Friday, January 26, 2018

Intranet DDoS attacks

As on a Darkling Plain: Network Survival in an Age of Pervasive DDoS talk by Steinthor Bjarnason at the recent NANOG 71 conference. The talk discusses the threat that the proliferation of network connected devices in enterprises create when they are used to launch denial of service attacks. Last year's Mirai attacks are described, demonstrating the threat posed by mixed mode attacks where a compromised host is used to infect large numbers devices on the corporate network.
The first slide from the talk shows a denial attack launched against an external target, launched from infected video surveillance cameras scattered throughout the the enterprise network. The large volume of traffic fills up external WAN link and overwhelms stateful firewalls.
The second slide shows an attack targeting critical internal services that can have been identified by reconnaissance from the compromised devices. In addition, scanning activity associated with reconnaissance for additional devices can itself overload internal resources and cause outages.

In both cases, most of the critical activity occurs behind the corporate firewall, making it extremely challenging to detect and mitigate these threats.

The talk discusses a number of techniques that service providers use to secure their networks that enterprises will need to adopt in order to meet this challenge. In particular, "utilizing flow telemetry to analyze external and internal traffic. This is necessary for attack detection, classification and traceback."

Instrumentation needs to be built into every network device in order to provide the comprehensive visibility required to address these challenges. sFlow is a scaleable streaming telemetry solution built into a wide variety of devices, from low cost edge switches to high end chassis routers. Network vendors that support sFlow include: A10, Aerohive, AlexalA, ALUe, Allied Telesis, Arista, Aruba, Big Switch, Brocade, Cisco, Cumulus, DCN, Dell, D-Link, Edge-Core, Enterasys, Extreme, F5, Fortinet, HPE, Hitachi, Huawei, IBM, IP Infusion, Juniper, NEC, Netgear, OpenSwitch, Open vSwitch, Oracle, Pica8, Plexxi, Pluribus, Proxim, Quanta, Silicom, SMC, ZTE, and ZyXEL.

Selecting devices that support sFlow simplifies operations by ensuring that the visibility needed to effectively manage the network is integrated into the fabric and deployed pervasively. Attempting to add visibility later is complex, expensive, and results in limited coverage.

There are a number of examples of DDoS mitigation using sFlow on this blog. While many of the examples focus on external DDoS attacks, the techniques are equally applicable to the internal network.