The other day while reviewing my fireplot graphs, I noticed (yet) another portscan. They’re not unusual. This one took around four and a half hour to complete, and covered a lot of TCP ports on one IPv4 address. That’s not unusual either. The curved graph shown below is caused by the plot’s logarithmic Y axis, […]
Seems a new bot, possibly a strain of Mirai, is in the wild, targeting TCP port 37777. The last 24 hours I’ve seen close to 200 different IP addresses trying to connect to this port. DShield is also registering an increase. At the moment I can only guess what kind of product they’re probing for, […]
Those familiar with port scanning tools (like nmap), have probably heard of the Xmas scan option. This scanning strategy sets some unusual TCP flags, as the man page describes it: Sets the FIN, PSH, and URG flags, lighting the packet up like a Christmas tree. Yesterday, my firewall was systematically scanned with a combination of […]
Since yesterday I’ve registered a significant increase in probes for TCP port 7547. Over the last 12 hours, more than 1000 different IP addresses have tried to contact one of my networks. 1000 probes is of course no big deal, but the port that’s suddenly become of interest can be. The image below shows the […]
For some time now, I’ve been graphing all unsolicited network traffic destined for my network. For instance, it’s quite useful for detecting slow scans, which will show up as the diagonally aligned green scatter points in this plot (click to enlarge). Other scans and probes often happen faster, when the attacker isn’t much concerned about […]
Building a toolbox around threat intelligence can be done with freely available tools. Shared information about malicious behaviour allows you to detect and sometimes prevent activity from – and to – Internet resources that could compromise your systems’ security. I’ve already described how to use lists of malicious domain names in a BIND RPZ (Response […]
Previously I’ve written about visualizing firewall activity. Revitalizing a fireplot graphing tool gives a nice day-to-day overview, but after being reminded of Logstalgia in this Imgur post I wanted to give live visualization a shot. Logstalgia is a neat tool for visualizing activity, by feeding it log files or live feeds. It’s originally designed for […]