Severity

Medium

Category

Cyber Crime

Analysis Summary

Linux Platform is being targeted by a new malware strain that installs the XMR-Stak Cryptonight cryptocurrency miner. Additionally, it also searches for other Linux malware and coin miners already present on the compromised machine, and kills them to maximize its own cryptocurrency mining.

This KORKERDS variant downloads the universal Stratum XMR-Stak pool miner which uses the system’s CPU or GPU to mine Cryptonight currencies. Following activities have also been observed:

Function B kills previously installed malware, coin miners, and all related services referenced to an accompanying malware. It also creates new directories, files, and stops processes with connections to identified IP addresses. Function D downloads the coin miner binary from hxxp://yxarsh[.]shop/64 and runs it. Function C downloads a script from hxxp://yxarsh[.]shop/0, saves it to /usr/local/bin/dns file, and creates a new crontab to call this script at 1 a.m. It also downloads hxxp://yxarsh[.]shop/1.jpg and puts it in different crontabs.

The malware will also make sure to clear system logs to erase its traces, and will also achieve persistence avoiding removal after reboots or deletion with the help of the implanted crontab files. The second stage of the infection originates from multiple IP cameras and web services via the TCP port 8161, from domains where the attackers have stored the crontab file which launches the main stage of the malware attack.

Impact

Cryptocurrency mining

Other unspecified impact is also possible

Affected Products

Linux

Indicators of Compromise

URLs

drnfbu[.]xyz:26750

hxxp://yxarsh.shop

hxxp://yxarsh.shop/0

hxxp://yxarsh.shop/1.jpg

hxxp://yxarsh.shop/64

hxxp://yxarsh.shop/86

hxxps://pastebin.com/u/SYSTEAM

Filename

/opt/yilu/mservice

/opt/yilu/work/xig/xig

/opt/yilu/work/xige/xige

/tmp/thisxxs

/usr/bin/.sshd

/usr/bin/bsd-port/getty

/usr/local/bin/dns

/etc/cron.hourly/oanacroner

/etc/cron.daily/oanacroner

/etc/cron.monthly/oanacroner

Erased:

/var/spool/mail/root

/var/log/wtmp

/var/log/secure

/var/log/cron

Malware Hash (MD5/SHA1/SH256)

d9390bbbc6e399a388ac6ed601db4406eeb708f3893a40f88346ee002398955c

2f7ff54b631dd0af3a3d44f9f916dbde5b30cdbd2ad2a5a049bc8f2d38ae2ab6

Remediation

Block the threat indicators at their respective controls.

Keep all Linux systems up-to-date with the latest patches against all vulnerabilities, as Linux is seen to be targeted by many threat actors.