CVE-2019-1740 : What You Need to Know

A security flaw in Cisco IOS and Cisco IOS XE Software related to the Network-Based Application Recognition (NBAR) feature allows an attacker to force a device to reboot by sending specially crafted DNS packets. This can lead to a denial of service (DoS) situation.

Understanding CVE-2019-1740

This CVE involves a vulnerability in Cisco IOS and IOS XE Software that can be exploited to cause a denial of service by triggering a device reboot.

What is CVE-2019-1740?

The vulnerability in Cisco IOS and IOS XE Software enables an unauthenticated attacker to send manipulated DNS packets through affected routers with NBAR enabled, resulting in a device reboot.

The Impact of CVE-2019-1740

The flaw allows attackers to remotely force a device reboot, leading to a DoS situation. The severity is rated as HIGH with a CVSS base score of 8.6.

Technical Details of CVE-2019-1740

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The flaw in NBAR feature of Cisco IOS and IOS XE Software allows attackers to exploit a parsing issue in DNS packets, causing affected devices to reload.

Affected Systems and Versions

Products: Cisco IOS and Cisco IOS-XE Software
Versions: 3.16.0S to 3.18.1iSP

Exploitation Mechanism

To exploit the vulnerability, attackers need to send specially crafted DNS packets through routers running the affected versions with NBAR enabled.

Mitigation and Prevention

Protect your systems from CVE-2019-1740 with the following steps:

Immediate Steps to Take

Disable NBAR feature if not essential
Implement firewall rules to restrict DNS traffic
Apply access control lists to filter DNS packets

Long-Term Security Practices

Regularly update and patch Cisco IOS and IOS XE Software
Monitor network traffic for any suspicious DNS activities

Patching and Updates

Apply patches provided by Cisco to address the vulnerability