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Vulnerability Alert

Cisco Nexus 7000 Frame Forwarding Loop Denial of Service Vulnerability

 
Threat Type:CWE-119: Buffer Errors
IntelliShield ID:29104
Version:1
First Published:2013 April 29 20:32 GMT
Last Published:2013 April 29 20:32 GMT
Port: Not available
CVE:CVE-2013-1226
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:6.1 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:5.5
 
Version Summary:Cisco NX-OS Software running on Nexus 7000 Series Switches contains a vulnerability that could allow an unauthenticated, remote attacker with access to an adjacent network to cause a denial of service condition on a targeted device. Updates are available.
 
 
Description
Cisco NX-OS Software running on Nexus 7000 Series Switches contains a vulnerability that could allow an unauthenticated, remote attacker with access to an adjacent network to cause a denial of service (DoS) condition.

The vulnerability is due to mishandling of a specific type of nonstandard Ethernet frame by the affected software. An unauthenticated, remote attacker with access to an adjacent network could exploit the vulnerability by sending an unspecified crafted nonstandard Ethernet frame to a targeted device. A successful exploit could allow the attacker to cause a frame forwarding loop, resulting in a DoS condition.

Cisco has confirmed the vulnerability in a security notice and has released software updates.
 
Warning Indicators
At the time this alert was first published, the following versions of Cisco NX-OS Software were vulnerable when running on the Nexus 7000 Series Switch:
4.1, 4.1.(2), 4.1.(3), 4.1.(4), 4.1.(5), 4.2.(2a), 4.2(3), 4.2(4), 4.2(6), 4.2(8), 5.0(2a), 5.0(3), 5.0(5), 5.1(1), 5.1(1a), 5.1(3), 5.1(4), 5.1(5), 5.1(6), 5.2(1), 5.2(3a), 5.2(4), 5.2(5), 5.2(7), 5.2(9), 6.0(1), 6.0(2), 6.0(3), 6.0(4), 6.1(1), 6.1(2), 6.1(3)
Later versions of Cisco NX-OS Software may also be affected.
 
IntelliShield Analysis
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.

To exploit this vulnerability, an attacker may require access to trusted, internal networks to send crafted requests to the affected software. This access requirement could limit the likelihood of a successful exploit.
 
Vendor Announcements
Cisco has released a security notice for bug ID CSCug47098 at the following link: CVE-2013-1226
 
Impact
An unauthenticated, remote attacker with access to an adjacent network could exploit the vulnerability to cause a frame forwarding loop, resulting in a DoS condition.
 
Technical Information
The vulnerability is due to mishandling of a specific type of nonstandard Ethernet frame by the affected software.

An unauthenticated, remote attacker with access to an adjacent network could exploit the vulnerability by sending an unspecified crafted nonstandard Ethernet frame to a targeted device. When the malicious frame is processed by the affected device, it could be replicated to all interswitch links, affecting all services running on the device. A successful exploit could allow the attacker to cause a frame forwarding loop, resulting in a DoS condition.
 
Safeguards
Administrators are advised to apply the appropriate updates.

Administrators are advised to allow only trusted users to have network access.

Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

Understanding activity on the network provides information and visibility that can be used to identify potential security incidents. Organizations should log events from devices and review the logged data to provide insight into anomalies or malicious activity. For logging best practices, consult Cisco Guide to Harden Cisco IOS Devices.

Network traffic should be monitored for security-related network activity. NetFlow identifies security-related network activity. For NetFlow configuration details, consult Introduction to Cisco IOS NetFlow - A Technical Overview.

Administrators are advised to monitor affected systems.
 
Patches/Software
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at tac@cisco.com
 
Alert History
 
Initial Release


Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
CiscoCisco NX-OS Software for Nexus 7000 Series Base, 4.1.(2), 4.1.(3), 4.1.(4), 4.1.(5), 4.2.(2a), 4.2(3), 4.2(4), 4.2(6), 4.2(8), 5.0(2a), 5.0(3), 5.0(5), 5.1(1), 5.1(1a), 5.1(3), 5.1(4), 5.1(5), 5.1(6), 5.2(1), 5.2(3a), 5.2(4), 5.2(5), 5.2(7), 5.2(9), 6.0(1), 6.0(2), 6.0(3), 6.0(4), 6.1(1), 6.1(2), 6.1(3)

Associated Products:
N/A




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LEGAL DISCLAIMER
The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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