STI: A Security Architecture for IP Telephony

IP电话是一个复杂的应用程序，涉及多层协议栈和多个网络设备之间的交互。另外两个因素加剧了这种复杂性。1) IP电话与公共交换电话网（PSTN）互操作的要求；2)IP电话与现有网络中继机（如网络地址转换器（nat）和防火墙）一起工作的要求。这些复杂性引入了容易受到已知攻击和新形式攻击的漏洞。本研究的目标是1)对IP电话进行全面的漏洞分析，2)设计一个安全体系结构来应对IP电话中的各种类型的拒绝服务（DoS）攻击。工作将进行如下：首先使用属性驱动的方法对IP电话进行详细的漏洞分析。在这种方法中，定义一组属性，IP电话应用程序必须满足特定类型的部署。然后，将列出这些漏洞，并将其分类为使用相应攻击违反这些属性的潜在方法。此漏洞分析将构成设计安全体系结构的基础。在开发安全架构时，我们的重点将放在传感器的设计和分析上，以检测和控制DoS攻击。当DoS攻击被研究时，IP电话提出了重大的新挑战。接下来将研究基于签名和统计的异常检测算法。由于攻击可以发生在涉及多个网络设备的多层，并且攻击协议体系结构的控制平面和数据平面，因此检测算法比较复杂。最后，在融合网络中，对IP电话系统的攻击既可以来自Internet，也可以来自PSTN。一旦攻击停止，可以快速恢复的恢复算法将被设计出来。整个体系结构将涉及跨层自省，也就是说，来自不同协议层和不同网络元素的各种传感器的数据将必须相互关联，以确定攻击的类型，从而确定所需的响应。

IP telephony is a complex application involving multiple layers of the protocols stack and interactions among multiple network devices. The complexity is exacerbated by two additional factors . 1) the requirement that IP telephony interoperate with the Public Switched Telephone Network (PSTN) and 2) the requirement that IP telephony functions with existing network middle-boxes such as network address translators (NATs) and firewalls. These complexities introduce vulnerabilities that are prone to both known and perhaps, new forms of attacks. The goals of this proposed focused research are 1) to perform a comprehensive vulnerability analysis of IP telephony and 2) to design a security architecture to counter various types of denial-of-service (DoS) attacks in IP telephony. The work will proceed as follows: first carry out a detailed vulnerability analysis of IP telephony using a property driven approach. In this approach, define a set of properties that an IP telephony application must satisfy for a specific type of deployment. Then the vulnerabilities will be then enumerated and classified as potential ways to violate these properties using a corresponding attack. This vulnerability analysis will form the basis for designing the security architecture. In developing the security architecture, our focus will be in the design and analysis of sensors to detect and control DoS attacks. While DoS attacks have been studied, IP telephony presents significant new challenges. Next will be an investigation of both signature-based and statistical anomaly detection algorithms. The detection algorithms are complex because the attacks can occur at multiple layers involving multiple network devices and attack both the control and data plane of the protocol architecture. Finally, in a converged network, an attack to the IP telephony system can be made from both the Internet as well as the PSTN. Recovery algorithms that can quickly recover once the attack has ceased will be designed. The overall architecture will involve cross-layer introspection, i.e., the data from the various sensors at the different protocol layers and at the different network elements will have to correlated to determine the type of attack and hence the desired response.