The Network Security Lab at 360 provided evidence that the Mirai botnet has a built-in domain generator algorithm (DGA) feature. In this blog, we share some of what we learned about frequent traffic patterns of Mirai DGA domains.
- Mirai DGA domains may see up to 10K queries per hour.
- A frequent pattern is seen where Mirai DGA domains initially appear within a day, then re-emerge in a sustained period of query volume.
- We began to see Mirai DGA query volumes spike after December 2 (although the
.pwvariant appears to have shown up a couple days earlier).
- On December 8, Mirai hard-coded C2 domains displayed a coordinated spike in query volume.
A quick note: these conclusions were generated from our unique traffic and may be different from conclusions drawn by others performing a similar analysis.
CLIENT IP – DOMAIN GRAPH
To find these DGA domains, we pivoted off known hardcoded C2 domains used by Mirai:
In addition, we found another
tr069 with a different TLD:
Leveraging our distributed bipartite Client IP-Domain graph we found client traffic which overlapped these hard-coded domains with wordless domains – the DGA domains.
From mining this graph, we were able to find DGA domains with highly similar traffic patterns.
In fact, in a later analysis we found a majority of these domains (at one time) hosted on the IP:
18.104.22.168 which we first saw on December 5 at 05:54 UTC.
Here’s a sample of 4 top-level domains (TLDs) with what appear to be Mirai associated domains –
pw. More specifically, we will discuss query volumes from this sample of domains:
QUERY VOLUME VERSUS CLIENT VOUME
The query volume is a raw count of the total number of processed DNS requests for a domain, which may include repeat visitors. In this analysis we group queries by hour. This is in contrast to a related count, the client volume, which tracks unique visitors to a domain – similarly, grouped by hour.
For example, here’s an example of the unique number of clients querying the Mirai C2 domain
zugzwang.me over the last 7 days in the USA:
FIGURE 1: Unique USA client volume querying
zugzwang.me in the last 7 days.
Similarly, here’s the USA client volume to
tr069.pw in the last 7 days:
FIGURE 2:Unique USA client volume querying
tr069.pw in the last 7 days.
Notice, the number of clients within the USA querying these domains varies: one domain had a maximum within one hour around 15 clients, while the other 2 clients.
In contrast, the plots below show the total query volume for individual domains grouped by hour.
For reference, you might wish to know the traffic patterns of the C2 domains mentioned above. The query volumes are taken from aggregating all the queries processed in our resolvers around the world.
It appears that on December 8, Mirai hard-coded C2 domains displayed a coordinated spike in query volume. Next, we’ll look at query volumes from a sample of Mirai DGA domains.
The first TLD we look at is
tech. We show 5 different domains with what appears to be 4 different traffic patterns.
The second TLD we look at is
support. We show 4 different domains with what appears to be 2 different traffic patterns. We note, these traffic patterns overlap with those of
The third TLD we look at is
online. We show 2 different domains, each with a different traffic pattern. We note, these traffic patterns overlap with those of
tech & support to some extent.
The last TLD we look at is
pw. We show 4 different domains, each with a different traffic pattern. We note, these traffic patterns appear like some of those of
We point out that
srrys.pw appears earlier than December 2, 2016 and
binpt.pw has more sustained traffic than previously discussed domains.
We also found a couple other domains which may interest other researchers. Since these domains don’t appear to be generated by the same DGA, they don’t appear above. The two other domains are: