Threats Against WS-Discovery

WSD is a multicast discovery protocol to locate services on a local area network (LAN). However, due to device vendors’ design flaw in the implementation, when a normal IP address sends a service discovery packet, devices will also respond to the request. If exposed on the Internet, these devices will be possibly exploited for DDoS reflection attacks. In February 2019, security researchers 1 from Baidu published an article 2 about WSD reflection attacks. This is the first report we have read about such attacks. In a post 3 , ZDNet mentioned that WSD reflection attacks were first reported in May, and in August, many organizations began to use this protocol to launch DDoS attacks. According to Akamai, one of its customers in the gaming industry suffered a WSD reflection attack weighing in at 35 Gbps at peak bandwidth.

Around the world, about 910,000 IP addresses (80% (730,000) were video surveillance devices) provided the WSD service and were thus at risk of being exploited to launch DDoS attacks.

In this section, we analyzed threats against three major protocols.

Threats Against Telnet

According to data from NSFOCUS’s threat hunting system, Telnet (available on port 23), targeted by a total of 120,000 attack sources, was the IoT protocol most favored by attackers1 . Figure 7-3 shows the activity trend of Telnet attack sources from March to October in 2019. We can see that the number of Telnet-based attacks increased month by month from March to August, with August seeing the most attack sources (over 60,000) that carried out more than 50,000 weak password detection activities. In addition, June witnessed the most sample download activities (more than 40,000). Overall, attack sources were on the decline in the latter half of 2019.

Finding 1: In 2019, over 30 types of IoT vulnerability exploits were captured, most of which targeted remote command execution vulnerabilities. Though hundreds of to thousands of IoT vulnerabilities are unveiled each year, only a few can exert an extensive impact. Attackers were keen on targeting devices (routers and video surveillance devices) exposed in large quantities, in a bid to broaden their influence.

Finding 2: IoT devices, especially cameras and routers, were major targets of Telnet weak password cracking attacks.

Finding 3: Since security researchers from Baidu disclosed that the Web Services Dynamic Discovery (WSD) protocol could be exploited for DDoS reflection attacks, there has been a notable increase in reflection attack events based on this protocol in the latter half of 2019. Since mid-August, WSD reflection attacks captured by us have been on the rise. Worse still, September has witnessed a sharp increase in such attacks. All parties concerned, including security vendors, service providers, and telecom carriers, should pay due attention to this type of threats.

Finding 4: Approximately 2.28 million IoT devices (port 1900) worldwide had the UPnP/SSDP service publicly accessible and were thus at risk of being exploited to launch DDoS attacks, an decrease of 22% from 2018.The UPnP port mapping service, exposed on about 390,000 IoT devices, was likely to be abused as a proxy or render intranet services accessible on the extranet.