 
  •  Cisco Catalyst 3560X-48T-S Switch 
  •  Cisco Catalyst 3560X-48U-E Switch 
  •  Cisco Catalyst 3560X-48U-L Switch 
  •  Cisco Catalyst 3560X-48U-S Switch 
  •  Cisco Catalyst 3750 Metro 24-AC Switch 
  •  Cisco Catalyst 3750 Metro 24-DC Switch 
  •  Cisco Catalyst 3750-24FS Switch 
  •  Cisco Catalyst 3750-24PS Switch 
  •  Cisco Catalyst 3750-24TS Switch 
  •  Cisco Catalyst 3750-48PS Switch 
  •  Cisco Catalyst 3750-48TS Switch 
  •  Cisco Catalyst 3750E-24PD-E Switch 
  •  Cisco Catalyst 3750E-24PD-S Switch 
  •  Cisco Catalyst 3750E-24TD-E Switch 
  •  Cisco Catalyst 3750E-24TD-S Switch 
  •  Cisco Catalyst 3750E-48PD-E Switch 
  •  Cisco Catalyst 3750E-48PD-EF Switch 
  •  Cisco Catalyst 3750E-48PD-S Switch 
  •  Cisco Catalyst 3750E-48PD-SF Switch 
  •  Cisco Catalyst 3750E-48TD-E Switch 
  •  Cisco Catalyst 3750E-48TD-S Switch 
  •  Cisco Catalyst 3750G-12S Switch 
  •  Cisco Catalyst 3750G-12S-SD Switch 
  •  Cisco Catalyst 3750G-16TD Switch 
  •  Cisco Catalyst 3750G-24PS Switch 
  •  Cisco Catalyst 3750G-24T Switch 
  •  Cisco Catalyst 3750G-24TS Switch 
  •  Cisco Catalyst 3750G-24TS-1U Switch 
  •  Cisco Catalyst 3750G-48PS Switch 
  •  Cisco Catalyst 3750G-48TS Switch 
  •  Cisco Catalyst 3750V2-24FS Switch 
  •  Cisco Catalyst 3750V2-24PS Switch 
  •  Cisco Catalyst 3750V2-24TS Switch 
  •  Cisco Catalyst 3750V2-48PS Switch 
  •  Cisco Catalyst 3750V2-48TS Switch 
  •  Cisco Catalyst 3750X-12S-E Switch 
  •  Cisco Catalyst 3750X-12S-S Switch 
  •  Cisco Catalyst 3750X-24P-E Switch 
  •  Cisco Catalyst 3750X-24P-L Switch 
  •  Cisco Catalyst 3750X-24P-S Switch 
  •  Cisco Catalyst 3750X-24S-E Switch 
  •  Cisco Catalyst 3750X-24S-S Switch 
  •  Cisco Catalyst 3750X-24T-E Switch 
  •  Cisco Catalyst 3750X-24T-L Switch 
  •  Cisco Catalyst 3750X-24T-S Switch 
  •  Cisco Catalyst 3750X-24U-E Switch 
  •  Cisco Catalyst 3750X-24U-L Switch 
  •  Cisco Catalyst 3750X-24U-S Switch 
  •  Cisco Catalyst 3750X-48P-E Switch 
  •  Cisco Catalyst 3750X-48P-L Switch 
  •  Cisco Catalyst 3750X-48P-S Switch 
  •  Cisco Catalyst 3750X-48PF-E Switch 
  •  Cisco Catalyst 3750X-48PF-L Switch 
  •  Cisco Catalyst 3750X-48PF-S Switch 
  •  Cisco Catalyst 3750X-48T-E Switch 
  •  Cisco Catalyst 3750X-48T-L Switch 
  •  Cisco Catalyst 3750X-48T-S Switch 
  •  Cisco Catalyst 3750X-48U-E Switch 
  •  Cisco Catalyst 3750X-48U-L Switch 
  •  Cisco Catalyst 3750X-48U-S Switch 
  •  Cisco Catalyst 4000 Supervisor Engine I 
  •  Cisco Catalyst 4000/4500 Supervisor Engine IV 
  •  Cisco Catalyst 4000/4500 Supervisor Engine V 
  •  Cisco Catalyst 4500 Series Supervisor Engine II-Plus 
  •  Cisco Catalyst 4500 Series Supervisor Engine II-Plus-TS 
  •  Cisco Catalyst 4500 Series Supervisor Engine V-10GE 
  •  Cisco Catalyst 4500 Series Supervisor II-Plus-10GE 
  •  Cisco Catalyst 4500 Supervisor Engine 6-E 
  •  Cisco Catalyst 4500 Supervisor Engine 6L-E 
  •  Cisco Catalyst 4900M Switch 
  •  Cisco Catalyst 4928 10 Gigabit Ethernet Switch 
  •  Cisco Catalyst 4948 10 Gigabit Ethernet Switch 
  •  Cisco Catalyst 4948 Switch 
  •  Cisco Catalyst 4948E Ethernet Switch 
  •  Cisco Catalyst 4948E-F Ethernet Switch 
  •  Cisco Catalyst Blade Switch 3020 for HP 
  •  Cisco Catalyst Blade Switch 3030 for Dell 
  •  Cisco Catalyst Blade Switch 3032 for Dell M1000E 
  •  Cisco Catalyst Blade Switch 3040 for FSC 
  •  Cisco Catalyst Blade Switch 3120 for HP 
  •  Cisco Catalyst Blade Switch 3120X for HP 
