CVE-2018-0173 : Security Advisory and Response

A weakness in the functionality of the Cisco IOS Software and Cisco IOS XE Software could potentially lead to a denial of service (DoS) situation by enabling an unauthorized remote attacker to initiate a reload of the affected device.

Understanding CVE-2018-0173

This CVE involves a vulnerability in the process of restoring encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets in Cisco IOS and IOS XE Software.

What is CVE-2018-0173?

The vulnerability allows an attacker to force a device reload by sending a crafted DHCPv4 packet, resulting in a DoS condition due to insufficient validation of encapsulated option 82 information.

The Impact of CVE-2018-0173

Exploitation of this vulnerability could lead to a denial of service (DoS) situation where Relay Reply is compromised, affecting the availability of the device.

Technical Details of CVE-2018-0173

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

The vulnerability arises from incomplete input validation of encapsulated option 82 information in DHCPv4 packets, allowing an attacker to trigger a device reload.

Affected Systems and Versions

Product: Cisco IOS and IOS XE
Versions: Cisco IOS and IOS XE

Exploitation Mechanism

Attacker sends a meticulously crafted DHCPv4 packet to the affected device
Device forwards the packet to a DHCPv4 server
Error occurs during processing of option 82 information, leading to a device reload

Mitigation and Prevention

It is crucial to take immediate steps to address and prevent the exploitation of this vulnerability.

Immediate Steps to Take

Apply vendor-supplied patches promptly
Implement network segmentation to limit the impact of potential attacks
Monitor network traffic for any suspicious DHCPv4 packets

Long-Term Security Practices

Regularly update and patch all software and firmware in the network
Conduct security training for employees to raise awareness of potential threats

Patching and Updates

Regularly check for updates and patches from Cisco
Apply patches as soon as they are available to mitigate the risk of exploitation