Cyber Security: Detect and remove trojans in a Linux operating system

Jika kerentanan terdeteksi di sistem operasi Linux Anda tetapi Anda tidak mengambil tindakan pencegahan, trojan dapat dimasukkan ke dalam sistem Anda. Anda harus menghapus trojan dari sistem Anda sesegera mungkin. Selain itu, Anda harus memperkuat keamanan sistem Anda dengan menggunakan beberapa metode. Misalnya, Anda dapat menginstal patch keamanan, mengontrol izin sistem, mengaudit operasi, dan menganalisis log.

Step 1: Gunakan Use Security Center untuk detect trojan

Masuk ke Security Center console untuk menangani peringatan dan menghapus trojan yang terdeteksi sesegera mungkin. Untuk informasi selengkapnya, lihat Melihat dan menangani peristiwa peringatan.

Perbaiki kerentanan sedini mungkin untuk memperkuat keamanan sistem Anda. Untuk informasi selengkapnya, lihat Melihat dan menangani kerentanan perangkat lunak Linux.

Step 2: Query detail attack

Run Command	Description
last
lastlog	cek waktu masuk terakhir dan akun masuk. Kemudian, lock akun yang tidak normal
grep -i Accepted /var/log/secure	Cek IP address user yang masuk dari remote
/var/spool/cron/
/etc/cron.hourly
/etc/crontab	cek cron job
find / -ctime 1	cek file terakhir yang di update, ini salah satu cara mencek trojan
sudo more /etc/passwd
sudo more /etc/shadow	cek ada user yang aneh atau tidak
sudo ls /tmp
sudo ls /vat/tmp
sudo ls /dev/shm	temporary directory dengan permission 1777 biasanya dipakai upload trojan
service --status-all	cek exception pada service yang running.
grep :on	cek apakah ada exception di service yang start automatis.
Run the ls -lt /etc/init.d/	cek head command apakah ada abnormal startup scripts.
	Cek apakah ada exception di log services seperti Tomcat atau NGINX, yang port service-nya bisa di akses dari Internet.

Step 3: Run commonly used commands to detect trojans

Caption text

Command	Desci[topm
ps or top	You can run these commands to query the running processes and system resources that are occupied by these processes. This way, you can identify abnormal processes.
pstree	You can run this command to visualize the relationship among processes in a treemap.
lsof	You can run this command to query the files opened by a process, the files or directories occupied by a process, the process that opens a specific port, and all the open ports in the system.
netstat	You can run this command to query all the ports monitored by the system, network connection status, and the IP addresses from which excessive connections are established.
iftop	You can run this command to monitor the network traffic forwarded over TCP connections in real time. This way, you can distinguish between and sort inbound and outbound traffic, and identify the IP addresses that have abnormal network traffic.
nethogs	You can run this command to monitor the network traffic generated by each process and sort the processes by traffic volume in descending order. This way, you can identify abnormal processes with unusual large traffic.
strace	You can run this command to trace system calls executed by a specific process. This way, you can analyze the running status of trojans.
strings	You can run this command to obtain the strings of printable characters in files. Then, you can use the strings to analyze trojans.