CVE-2019-1738 : Security Advisory and Response

A potential security weakness in the Network-Based Application Recognition (NBAR) function of Cisco IOS Software and Cisco IOS XE Software could allow a remote attacker to force a device restart, leading to a denial of service situation.

Understanding CVE-2019-1738

This CVE involves a vulnerability in the NBAR feature of Cisco IOS and IOS XE Software, potentially exploited by unauthenticated remote attackers.

What is CVE-2019-1738?

The vulnerability stems from an error in parsing DNS packets, enabling attackers to send manipulated DNS packets through routers with NBAR enabled, causing affected devices to restart.

The Impact of CVE-2019-1738

The vulnerability poses a high availability impact, with a CVSS base score of 8.6, leading to a denial of service condition if successfully exploited.

Technical Details of CVE-2019-1738

This section provides detailed technical insights into the vulnerability.

Vulnerability Description

The flaw in NBAR allows remote unauthenticated attackers to trigger device restarts by sending carefully crafted DNS packets.

Affected Systems and Versions

Cisco IOS and IOS XE Software versions 3.16.0S to 3.18.1iSP are affected.

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Privileges Required: None
Scope: Changed
User Interaction: None

Mitigation and Prevention

Effective strategies to mitigate and prevent exploitation of CVE-2019-1738.

Immediate Steps to Take

Disable NBAR if not essential for operations.
Implement network segmentation to limit the impact of potential attacks.
Monitor network traffic for any suspicious DNS packets.

Long-Term Security Practices

Regularly update and patch Cisco IOS and IOS XE Software to the latest versions.
Conduct security assessments and audits to identify and address vulnerabilities.

Patching and Updates

Apply patches provided by Cisco to address the NBAR vulnerability.