CVE-2015-6111 in Windows
Summary
by MITRE
IPSec in Microsoft Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT Gold and 8.1, and Windows 10 Gold and 1511 mishandles encryption negotiation, which allows remote authenticated users to cause a denial of service (system hang) via crafted IP traffic, aka "Windows IPSec Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 11/18/2024
The vulnerability identified as CVE-2015-6111 represents a critical weakness in the Internet Protocol Security implementation within various Microsoft Windows operating systems including Windows 8, Windows 8.1, Windows Server 2012, Windows RT, and Windows 10. This flaw specifically affects the IPSec encryption negotiation process, creating a condition where legitimate network traffic can be exploited to trigger system instability. The vulnerability operates at the network protocol level, targeting the core security mechanisms that ensure secure communication between network endpoints. The issue stems from improper handling of encryption parameters during the IPSec negotiation phase, which occurs when establishing secure connections between network devices. This misconfiguration allows attackers to craft specific IP packets that, when processed by vulnerable systems, result in system hang conditions rather than the expected secure connection establishment.
The technical nature of this vulnerability can be classified under CWE-129, which deals with improper validation of input boundaries, and more specifically relates to improper handling of cryptographic negotiation parameters. The flaw manifests when the IPSec implementation fails to properly validate or process the encryption algorithms and parameters presented by remote peers during the security association negotiation process. This allows attackers to send specially crafted packets containing malformed or unexpected encryption parameters that cause the system's IPSec service to enter an unrecoverable state. The vulnerability does not require complex exploitation techniques but rather relies on the system's failure to properly handle edge cases in the cryptographic negotiation protocol. Attackers can leverage this weakness to perform denial of service attacks against targeted systems without requiring elevated privileges or specific user interaction, making it particularly dangerous in enterprise environments where network availability is critical.
The operational impact of CVE-2015-6111 extends beyond simple service disruption, as the system hang condition can lead to complete network connectivity loss for affected systems. In corporate environments, this vulnerability can compromise network infrastructure by causing cascading failures when multiple systems become unresponsive simultaneously. The vulnerability affects systems that rely on IPSec for secure communication, including VPN connections, network authentication services, and secure file transfers. Organizations using Windows-based infrastructure for remote access, secure communications, or network segmentation are particularly vulnerable to this attack vector. The attack can be executed remotely by authenticated users who have network access to the vulnerable systems, making it difficult to prevent through traditional network segmentation approaches. The impact is significant enough that it can disrupt business operations, particularly in environments where network availability is critical for maintaining service continuity and operational effectiveness.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems to address the underlying cryptographic negotiation flaw. Microsoft released security updates that corrected the IPSec implementation to properly validate encryption parameters during negotiation processes. Organizations should implement network monitoring to detect unusual traffic patterns that may indicate exploitation attempts, particularly focusing on IPSec-related packets and connection attempts. Network segmentation strategies can help limit the scope of potential attacks by isolating vulnerable systems from critical network resources. The implementation of intrusion detection systems capable of identifying malformed IPSec traffic can provide early warning of exploitation attempts. Additionally, administrators should consider disabling IPSec services on systems where they are not required, reducing the attack surface. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks, and represents a classic example of how protocol implementation flaws can create significant security risks. Organizations should also review their network security policies to ensure proper access controls and authentication mechanisms are in place to limit potential exploitation of this vulnerability.