CVE-2019-1849 : Exploit Details and Defense Strategies

Cisco IOS XR Software BGP MPLS-Based EVPN Denial of Service Vulnerability

Understanding CVE-2019-1849

This CVE involves a weakness in the implementation of Cisco IOS XR Software's Border Gateway Patrol (BGP) Multiprotocol Label Switching (MPLS)-based Ethernet VPN (EVPN), potentially leading to a denial of service (DoS) attack.

What is CVE-2019-1849?

The vulnerability allows an adjacent attacker to exploit a flaw in the software processing of specific EVPN routing information, causing a DoS condition on the affected device.

The Impact of CVE-2019-1849

Attack Complexity: Low
Attack Vector: Adjacent Network
Base Score: 7.4 (High)
Availability Impact: High
Scope: Changed
The vulnerability could result in system instability and the inability to process or forward network traffic.

Technical Details of CVE-2019-1849

The following technical details provide insight into the vulnerability.

Vulnerability Description

The vulnerability lies in the BGP MPLS-Based EVPN implementation of Cisco IOS XR Software.
It allows an unauthenticated attacker to trigger a DoS condition by injecting harmful traffic patterns.

Affected Systems and Versions

Product: Cisco IOS XR Software
Vendor: Cisco
Version: Unspecified

Exploitation Mechanism

Attacker injects harmful traffic patterns into the targeted EVPN network.
Successful exploitation crashes the l2vpn_mgr process on PE devices in the same EVPN instance.

Mitigation and Prevention

Steps to address and prevent the CVE-2019-1849 vulnerability.

Immediate Steps to Take

Apply vendor-provided patches or updates promptly.
Implement network segmentation to limit the impact of potential attacks.

Long-Term Security Practices

Regularly monitor and update network security measures.
Conduct security audits and assessments to identify vulnerabilities.

Patching and Updates

Stay informed about security advisories from Cisco.
Regularly update and patch affected systems to mitigate risks.