If your network scans have been showing increased attempts to find an open TCP port 3333 -- you're not alone.
SANS ISC, Qihoo 360 Netlab and GreyNoise Intelligence report that someone has been looking for this port to be active for the last week or so. Netlab was the first to tweet the activity.
Do you see port 3333 scan traffic going up? Satori botnet is scanning it now, see our Scanmon trend https://t.co/TyrL4ryt6J, and try a dns lookup for one of the control domain it is using now, dig any https://t.co/DM4JTtXFo3, I personally like yesterday's TXT result more pic.twitter.com/xXUjwjZNdD— 360 Netlab (@360Netlab) May 11, 2018
Port 3333 is routinely used for cryptominer's remote management.
A day later, GreyNoise confirmed the activity in a tweet and deduced it was associated with the "Claymore" dual Ethereum/Decred cryptocurrency miner. Port 3333 is the default management port for this miner.
GreyNoise observed a large spike of TCP port 3333 scan traffic today. This is the default port for the "Claymore" dual Ethereum/Decred cryptocurrency miner. pic.twitter.com/5g6vVbPLNq— GreyNoise Intelligence (@GreyNoiseIO) May 11, 2018
The researchers there also found that, "Once the attacker identifies a server running the Claymore software they push instructions to reconfigure the device to join the 'dwarfpool' mining pool and use the attacker's ETH wallet."
Interestingly, researchers found that the scans were originating from Mexico, and matched those IP addresses with those that had been identified as being GPON routers affected by different compromises -- CVE-2018-10561 and CVE-2018-10562. These are about 17,000 independent IP addresses, mainly from Uninet SA de CV, telmex.com, located in Mexico.
The compromise had been weaponized and the affected home routers were under attack by five different botnets. GreyNoise made the call that it was the Satori botnet doing the malicious scans and the hijack to crypto mining.
Netlab confirmed the call the next day. While this variant was changed from the original Satori, there were some key elements -- key strings, domain name TXT information, email addresses -- that allowed an identification.
Looking at the ETH wallet, Netlab finds: "Satori received a total of approximately $200 in the current 6-day operation."
The re-emergence of the Satori botnet as a malicious force shows how easily attacked hardware like the GPON routers can have serious consequences.
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— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.