Chkrootkit – Come installare e schedulare rootkit scanner su Linux

chkrootkit

 

Chkrootkit è una raccolta di script e tools scritti in C che aiutanto gli amministratori di sistema a rilevare eventuali rootkit o LKM maligni installati sui sistemi Linux.

Per installare chrootkit su CentOS 6, basta usufruire del repository EPEL tramite yum.

1) Installare il repository EPEL

[[email protected] ~]# rpm -Uhv http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
Ripristino di http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
avvertimento: /var/tmp/rpm-tmp.T0Yctu: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparazione in corso...    ########################################### [100%]
   1:epel-release           ########################################### [100%]
[[email protected] ~]#

2) Installare chkrootkit

[[email protected] ~]# yum install chkrootkit

3) Eseguire scansione chrootkit

[[email protected] ~]# chkrootkit
ROOTDIR is `/'
Checking `amd'... not found
Checking `basename'... not infected
Checking `biff'... not found
Checking `chfn'... not infected
Checking `chsh'... not infected
Checking `cron'... not infected
Checking `crontab'... not infected
Checking `date'... not infected
Checking `du'... not infected
Checking `dirname'... not infected
Checking `echo'... not infected
Checking `egrep'... not infected
Checking `env'... not infected
Checking `find'... not infected
Checking `fingerd'... not found
Checking `gpm'... not found
Checking `grep'... not infected
Checking `hdparm'... not found
Checking `su'... not infected
Checking `ifconfig'... not infected
Checking `inetd'... not found
Checking `inetdconf'... not found
Checking `identd'... not found
Checking `init'... not infected
Checking `killall'... not infected
Checking `ldsopreload'... not infected
Checking `login'... not infected
Checking `ls'... not infected
Checking `lsof'... not found
Checking `mail'... not found
Checking `mingetty'... not infected
Checking `netstat'... not infected
Checking `named'... not found
Checking `passwd'... not infected
Checking `pidof'... not infected
Checking `pop2'... not found
Checking `pop3'... not found
Checking `ps'... not infected
Checking `pstree'... not infected
Checking `rpcinfo'... not found
Checking `rlogind'... not found
Checking `rshd'... not found
Checking `slogin'... not infected
Checking `sendmail'... not infected
Checking `sshd'... not infected
Checking `syslogd'... not tested
Checking `tar'... not infected
Checking `tcpd'... not infected
Checking `tcpdump'... not infected
Checking `top'... not infected
Checking `telnetd'... not found
Checking `timed'... not found
Checking `traceroute'... not found
Checking `vdir'... not infected
Checking `w'... not infected
Checking `write'... not infected
Checking `aliens'... no suspect files
Searching for sniffer's logs, it may take a while... nothing found
Searching for HiDrootkit's default dir... nothing found
Searching for t0rn's default files and dirs... nothing found
Searching for t0rn's v8 defaults... nothing found
Searching for Lion Worm default files and dirs... nothing found
Searching for RSHA's default files and dir... nothing found
Searching for RH-Sharpe's default files... nothing found
Searching for Ambient's rootkit (ark) default files and dirs... nothing found
Searching for suspicious files and dirs, it may take a while...
/usr/lib/.libcrypto.so.10.hmac /usr/lib/.libssl.so.10.hmac /usr/lib/.libcrypto.so.1.0.1e.hmac 
/usr/lib/.libssl.so.1.0.1e.hmac /lib/.libfipscheck.so.1.hmac /lib/.libfipscheck.so.1.1.0.hmac 
/lib/.libgcrypt.so.11.hmac
Searching for LPD Worm files and dirs... nothing found
Searching for Ramen Worm files and dirs... nothing found
Searching for Maniac files and dirs... nothing found
Searching for RK17 files and dirs... nothing found
Searching for Ducoci rootkit... nothing found
Searching for Adore Worm... nothing found
Searching for ShitC Worm... nothing found
Searching for Omega Worm... nothing found
Searching for Sadmind/IIS Worm... nothing found
Searching for MonKit... nothing found
Searching for Showtee... nothing found
Searching for OpticKit... nothing found
Searching for T.R.K... nothing found
Searching for Mithra... nothing found
Searching for LOC rootkit... nothing found
Searching for Romanian rootkit... nothing found
Searching for HKRK rootkit... nothing found
Searching for Suckit rootkit... nothing found
Searching for Volc rootkit... nothing found
Searching for Gold2 rootkit... nothing found
Searching for TC2 Worm default files and dirs... nothing found
Searching for Anonoying rootkit default files and dirs... nothing found
Searching for ZK rootkit default files and dirs... nothing found
Searching for ShKit rootkit default files and dirs... nothing found
Searching for AjaKit rootkit default files and dirs... nothing found
Searching for zaRwT rootkit default files and dirs... nothing found
Searching for Madalin rootkit default files... nothing found
Searching for Fu rootkit default files... nothing found
Searching for ESRK rootkit default files... nothing found
Searching for rootedoor... nothing found
Searching for ENYELKM rootkit default files... nothing found
Searching for common ssh-scanners default files... nothing found
Searching for anomalies in shell history files... nothing found
Checking `asp'... not infected
Checking `bindshell'... not infected
Checking `lkm'... chkproc: nothing detected
chkdirs: nothing detected
Checking `rexedcs'... not found
Checking `sniffer'... eth0: not promisc and no PF_PACKET sockets
Checking `w55808'... not infected
Checking `wted'... chkwtmp: nothing deleted
Checking `scalper'... not infected
Checking `slapper'... not infected
Checking `z2'... chklastlog: nothing deleted
Checking `chkutmp'... chkutmp: nothing deleted
Checking `OSX_RSPLUG'... not infected
[[email protected] ~]#

4) Stampare output chkrootkit solo in caso di rilevamento anomalie

[[email protected] ~]# chkrootkit| grep INFECTED

Se l’output sarà vuoto vuol dire che il programma non ha riscontrato nessuna anomalia.

5) Schedulazione scansione chkroorkit ed invio report tramite e-mail

Per schedulare una scansione automatica del proprio sistema Linux, basta creare uno semplice script da eseguire tramite il demone cron.

Ponendo il caso di voler effettuare una scansione settimanale, si deve creare il file “/etc/cron.weekly/chkrootkit” ed al suo interno scrivere:

#!/bin/sh

# Generatore data/ora stile: HH:mm dd/mm/YYYY
data=$(date "+%H:%M %d/%m/%Y")

# Indirizzo e-mail destinatario report
email="[email protected]"

# Esegui WPScan ed invia report per e-mail

chkrootkit | mail -s "Scansione automatica chkrootkit $data" $email

Per concludere la procedura, rendere eseguibile lo script:

[[email protected] ~]# chmod +x /etc/cron.weekly/chkrootkit