A new Internet Relay Channel (IRC) bot, which is built with the help of the Perl language-based Shellbot, is targeting Windows-based environments, along with Ubuntu Linux and even Android devices, according to a blog post from the Trend Micro Cyber Safety Solutions Team.
The researchers stuck the name of "Outlaw" on the group behind this bot. The name is a translation from Romanian word for the tool -- haiduc -- that the threat actors use.
The group has spread the bot through the use of a common command injection vulnerability on Internet of Things (IoT) devices, as well as Linux servers. Trend reports that the IRC channel used for control of the bot had 142 infected hosts as members.
While Trend's honeypots found the existence of the bot, they also found that the Outlaw group had compromised an File Transfer Protocol (FTP) server of a Japanese art institution, along with a Bangladeshi government site. The Bangladeshi attack took advantage of a vulnerability on a Dovecot mail server.
The botnet itself, which has been available on GitHub, had previously been spread through the Shellshock vulnerability. Trend's research found that it is now spreading through previously brute-forced or compromised hosts.
Once installed, the bot is in resident. The connection to the control IRC channel occurs immediately after infection and is persistent. If connectivity is lost, the bot will immediately reconnect once an Internet connection returns.
The administrator of the IRC channel can send commands to the backdoor-infected host. Trend discovered that the possibilities included commands to perform a port scan, launching distributed denial of service (DDoS) attacks, downloading a file, getting information about other machines on the network, sending the operating system information, as well as a list of certain running processes that are present on the command-and-control (C&C) server.
DDoS-related activity affects User Data Protocol (UDP), TCP and HTTP traffic, according to Trend.
Researchers also found that the infected IRC hosts showed base C&C connection in the form of PING/PONG traffic. The IRC needs this sort of challenge and response to keep the connection open. In addition, the IRC bot occasionally asks for updates, as well as providing some host information.
That information might include suspicious crontab-like records, along with the process identifier (PID) of the sd-pam process of the user who was running the IRC bot on the system.
Using an IRC bot isn't a novel threat, but it may be able to sneak in under the radar of many security measures. Trend suggests enterprise should mitigate the threat by setting up the SSH login process properly, which means not leaving it open to public networks unless it is necessary for your infrastructure.
Monitoring non-DNS traffic coming to and from port 53 is also highly recommended.
Restricting the use of FTP as much as possible is also desirable. This is the method that is usually used for loading the exploit files to the victim systems.
Measures like these will help to prevent outlaws from roping and stealing your cattle.
— 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.