threat-modeling.md

Threat Model Analysis for wireguard/wireguard-linux

Threat: Key Compromise

Description: An attacker gains unauthorized access to a WireGuard private key. This could be through weak file permissions, system vulnerabilities, or insider threats. With the private key, the attacker can decrypt all traffic secured by this key, impersonate the peer, and gain unauthorized access to protected resources. Impact: Complete loss of confidentiality for communication secured by the compromised key. Full compromise of VPN security. Unauthorized access to internal networks and sensitive data. Affected WireGuard-linux Component: Key management and storage (configuration files, system memory). Risk Severity: Critical Mitigation Strategies: * Implement strong file permissions (e.g., 0600) on private key files. * Utilize secure key generation practices with strong random number generators. * Consider hardware security modules (HSMs) or secure enclaves for sensitive key storage. * Implement and enforce key rotation policies. * Regularly audit key storage and access controls.

Threat: Buffer Overflow in Kernel Module

Description: A buffer overflow vulnerability exists within the wireguard-linux kernel module code. An attacker crafts malicious network packets or exploits other input vectors to trigger the overflow. This can overwrite kernel memory, potentially leading to arbitrary code execution within the kernel, data corruption, or denial of service. Exploitation can lead to full system compromise. Impact: Arbitrary code execution in the kernel. Full system compromise. Data corruption. Denial of service. Confidentiality breaches through memory manipulation. Affected WireGuard-linux Component: wireguard-linux kernel module (packet processing functions, input validation). Risk Severity: Critical Mitigation Strategies: * Keep the wireguard-linux kernel module updated to the latest stable version with security patches. * Utilize memory safety tools and fuzzing during development and testing to identify and fix buffer overflow vulnerabilities. * Enable kernel hardening features like ASLR and SSP. * Regularly monitor security advisories related to the Linux kernel and WireGuard.

Threat: Kernel Module Manipulation/Replacement

Description: An attacker with root privileges replaces the legitimate wireguard-linux kernel module with a malicious version. This malicious module can intercept and modify all VPN traffic, inject data, bypass security checks, and perform arbitrary actions at the kernel level, effectively taking complete control over VPN communications and potentially the system itself. Impact: Complete compromise of VPN integrity and confidentiality. Arbitrary code execution in the kernel. Data manipulation and injection. Full system compromise. Affected WireGuard-linux Component: wireguard-linux kernel module (the entire module itself). Risk Severity: Critical Mitigation Strategies: * Implement robust system security measures to prevent unauthorized root access. * Utilize kernel module signing and verification mechanisms to ensure module integrity. * Regularly audit system integrity and monitor for unexpected kernel module changes. * Employ security tools that detect rootkit activity and kernel module manipulation.

Threat: Exploiting Kernel Module Vulnerability for DoS

Description: A vulnerability in the wireguard-linux kernel module (e.g., a bug leading to a crash or hang) is exploited by an attacker. By sending crafted packets or triggering specific conditions, the attacker can cause the kernel module to malfunction, leading to a denial of service for the VPN and potentially the entire system by crashing the kernel or making it unresponsive. Impact: VPN service becomes unavailable. System instability or crash, leading to broader service disruption. Affected WireGuard-linux Component: wireguard-linux kernel module (vulnerable code paths). Risk Severity: Critical Mitigation Strategies: * Keep the wireguard-linux kernel module updated to the latest stable version with security patches. * Utilize fuzzing and vulnerability scanning to proactively identify and fix potential DoS vulnerabilities in the kernel module. * Implement robust system monitoring to detect and respond to unexpected system behavior indicating a DoS attack or kernel module malfunction. * Consider kernel hardening techniques to limit the impact of kernel vulnerabilities.

Threat: Memory Leak of Sensitive Data

Description: A vulnerability in the wireguard-linux kernel module code leads to the unintentional exposure of sensitive data from kernel memory. This could include cryptographic keys, plaintext traffic fragments, or other sensitive information processed by WireGuard. An attacker exploiting this vulnerability could read kernel memory to extract this data, potentially leading to key compromise and loss of confidentiality. Impact: Potential exposure of confidential data, including cryptographic keys and plaintext traffic. Could lead to key compromise and significant loss of confidentiality. Affected WireGuard-linux Component: wireguard-linux kernel module (memory management functions, data processing functions). Risk Severity: High Mitigation Strategies: * Keep the wireguard-linux kernel module updated to the latest stable version with security patches. * Utilize memory safety tools and static analysis during development and testing of applications interacting with WireGuard to identify potential memory leaks. * Enable kernel hardening features to mitigate the impact of memory vulnerabilities. * Regularly monitor security advisories related to the Linux kernel and WireGuard.

Threat: Configuration Tampering

Description: An attacker gains unauthorized access to the system and modifies WireGuard configuration files (e.g., wg0.conf). They could change allowed IPs, endpoint addresses, or other parameters to weaken security, redirect traffic to malicious destinations, or gain unauthorized access to internal networks by altering allowed IPs or DNS settings. Impact: Compromised VPN security posture. Potential for unauthorized access to internal networks, data interception, or redirection of traffic to attacker-controlled systems. Affected WireGuard-linux Component: Configuration file parsing and application (configuration files stored on the filesystem). Risk Severity: High Mitigation Strategies: * Implement strong access controls on WireGuard configuration files (restrict write access to authorized users only). * Use file integrity monitoring systems to detect unauthorized changes to configuration files. * Consider using configuration management tools to enforce desired configurations and detect deviations. * Regularly audit configuration files for unexpected changes.

Threat: Denial of Service (DoS) Attack against WireGuard Endpoint

Description: An attacker floods the WireGuard endpoint with a high volume of network traffic (e.g., UDP packets). This overwhelms the endpoint's resources (CPU, network bandwidth, memory), making it unable to process legitimate traffic and effectively denying VPN service to legitimate users, disrupting applications and services relying on the VPN connection. Impact: VPN service becomes unavailable, disrupting critical applications and services relying on the VPN connection. Business disruption and potential financial losses. Affected WireGuard-linux Component: WireGuard endpoint (network interface, packet processing). Risk Severity: High Mitigation Strategies: * Implement rate limiting on the WireGuard endpoint. * Use traffic filtering and firewall rules to block malicious traffic patterns. * Deploy intrusion detection/prevention systems (IDS/IPS) to mitigate DoS attacks. * Consider cloud-based DDoS protection services for internet-facing WireGuard endpoints. * Properly size the WireGuard endpoint infrastructure to handle expected traffic loads and potential surges.