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 CSO newsletter!

Error: Please check your email address.

More about CiscoSNMPSSHTelnet

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Lucian Constantin

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

More videos

Blog Posts

Market Place