CVE-2017-3857 : Vulnerability Insights and Analysis
Learn about CVE-2017-3857 affecting Cisco IOS and IOS XE versions 12.0 to 12.4 and 15.0 to 15.6, and 3.1 to 3.18. Understand the L2TP parsing function weakness and how to mitigate the DoS risk.
Cisco IOS and IOS XE versions 12.0 to 12.4 and 15.0 to 15.6, and 3.1 to 3.18 respectively, contain a vulnerability in the Layer 2 Tunneling Protocol (L2TP) parsing function that could lead to a denial of service (DoS) attack.
Understanding CVE-2017-3857
This CVE identifies a weakness in Cisco IOS and IOS XE that could allow unauthorized attackers to cause a device reload, resulting in a DoS situation.
What is CVE-2017-3857?
The vulnerability in the L2TP parsing function of Cisco IOS and IOS XE could be exploited by sending a specially crafted L2TP packet to the device, causing it to reload and leading to a DoS scenario.
The Impact of CVE-2017-3857
If successfully exploited, this vulnerability allows attackers to force affected devices to reload, resulting in a denial of service situation. The root cause is the inadequate validation of L2TP packets.
Technical Details of CVE-2017-3857
Cisco IOS and IOS XE are affected by a weakness in the L2TP parsing function, leading to potential DoS attacks.
Vulnerability Description
The vulnerability stems from insufficient validation of L2TP packets, allowing attackers to send crafted packets to trigger device reloads.
Affected Systems and Versions
- Vulnerable versions include Cisco IOS 12.0 to 12.4 and 15.0 to 15.6, and Cisco IOS XE 3.1 to 3.18.
- Devices with L2TP feature activated and configured as L2TPv2 or L2TPv3 endpoints are at risk.
Exploitation Mechanism
- Attackers exploit the vulnerability by sending specially crafted L2TP packets to the device, causing it to reload and leading to a DoS situation.
Mitigation and Prevention
Taking immediate steps and implementing long-term security practices are crucial to mitigate the risks associated with CVE-2017-3857.
Immediate Steps to Take
- Disable the L2TP feature if not required to reduce the attack surface.
- Regularly monitor and apply security patches provided by Cisco.
Long-Term Security Practices
- Implement network segmentation to limit the impact of potential attacks.
- Conduct regular security assessments and audits to identify and address vulnerabilities.
Patching and Updates
- Apply the necessary patches and updates released by Cisco to address the vulnerability and enhance system security.