CVE-2019-1739 : Exploit Details and Defense Strategies

A security vulnerability in Cisco IOS Software and Cisco IOS XE Software's Network-Based Application Recognition (NBAR) feature could allow a remote attacker to cause a denial of service (DoS) by forcing the affected device to reload.

Understanding CVE-2019-1739

This CVE involves a vulnerability in the NBAR feature of Cisco IOS and IOS XE Software that could be exploited by sending crafted DNS packets.

What is CVE-2019-1739?

The vulnerability in the NBAR feature of Cisco IOS and IOS XE Software allows remote attackers to trigger a device reload by exploiting a parsing issue with DNS packets.

The Impact of CVE-2019-1739

If successfully exploited, this vulnerability could lead to a denial of service (DoS) situation by causing the affected device to reload.

Technical Details of CVE-2019-1739

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability arises from a parsing problem with DNS packets in the NBAR feature of Cisco IOS and IOS XE Software.

Affected Systems and Versions

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

Exploitation Mechanism

To exploit this vulnerability, the attacker needs to send specifically crafted DNS packets through routers with NBAR enabled and running a vulnerable version.

Mitigation and Prevention

Protecting systems from this vulnerability requires immediate steps and long-term security practices.

Immediate Steps to Take

Disable NBAR if not essential for network operations
Implement network segmentation to limit the impact of potential attacks

Long-Term Security Practices

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

Patching and Updates

Ensure that affected systems are updated with the latest patches provided by Cisco to mitigate the vulnerability.