High Cpu utilization on vsftpd

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thorin06
Posts: 2
Joined: 2019/09/11 15:44:21

High Cpu utilization on vsftpd

Post by thorin06 » 2019/09/11 15:53:34

Hello,

I got an issue with one of my CentOS box. It has a high cpu utilization on vsftpd, can someone shed some light why is the vsftpd causes the high cpu load? (multiple processess running and need fine-tuning?)

[root@xxxxxx ~]# cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)


PID SYSCPU USRCPU VGROW RGROW RDDSK WRDSK RUID EUID ST EXC THR S CPUNR CPU CMD 1/407
19802 0.38s 2.17s 0K 0K - - ggdlx02u - NE 0 0 E - 26% <vsftpd>
26858 0.26s 1.51s 0K 0K - - ggdlx02u - NE 0 0 E - 18% <vsftpd>
28400 0.20s 1.17s 74576K 1328K 0K 0K ggdlx02u ggdlx02u N- - 1 R 1 14% vsftpd
1837 0.01s 1.29s 0K 0K 0K 0K root root -- - 1 S 2 13% rngd
22695 0.20s 1.10s 0K 0K - - ggdlx02u - NE 0 0 E - 13% <vsftpd>



1 [#####################################*************100.0%] Tasks: 4830, 681 thr; 4 running
2 [####################################**************100.0%] Load average: 55.38 45.77 42.57
3 [##########################************************100.0%] Uptime: 24 days, 15:17:04
4 [#######################################***********100.0%]
Mem[|||||||||||||||||||||||||||||||||||||||||||||25.9G/31.3G]
Swp[||||||||| 604M/4.00G]

PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command
2622 ggdlx02uc 20 0 74576 1328 860 R 28.8 0.0 0:00.70 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
32008 ggdlx02uc 20 0 90592 1416 880 R 28.2 0.0 0:01.29 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
5121 ggdlx02uc 20 0 90592 1424 888 R 16.9 0.0 0:00.30 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
1837 root 20 0 90500 1596 1500 R 13.0 0.0 16h13:06 /sbin/rngd -f
5748 ggdlx02uc 20 0 74576 1328 860 R 7.9 0.0 0:00.14 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
5757 ggdlx02uc 20 0 74580 1324 860 R 7.9 0.0 0:00.14 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
17605 root 20 0 123M 6300 1496 R 7.3 0.0 0:01.09 htop
26222 ggdlx02td 20 0 134M 18680 1052 S 1.7 0.1 0:03.16 find /local/home/ggdlx02tdba/comms/outtray/2019 /local/home/g

[root@xxxxxx ~]# cat /etc/vsftpd/vsftpd.conf
# Example config file /etc/vsftpd/vsftpd.conf
#
# The default compiled in settings are fairly paranoid. This sample file
# loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd.conf.5 for all compiled in defaults.
#
# READ THIS: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's
# capabilities.
#
# Allow anonymous FTP? (Beware - allowed by default if you comment this out).
anonymous_enable=YES
#
# Uncomment this to allow local users to log in.
# When SELinux is enforcing check for SE bool ftp_home_dir
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# if your users expect that (022 is used by most other ftpd's)
local_umask=022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# has an effect if the above global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
# When SELinux is enforcing check for SE bool allow_ftpd_anon_write, allow_ftpd_full_access
#anon_upload_enable=YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# Activate logging of uploads/downloads.
xferlog_enable=YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES
#
# If you want, you can arrange for uploaded anonymous files to be owned by
# a different user. Note! Using "root" for uploaded files is not
# recommended!
#chown_uploads=YES
#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/xferlog
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
xferlog_std_format=YES
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120
#
# It is recommended that you define on your system a unique user which the
# ftp server can use as a totally isolated and unprivileged user.
#nopriv_user=ftpsecure
#
# Enable this and the server will recognise asynchronous ABOR requests. Not
# recommended for security (the code is non-trivial). Not enabling it,
# however, may confuse older FTP clients.
#async_abor_enable=YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# the request. Turn on the below options to have the server actually do ASCII
# mangling on files when in ASCII mode. The vsftpd.conf(5) man page explains
# the behaviour when these options are disabled.
# Beware that on some FTP servers, ASCII support allows a denial of service
# attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd
# predicted this attack and has always been safe, reporting the size of the
# raw file.
# ASCII mangling is a horrible feature of the protocol.
#ascii_upload_enable=YES
#ascii_download_enable=YES
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# useful for combatting certain DoS attacks.
#deny_email_enable=YES
# (default follows)
#banned_email_file=/etc/vsftpd/banned_emails
#
# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
# (Warning! chroot'ing can be very dangerous. If using chroot, make sure that
# the user does not have write access to the top level directory within the
# chroot)
#chroot_local_user=YES
#chroot_list_enable=YES
# (default follows)
#chroot_list_file=/etc/vsftpd/chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled by
# default to avoid remote users being able to cause excessive I/O on large
# sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# the presence of the "-R" option, so there is a strong case for enabling it.
#ls_recurse_enable=YES
#
# When "listen" directive is enabled, vsftpd runs in standalone mode and
# listens on IPv4 sockets. This directive cannot be used in conjunction
# with the listen_ipv6 directive.
listen=NO
#
# This directive enables listening on IPv6 sockets. By default, listening
# on the IPv6 "any" address (::) will accept connections from both IPv6
# and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6
# sockets. If you want that (perhaps because you want to listen on specific
# addresses) then you must run two copies of vsftpd with two configuration
# files.
# Make sure, that one of the listen options is commented !!
listen_ipv6=YES

pam_service_name=vsftpd
userlist_enable=YES
tcp_wrappers=YES

Can someone help me out to make a thorough investigation on this issue. Many thanks

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TrevorH
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Posts: 26621
Joined: 2009/09/24 10:40:56
Location: Brighton, UK

Re: High Cpu utilization on vsftpd

Post by TrevorH » 2019/09/11 16:05:29

Start by reading the logs it writes and see if someone is hacking into it by brute force attack.
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thorin06
Posts: 2
Joined: 2019/09/11 15:44:21

Re: High Cpu utilization on vsftpd

Post by thorin06 » 2019/09/11 16:33:52

i checked the logs, no malicious events. Transaction is coming from internal server. Corporate firewall is enabled.

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