Cisco Smart Install Protocol misuse could expose critical infrastructure to attacks

Pierluigi Paganini April 06, 2018

Cisco PSIRT has published a new security advisory for abuse of the Smart Install protocol, the IT giant has identified hundreds of thousands of exposed devices online.

Cisco is advising organizations that hackers could target its switches via the Smart Install protocol. The IT giant has identified hundreds of thousands of exposed devices and warned critical infrastructure using them of potential risks.

Smart Install is a legacy plug-and-play configuration and image-management feature that provides zero-touch deployment for new switches.

In February 2017, researchers from Cisco Talos observed a spike in Internet scans attempting to discover unprotected Cisco devices that had Smart Install feature enabled.

Research has indicated that malicious actors may be leveraging detailed knowledge of the Smart Install Protocol to obtain copies of customer configurations from affected devices.” reported Cisco Talos last year.

“The attack leverages a known issue with the Smart Install protocol. Cisco PSIRT has published a security response to this activity. Abuse of the Smart Install protocol can lead to modification of the TFTP server setting, exfiltration of configuration files via TFTP, replacement of IOS image and potentially execution of IOS commands.”

The researchers also reported that attackers were using an open source tool to scan for affected systems, called the Smart Install Exploitation Tool (SIET),

Now Cisco PSIRT has published a new security advisory for abuse of the protocol.

“Cisco is aware of a significant increase in Internet scans attempting to detect devices where, after completing setup, the Smart Install feature remains enabled and without proper security controls. This could leave the involved devices susceptible to misuse of the feature. ” reads the new security advisory.

“Several researchers have reported on the use of Smart Install (SMI) protocol messages toward Smart Install clients, also known as integrated branch clients (IBC), allowing an unauthenticated, remote attacker to change the startup-config file and force a reload of the device, load a new IOS image on the device, and execute high-privilege CLI commands on switches running Cisco IOS and IOS XE Software.”

At the end of March, Cisco patched more than 30 vulnerabilities in its IOS software, including the CVE-2018-0171 flaw that affects the Smart Install feature of Cisco IOS Software and Cisco IOS XE Software. The flaw could be exploited by an unauthenticated, remote attacker to cause a reload of a vulnerable device or to execute arbitrary code on an affected device.

“The vulnerability is due to improper validation of packet data. An attacker could exploit this vulnerability by sending a crafted Smart Install message to an affected device on TCP port 4786.” reads the security advisory published by Cisco.

Cisco experts revealed they had identified roughly 250,000 vulnerable Cisco devices with TCP port 4786 open. A recent scan performed by Cisco revealed 168,000 systems are exposed online.

CISCO Smart Install scans

Since Embedi has released technical details and proof-of-concept (PoC) code for the exploitation of the CVE-2018-0171 vulnerability, risk of attacks has dramatically increased.

At the time, there is no evidence that CVE-2018-0171 has been exploited in attacks.

Cisco published recommendations for preventing such kind of attacks and urged customers to disable the feature if not needed.

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Pierluigi Paganini

(Security Affairs – hacking, Cisco)

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