  •  Cisco Catalyst Blade Switch 3130 for Dell M1000E 
  •  Cisco Catalyst C2928-24LT-C Switch 
  •  Cisco Catalyst C2928-48TC-C Switch 
  •  Cisco Catalyst Switch Module 3012 for IBM BladeCenter 
  •  Cisco Catalyst Switch Module 3110 for IBM BladeCenter 
  •  Cisco Catalyst Switch Module 3110X for IBM BladeCenter 
  •  Cisco Embedded Service 2020 24TC CON B Switch 
  •  Cisco Embedded Service 2020 24TC CON Switch 
  •  Cisco Embedded Service 2020 24TC NCP B Switch 
  •  Cisco Embedded Service 2020 24TC NCP Switch 
  •  Cisco Embedded Service 2020 CON B Switch 
  •  Cisco Embedded Service 2020 CON Switch 
  •  Cisco Embedded Service 2020 NCP B Switch 
  •  Cisco Embedded Service 2020 NCP Switch 
  •  Cisco Enhanced Layer 2 EtherSwitch Service Module 
  •  Cisco Enhanced Layer 2/3 EtherSwitch Service Module 
  •  Cisco Gigabit Ethernet Switch Module (CGESM) for HP 
  •  Cisco IE 2000-16PTC-G Industrial Ethernet Switch 
  •  Cisco IE 2000-16T67 Industrial Ethernet Switch 
  •  Cisco IE 2000-16T67P Industrial Ethernet Switch 
  •  Cisco IE 2000-16TC Industrial Ethernet Switch 
  •  Cisco IE 2000-16TC-G Industrial Ethernet Switch 
  •  Cisco IE 2000-16TC-G-E Industrial Ethernet Switch 
  •  Cisco IE 2000-16TC-G-N Industrial Ethernet Switch 
  •  Cisco IE 2000-16TC-G-X Industrial Ethernet Switch 
  •  Cisco IE 2000-24T67 Industrial Ethernet Switch 
  •  Cisco IE 2000-4S-TS-G Industrial Ethernet Switch 
  •  Cisco IE 2000-4T Industrial Ethernet Switch 
  •  Cisco IE 2000-4T-G Industrial Ethernet Switch 
  •  Cisco IE 2000-4TS Industrial Ethernet Switch 
  •  Cisco IE 2000-4TS-G Industrial Ethernet Switch 
  •  Cisco IE 2000-8T67 Industrial Ethernet Switch 
  •  Cisco IE 2000-8T67P Industrial Ethernet Switch 
  •  Cisco IE 2000-8TC Industrial Ethernet Switch 
  •  Cisco IE 2000-8TC-G Industrial Ethernet Switch 
  •  Cisco IE 2000-8TC-G-E Industrial Ethernet Switch 
  •  Cisco IE 2000-8TC-G-N Industrial Ethernet Switch 
  •  Cisco IE 3000-4TC Industrial Ethernet Switch 
  •  Cisco IE 3000-8TC Industrial Ethernet Switch 
  •  Cisco IE-3010-16S-8PC Industrial Ethernet Switch 
  •  Cisco IE-3010-24TC Industrial Ethernet Switch 
  •  Cisco IE-4000-16GT4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-16T4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-4GC4GP4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-4GS8GP4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-4S8P4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-4T4P4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-4TC4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-8GS4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-8GT4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-8GT8GP4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-8S4G-E Industrial Ethernet Switch 
  •  Cisco IE-4000-8T4G-E Industrial Ethernet Switch 
  •  Cisco IE-4010-16S12P Industrial Ethernet Switch
  •  Cisco IE-4010-4S24P Industrial Ethernet Switch 
  •  Cisco IE-5000-12S12P-10G Industrial Ethernet Switch 
  •  Cisco IE-5000-16S12P Industrial Ethernet Switch 
  •  Cisco ME 4924-10GE Switch Cisco RF Gateway 10 
  •  Cisco SM-X Layer 2/3 EtherSwitch Service Module  
Note: Checking for the presence of the CMP subsystem is only required on devices running Cisco IOS XE Software, not Cisco IOS Software. Checking if the device is configured to accept Telnet connections is required for devices running either Cisco IOS or Cisco IOS XE Software.

