In one of the last pentests we’ve found an epmd (Erlang port mapper daemon) listening on a target system (tcp/4369). It is used to coordinate distributed erlang instances, but also can lead to a RCE, given one knows the so called “authentication cookie”. Usually, this cookie is located in ~/.erlang.cookie and is generated by erlang at the first start. If not modified or set manually it is a random string [A:Z] with a length of 20 characters. If an attacker gains this cookie, a RCE is quite easy – as I like to describe below.
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