Hi Guys,
Have you encountered with DDoS Trojan attack? Hopefully, yes!
It's a familiar issue to all Sys-Admins, when we work on DDoS attack. Normally, the top command shows a suspicious process with a random name like, Xdrgwdjd, jjiiyaykzg etc or some system commands like ls, ifconfig, pwd, ping, awk, telnet etc.
When we kill that task another random process is being generated immediately.
Steps :
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1) List the files under hourly cron. If you can see any .sh file, please open it.
root@vps-# ls -la /etc/cron.hourly/
++++++++++
CT-24007-bash-4.1# ls /etc/cron.hourly/
freshclam gcc.sh
CT-24007-bash-4.1#
++++++++++
2) If the .sh file is showing similar data as shown below, then it's a Virus program!!
root@vps-# cat /etc/cron.hourly/gcc.sh
++++++++++
cat /etc/cron.hourly/gcc.sh
#! / Bin / sh
PATH = / bin: / sbin: / usr / bin: / usr / sbin: / usr / local / bin: / usr / local / sbin: / usr / X11R6 / bin
for i in `cat / proc / net / dev | grep: | awk -F: {'print $ 1'}`; do ifconfig $ i up & done
cp /lib/libudev.so /lib/libudev.so.6
/lib/libudev.so.6
++++++++++
3) Now, please don't be hurry! Stay calm and easy
# Do not delete gcc.sh or do not remove the crontab. If you do delete or remove it, then another process will generate immediately.
# You can either remove the culprit script or disable it. [ I prefer to disable it to show the proof to the customer ]
root@vps-# rm -f /etc/cron.hourly/gcc.sh;
OR
root@vps- # chmod 0 /etc/cron.hourly/gcc.sh; chattr +ia /etc/cron.hourly/gcc.sh; chattr + i /etc/crontab
4) Use top command to view virus or malicious file ( Eg :"mtyxkeaofa" ) PID is 16621, do not directly kill the program, otherwise it will again produce, but to stop its operation use the below command.
----------------------------------
root@vps- # kill -STOP 16621
# Delete files within /etc/init.d. or disable it [ I prefer to disable it to show the proof to the customer ]
root@vps-# find /etc -name '* mtyxkeaofa *' | xargs rm -f
OR
chmod 0 /usr/bin/mtyxkeaofa;
chmod 0 /etc/init.d/mtyxkeaofa;
chattr +ia /usr/bin/mtyxkeaofa;
chattr +ia /etc/init.d/mtyxkeaofa;
----------------------------------
6) Delete /usr/bin inside archives.
root@vps-# rm -f /usr/bin/mtyxkeaofa;
7) Check /usr/bin archives recent changes, the virus can also be deleted if the other suspect is the same directory.
root@vps-# ls -lt /usr/bin | head
Now kill the malicious program, it will not produce.
root@vps-# pkill mtyxkeaofa
9) Remove the virus body.
root@vps-# rm -f /lib/libudev.so
This trojan is also know as Chinese Chicken Multiplatform DoS botnets Trojan, Unix - Trojan.DDoS_XOR-1, Embedded rootkit,
Note :~ If you are unable to find .sh file, you may please install ClamAV, RKHunter and check logs/report to find the suspicious/malicious
That's it
