Details

• ID: CM0014
• Version: 1.0
• Created: 14 March 2025
• Modified: 14 March 2025
• Type: Disable
• Status: Active

Intended Outcome

Disabling the Cisco Smart Install feature blocks adversary collection of network configuration files and execution of arbitrary commands.

Introduction

The Cisco Smart Install Client is a legacy utility designed to allow no-touch installation of new Cisco equipment, specifically Cisco switches. Adversaries may abuse this feature to access, copy, or poison a client's startup-config file or maliciously modify the Cisco IOS to enable persistence.

Preparation

• Upgrade Cisco devices to latest possible Internetworking Operating System (IOS) release.

Risks

• This countermeasure increases the risk of breaking legitimate functionality.
• Switch software updates and configuration changes must be performed manually when Smart Install is disabled.
• Manual operations increase the likelihood of errors that could cause network inaccessibility or downtime.
• Manual operations are more labor-intensive than over-the-network operations.
• This countermeasure may result in excess resource use.

Guidance

• Determine whether Smart Install is Enabled
• Investigate Evidence of Smart Install Abuse
• Analyze traffic and device logs to determine whether unauthorized changes were made to startup-config, Cisco IOS, or the tfcp-server.
• Organizations should preserve a copy of the tampered configuration file or any additional evidence of abuse during the incident response investigation.
• Isolate and Restore Affected Device(s)
• If network administrators determine a network device was abused, they should isolate the affected device from the network.
• Before bringing the device back online, teams should reverse changes made by the adversary by restoring the device's image and configuration to a secure state. This process may include the use of a known good configuration backup, performing a factory reset of the device, and ensuring the latest vendor patches are applied.
• Restrict and/or Disable Smart Install
• Network administrators should verify Smart Install is using TCP port 4786 before then blocking it.
• If Smart Install cannot be disabled, organizations should implement interface access control lists (ACLs) and Control Plane Policing (CoPP) to drop traffic.
• Harden
• System administrators should ensure all patches for known security vulnerabilities associated with their network devices are applied.
• Migrate to new technology to replace the Smart Install legacy protocol, specifically Cisco Network Plug and Play for securely configuring new switches.
• Network administrators should consult Cisco's Guide to Harden Cisco IOS Devices for additional instructions for improving device security.

References

• Smart Install Descriptions Restrictions for Smart Install | https://www.cisco.com/c/en/us/td/docs/switches/lan/smart_install/configuration/guide/smart_install/concepts.html#23355