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SANS ISC: What is going on with port 3333? - Internet Security | DShield SANS ISC InfoSec Forums

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What is going on with port 3333?

We've seen a spike over the last day or so in reports of apparent scanning on TCP port 3333. I have serious doubts that anyone is actually looking for DEC Notes which is the registered IANA use for this port. While we're getting our own honeypots set up, I figured I'd ask our readers, do you have packets and/or any idea what is going on here? Please let us know in the comments or via our contact page. Thanx in advance.

Update: 2018-01-09 03:00 The original version of this diary inadvertantly said the traffic was UDP, the traffic that I am seeing in my logs at home is actually TCP. My apologies for the confusion.

Update: 2018-01-10 00:00 UTC The recurring theme in comments and email we've received suggests that some of the recent Monero miner malware samples are sending their results back to C2 servers on port 3333, so perhaps folks are trying to find and steal the illgotten cryptocurrency. I still haven't examined any traffic captured by our honeypots to confirm or refute that that is what they are looking for.


Jim Clausing, GIAC GSE #26
jclausing --at-- isc [dot] sans (dot) edu


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402 Posts
ISC Handler
A lot of mining pools are configured on 3333 for their low hash levels (e.g. Might be someone mapping pools?

2 Posts
It's the stratum protocol for Monero mining traffic. CVE-2017-10271 had PoC exploit code released recently. Around the Jan 1st the exploit was observed being used to push Monero miners to servers. Since then there has been a large uptick compromised servers.

Here are some of the mining pools / ports observed from samples I've seen.
I am seeing activity on tcp port 3333 as well from a few different sources. Main Source IPs are and I don't have any other info.
This could also be some type of search for the Claymore miner software used in mining. The application opens port tcp/3333 for read only monitoring. Possibly a vulnerability exists in the code that allows configuration changes.;topicseen#msg14501372

1 Posts
If the owner configures it with a password you can remotely write arbitrary files to the filesystem (assuming you know/guess the password). If you write a script to reboot.bat or, you can get the software to run it via another API endpoint.

2 Posts

this is what we see hitting this port from 01/16 - 01/22

2 Posts
I'm with the theory that it is #mining related. I also noted that 3333 is the default port of the Gophish admin server.

66 Posts

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