197. Hunting for C2 Request Patterns

Hello everyone!

Let's keep talking about C2 communications. And this time we'll look at an activity cluster we track as Rainbow Hyena (it's also known as Head Mare).

Let's look at the following part of the report:

After collecting initial information about the compromised system, the backdoor establishes a connection with the C2 server. The communication is carried out over HTTP, using GET and POST requests. The malware generates a GET request and accesses a URL in the following format:

91.239.148[.]21/poll?id=&hostname=&domain=

As you can see, there's a certain pattern we can use for hunting even if we don't know the IP address of the server.

Let's look at another example. It the same group, but the pattern is different:

hxxp://195.58.54[.]39:80/connect

hxxp://195.58.54[.]39/check

hxxp://195.58.54[.]39/command

hxxp://195.58.54[.]39/init

And this is another thing you should notice, document and use for threat hunting, both internal and external.

See you tomorrow!

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