Cisco devices running a vulnerable Cisco IOS XE release are affected by this vulnerability when the following conditions are met:
  • The CMP subsystem is present on the Cisco IOS XE software image running on the device, and 
  • The device is configured to accept incoming Telnet connections.
In order to determine if the CMP subsystem is present on the running software image, execute the command show subsys class protocol | include ^cmp from a privileged CLI prompt on the device.

The following example shows the output of the command show subsys class protocol | include ^cmp when the CMP subsystem is present on the software image running on the device:  

Switch#show subsys class protocol | include ^cmp 
cmp Protocol 1.000.001 
Switch#

The following example shows the output of the command show subsys class protocol | include ^cmp when the CMP subsystem is not present on the software image running on the device: 

Switch#show subsys class protocol | include ^cmp 
Switch#

In order to determine if the device is configured to accept incoming Telnet connections, execute the command show running-config | include ^line vty|transport input from a privileged CLI prompt. The command output may indicate one of multiple possible configurations, such as the following:

    • The absence of a transport input configuration line after the line vty configuration line indicates the device is using the default set of protocols for incoming connections through a virtual terminal (VTY). The default set of protocols includes the Telnet protocol; hence, this device will accept Telnet connections on all VTYs. This is a vulnerable configuration.

Switch#show running-config | include ^line vty|transport input 

line vty 0 4 

line vty 5 15 

Switch# 

      • The device has been explicitly configured to only accept the Secure Shell (SSH) protocol for incoming connections to a subset of the available VTYs, but VTYs numbered 6 to 15 are still using the default set of protocols. Hence, this device will accept Telnet connections to those VTYs. This is a vulnerable configuration.

Switch#show running-config | include ^line vty|transport input 

line vty 0 4 

transport input ssh 

line vty 5 

transport input ssh 

line vty 6 15 

Switch#

      • All available transport protocols have been enabled for incoming connections to all VTYs. Enabling all protocols also enables the Telnet protocol, and will allow Telnet connections to the device. This is a vulnerable configuration.

Switch#show running-config | include ^line vty|transport input 

line vty 0 4 

transport input all 

line vty 5 15 

transport input all 

Switch#

  • The SSH protocol is the only protocol enabled for incoming connections on all VTYs. No Telnet connections are possible to any VTY on the device while using this configuration. This configuration is not vulnerable.

Switch#show running-config | include ^line vty|transport input 
line vty 0 4 
transport input ssh 
line vty 5 15 
transport input ssh 
Switch#

  • Both the Telnet and the SSH protocols have been explicitly enabled as allowed protocols for incoming connections on all VTYs. Telnet connections to the device will be successful under this configuration. This is a vulnerable configuration.
Switch#show running-config | include ^line vty|transport input 
line vty 0 4 
transport input telnet ssh 
line vty 5 15 
transport input telnet ssh

Determining the Cisco IOS Software Release 

To determine which Cisco IOS Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS Software, the system banner displays text similar to Cisco Internetwork Operating System Software or Cisco IOS Software. The banner also displays the installed image name in parentheses, followed by the Cisco IOS Software release number and release name. Some Cisco devices do not support the show version command or may provide different output.

The following example identifies a Cisco product that is running Cisco IOS Software Release 15.5(2)T1 with an installed image name of C2951-UNIVERSALK9-M:

Router> show version  

Cisco IOS Software, C2951 Software (C2951-UNIVERSALK9-M), 

Version 15.5(2)T1, RELEASE SOFTWARE (fc1) 

Technical Support: http://www.cisco.com/techsupport 

Copyright (c) 1986-2015 by Cisco Systems, Inc. 

Compiled Mon 22-Jun-15 09:32 by prod_rel_team

For information about the naming and numbering conventions for Cisco IOS Software releases, see White Paper: Cisco IOS and NX-OS Software Reference Guide.

Determining the Cisco IOS XE Software Release  

To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS XE Software or similar text.

The following example shows the output of the show version command on a device that is running Cisco IOS XE Software Release 3.16.1aS:

Router> show version  
Cisco IOS XE Software, Version 03.16.01a.S - Extended Support Release 
Cisco IOS Software, ASR1000 Software (PPC_LINUX_IOSD-ADVENTERPRISEK9-M), 
Version 15.5(3)S1a, RELEASE SOFTWARE (fc1) 
Technical Support: http://www.cisco.com/techsupport 
Copyright (c) 1986-2015 by Cisco Systems, Inc. 
Compiled Wed 04-Nov-15 17:40 by mcpre

For information about the naming and numbering conventions for Cisco IOS XE Software releases, see White Paper: Cisco IOS and NX-OS Software Reference Guide.

Products Confirmed Not Vulnerable    


No other Cisco products are currently known to be affected by this vulnerability. 

Cisco devices running a vulnerable Cisco IOS Software release but not listed under the "Vulnerable Products" section of this advisory are not affected by this vulnerability. 

Cisco devices running a vulnerable Cisco IOS XE Software release but not including the CMP protocol subsystem are not affected by this vulnerability.

Details  

A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges.

The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors:
  • The failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device, and 
  • The incorrect processing of malformed CMP-specific Telnet options.
An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device.

CMP-specific Telnet options are processed by default, even if no cluster configuration commands are present on the device configuration. 

This vulnerability can be exploited during Telnet session negotiation over either IPv4 or IPv6. This vulnerability can only be exploited through a Telnet session established to the device—sending the malformed options on Telnet sessions through the device will not trigger the vulnerability.

Indicators of Compromise 

Cisco IPS Signature 7880-0 and Snort SIDs 41909 and 41910 can detect attempts to exploit this vulnerability.

Workarounds   

There are no workarounds that address this vulnerability. 

Disabling the Telnet protocol as an allowed protocol for incoming connections would eliminate the exploit vector. Disabling Telnet and using SSH is recommended by Cisco. Information on how to do both can be found on the Cisco Guide to Harden Cisco IOS Devices.

Customers unable or unwilling to disable the Telnet protocol can reduce the attack surface by implementing infrastructure access control lists (iACLs). Information on iACLs can be found on the following document: Protecting Your Core: Infrastructure Protection Access Control Lists

Fixed Software 

Cisco IOS and IOS XE Software


To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides a tool, the Cisco IOS Software Checker, that identifies any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory ("First Fixed"). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified ("Combined First Fixed").

Customers can use this tool to perform the following tasks: 
  • Initiate a search by choosing one or more releases from a drop-down menu or uploading a file from a local system for the tool to parse 
  •  Enter the output of the show version command for the tool to parse 
  • Create a custom search by including all previously published Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication   
Cisco will release 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: http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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 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.

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: http://www.cisco.com/en/US/support/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 

There are no fixed software releases at this time. The IOS Software Checker tool will be updated once fixed software becomes available.

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  

This vulnerability was found during the analysis of documents related to the Vault 7 disclosure. 

URL     


In The News is brought to you by WinMill Software, the premier resource for systems development and integration, expert consulting, quality assurance, technology infrastructure, and software resale. For more information, contact a WinMill Account Manager at inquiry@winmill.com or 1-888-711-MILL (6455).