Multiple Cisco Products Snort Modbus Denial of Service Vulnerability [CVE-2022-20685]

CVE number – CVE-2022-20685

A vulnerability in the Modbus preprocessor of the Snort detection engine could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to an integer overflow while processing Modbus traffic. An attacker could exploit this vulnerability by sending crafted Modbus traffic through an affected device. A successful exploit could allow the attacker to cause the Snort process to hang, causing traffic inspection to stop.

Cisco has released software updates that address this vulnerability.

There are no workarounds that address this vulnerability.

Vulnerable Products

This vulnerability affects all open source Snort project releases earlier than Release 2.9.19 and Release 3.1.11.0. For more information, see the Snort website.

Note: Modbus inspection is enabled by default.

This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco software:

• Cyber Vision Software
• Firepower Threat Defense (FTD) Software – All platforms
• Meraki MX Series Software

This vulnerability affects the following Cisco products if they are running a release earlier than the first fixed release of Cisco Unified Threat Defense (UTD) Snort Intrusion Prevention System (IPS) Engine for Cisco IOS XE Software or Cisco UTD Engine for Cisco IOS XE SD-WAN Software:

• 1000 Series Integrated Services Routers (ISRs)
• 4000 Series Integrated Services Routers (ISRs)
• Catalyst 8000V Edge Software
• Catalyst 8200 Series Edge Platforms
• Catalyst 8300 Series Edge Platforms
• Catalyst 8500 Series Edge Platforms
• Catalyst 8500L Series Edge Platforms
• Cloud Services Routers 1000V
• Integrated Services Virtual Routers (ISRv)

Note: UTD is not installed on these devices by default.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-dos-9D3hJLuj