STI: A Security Architecture for IP Telephony

IP电话是一种复杂的应用，涉及多层协议堆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)要求IP电话与公共交换电话网(PSTN)互操作，以及2)要求IP电话与诸如网络地址转换器(NAT)和防火墙等现有网络中间盒一起工作。这些复杂性带来了漏洞，这些漏洞容易受到已知形式的攻击，也可能是新形式的攻击。这项拟议的重点研究的目标是1)对IP电话进行全面的脆弱性分析，2)设计一种安全体系结构来对抗IP电话中各种类型的拒绝服务(DoS)攻击。具体工作如下：首先，采用属性驱动的方法对IP电话进行了详细的脆弱性分析。在此方法中，定义IP电话应用程序对于特定类型的部署必须满足的一组属性。然后，将列举这些漏洞并将其归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。在开发安全体系结构时，我们将重点放在传感器的设计和分析上，以检测和控制DoS攻击。虽然已经对DoS攻击进行了研究，但IP电话技术面临着重大的新挑战。接下来将研究基于特征的异常检测算法和统计异常检测算法。检测算法很复杂，因为攻击可能发生在涉及多个网络设备的多个层，并攻击协议体系结构的控制平面和数据平面。最后，在融合网络中，对IP电话系统的攻击既可以来自互联网，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检，即来自不同协议层和不同网元的各种传感器的数据必须相互关联，以确定攻击类型，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.