Facebook Google Plus Twitter LinkedIn YouTube RSS Menu Search Resource - BlogResource - WebinarResource - ReportResource - Eventicons_066 icons_067icons_068icons_069icons_070

Tenable Blog

Subscribe

Cisco Smart Install - How to Prevent Attacks on Switches

There’s been a flurry of activity around the Cisco Smart Install feature recently. Last week, we posted a tech blog about CVE-2018-0171, a critical vulnerability in Cisco’s Smart Install feature that called for immediate mitigation as proof-of-concept code was released publicly. Now, a wave of attacks has moved through data centers across the internet targeting Cisco switches with Smart Install in various countries across the globe. This time around, attackers are (mis)using the Smart Install protocol with mal intent on Cisco’s switches that are open with Smart Install support. Once the attacker gains access, they rewrite the Cisco IOS image on the switches and change the configuration file. One such attack leaves a message that reads “Do not mess with our elections” as the message banner. The switch then becomes unavailable. 

Impact assessment

According to Cisco Talos, more than 168,000 devices found on Shodan have this vulnerability. The rate at which Cisco switches are being taken down isn’t known at this time. But, the loss of a switch can have a small to enormous impact on a data center, depending on the network architecture. Cisco switches utilized for internet connectivity may cause lost connectivity if they’re taken down. Any business that hasn’t mitigated their switches could experience a loss in connectivity affecting sales, productivity or customer interaction.

Exploitation

According to Cisco, “The Cisco Smart Install protocol can be abused to modify the Trivial File Transfer Protocol (TFTP) server setting, exfiltrate configuration files via TFTP, modify the configuration file, replace the IOS image, and set up accounts, allowing for the execution of IOS commands. Although this is not a vulnerability in the classic sense, the misuse of this protocol is an attack vector that should be mitigated immediately.”

Cisco released an advisory on the security of Smart Install last year and reiterated their advice last week.

Urgently required actions

Cisco and Tenable suggest immediate mitigation of Cisco switches by:

  • Limiting access through an Access Control List
  • Limiting access to TCP 4786 port
  • Disabling the Smart Install Client on the switch

Identifying affected systems

Get more information

Related Articles

Cybersecurity News You Can Use

Enter your email and never miss timely alerts and security guidance from the experts at Tenable.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Try Tenable Web App Scanning

Enjoy full access to our latest web application scanning offering designed for modern applications as part of the Tenable One Exposure Management platform. Safely scan your entire online portfolio for vulnerabilities with a high degree of accuracy without heavy manual effort or disruption to critical web applications. Sign up now.

Your Tenable Web App Scanning trial also includes Tenable Vulnerability Management and Tenable Lumin.

Buy Tenable Web App Scanning

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

5 FQDNs

$3,578

Buy Now

Try Tenable Lumin

Visualize and explore your exposure management, track risk reduction over time and benchmark against your peers with Tenable Lumin.

Your Tenable Lumin trial also includes Tenable Vulnerability Management and Tenable Web App Scanning.

Buy Tenable Lumin

Contact a Sales Representative to see how Tenable Lumin can help you gain insight across your entire organization and manage cyber risk.

Try Tenable Nessus Professional Free

FREE FOR 7 DAYS

Tenable Nessus is the most comprehensive vulnerability scanner on the market today.

NEW - Tenable Nessus Expert
Now Available

Nessus Expert adds even more features, including external attack surface scanning, and the ability to add domains and scan cloud infrastructure. Click here to Try Nessus Expert.

Fill out the form below to continue with a Nessus Pro Trial.

Buy Tenable Nessus Professional

Tenable Nessus is the most comprehensive vulnerability scanner on the market today. Tenable Nessus Professional will help automate the vulnerability scanning process, save time in your compliance cycles and allow you to engage your IT team.

Buy a multi-year license and save. Add Advanced Support for access to phone, community and chat support 24 hours a day, 365 days a year.

Select Your License

Buy a multi-year license and save.

Add Support and Training

Try Tenable Nessus Expert Free

FREE FOR 7 DAYS

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Already have Tenable Nessus Professional?
Upgrade to Nessus Expert free for 7 days.

Buy Tenable Nessus Expert

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Select Your License

Buy a multi-year license and save more.

Add Support and Training