Researchers discovered the threat after a sample of the malware targeted one Akamai honeypot. The attackers dropped a PHP malware sample through a backdoor linked to a WordPress plugin called Download-monitor, which was installed after the honeypot was accessed.
These crypto mining malware attacks, SIRT honeypots were infected with PHP malware that arrived via a backdoored addition to a WordPress plugin named download-monitor. Once after installed the honeypot’s weak WordPress admin credentials had been guessed. A 3MB UPX packed Golang binary was also downloaded to /temp. Upon examination, it was clear the malware had some decryption functionality and an encrypted file stored in another directory.
The attackers installed several web shells to carry out malicious activities such as uploading stolen files to a remote server controlled by the attackers. The analysis of the binary revealed the presence of a port scanner that is used to target randomly generated IP addresses and checking for ports to target with known exploits.
To achieve persistence, the malware first chooses a legitimate-looking system path from a small list of locations on a disk where you’d likely find system binaries, then it generates a random six-character filename, and uses these two pieces to copy itself into the new location on the disk and deletes itself. The malicious code injects/updates a Crontab entry that will trigger the execution of the above binary. Keeping an eye on system resource consumption, odd/unexpected running processes, suspicious artifacts (files, crontab entries, SSH keys, etc.), and suspicious access log entries, will be the prime source of detections.