Cisco issues critical patch for Nexus switches to remove hardcoded credentials

Nexus 3000 Series and 3500 Platform switches contain a root account with a static password that can be accessed remotely

Cisco Systems has released software updates for its Nexus 3000 and 3500 switches in order to remove a default administrative account with static credentials that could allow remote attackers to compromise devices.

The account is created at installation time by the Cisco NX-OS software that runs on these switches and it cannot be changed or deleted without affecting the system's functionality, Cisco said in an advisory.

The company rated the issue as critical because authenticating with this account can provide attackers with access to a bash shell with root privileges, meaning that they can fully control the device.

One factor that could potentially limit attacks is that on most NX-OS releases, the default account can only be accessed via Telnet, which is disabled by default. The exception is Nexus 3500 Platform Switches running Cisco NX-OS Software release 6.0(2)A6(1) where the account can also be accessed over SSH (Secure Shell).

The affected devices are: Cisco Nexus 3000 Series switches running NX-OS 6.0(2)U6(1), 6.0(2)U6(2), 6.0(2)U6(3), 6.0(2)U6(4) and 6.0(2)U6(5) and Cisco Nexus 3500 Platform switches running NX-OS 6.0(2)A6(2), 6.0(2)A6(3), 6.0(2)A6(4), 6.0(2)A6(5) and 6.0(2)A7(1).

Cisco has provided patched versions for all of these releases, but the company advises customers to upgrade to NX-OS 6.0(2)U6(5a) for Nexus 3000 switches and 6.0(2)A7(1a) or 6.0(2)A6(5a) for Nexus 3500 switches. That's because these versions also contain patches for two other high-impact vulnerabilities that could lead to denial-of-service conditions.

One of those flaws can be exploited by sending a specific TCP packet to an affected device on a TCP session that is in a TIME_WAIT state. This would cause the TCP stack to reload, resulting in a denial of service.

The vulnerability affects the NX-OS software running on Cisco Nexus 1000V Series, 3000 Series, 4000 Series, 5000 Series, 6000 Series and 7000 Series switches, as well as the Cisco Unified Computing System (UCS).

The second vulnerability can be exploited by sending a crafted SNMP (Simple Network Management Protocol) packet to an affected device, which would cause the SNMP server on the device to restart. Doing this repeatedly could lead a full system restart.

This vulnerability affects Cisco Nexus 5500 Platform Switches, Cisco Nexus 5600 Platform Switches, and Cisco Nexus 6000 Series Switches running Cisco NX-OS Software Release 7.1(1)N1(1).

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.
Lucian Constantin

Lucian Constantin

IDG News Service
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers

MSI P65

This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang

MSI GT76

It really doesn’t get more “gaming laptop” than this.

Jack Jeffries

MSI GS75

As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr

MSI PS63

The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?