CVE-2018-0173

CVE-2018-0173 is a high-severity (CVSS 8.6) vulnerability in Cisco IOS and IOS XE Software. CISA added it to the Known Exploited Vulnerabilities catalog on March 3, 2022, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by March 17, 2022. CISA does not currently list it as used in ransomware campaigns. Cisco has 102 vulnerabilities in the KEV catalog, 7 of them linked to ransomware.

A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a Relay Reply denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device, which the device would then forward to a DHCPv4 server. When the affected software processes the option 82 information that is encapsulated in the response from the server, an error could occur. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg62754.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

• http://www.securityfocus.com/bid/103545
• http://www.securitytracker.com/id/1040591
• https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04
• https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2
• https://www.tenable.com/security/research/tra-2018-06
• http://www.securityfocus.com/bid/103545
• http://www.securitytracker.com/id/1040591