Cómo buscar rootkits, puertas traseras y exploits usando 'Rootkit Hunter' en Linux
Chicos, si son lectores habituales de linux-console.net, notarán que este es nuestro tercer artículo sobre herramientas de seguridad. En nuestros dos artículos anteriores, le brindamos toda la orientación sobre cómo proteger Apache y sistemas Linux contra malware, DOS, y ataques DDOS usando mod_security y mod_evasive y LMD (Linux Malware Detect).
Nuevamente estamos aquí para presentarles una nueva herramienta de seguridad llamada Rkhunter (Rootkit Hunter). Este artículo le guiará sobre cómo instalar y configurar RKH (RootKit Hunter) en sistemas Linux utilizando el código fuente.
¿Qué es Rkhunter?
Rkhunter (Rootkit Hunter) es una herramienta de análisis de código abierto basada en Unix/Linux para sistemas Linux publicada bajo GPL que analiza puertas traseras, rootkits y exploits locales en sus sistemas.
Analiza archivos ocultos, permisos incorrectos establecidos en archivos binarios, cadenas sospechosas en el kernel, etc. Para saber más sobre Rkhunter y sus características, visite http://rkhunter.sourceforge.net/.
Instale Rootkit Hunter Scanner en sistemas Linux
Paso 1: Descargar Rkhunter
Primero, descargue la última versión estable de la herramienta Rkhunter yendo a http://rkhunter.sourceforge.net/ o use el siguiente comando Wget para descargarla en sus sistemas. .
cd /tmp
wget http://downloads.sourceforge.net/project/rkhunter/rkhunter/1.4.6/rkhunter-1.4.6.tar.gz
Paso 2: instalar Rkhunter
Una vez que haya descargado la última versión, ejecute los siguientes comandos como usuario root para instalarla.
tar -xvf rkhunter-1.4.6.tar.gz
cd rkhunter-1.4.6
./installer.sh --layout default --install
Salida de muestra
Checking system for:
Rootkit Hunter installer files: found
A web file download command: wget found
Starting installation:
Checking installation directory "/usr/local": it exists and is writable.
Checking installation directories:
Directory /usr/local/share/doc/rkhunter-1.4.2: creating: OK
Directory /usr/local/share/man/man8: exists and is writable.
Directory /etc: exists and is writable.
Directory /usr/local/bin: exists and is writable.
Directory /usr/local/lib64: exists and is writable.
Directory /var/lib: exists and is writable.
Directory /usr/local/lib64/rkhunter/scripts: creating: OK
Directory /var/lib/rkhunter/db: creating: OK
Directory /var/lib/rkhunter/tmp: creating: OK
Directory /var/lib/rkhunter/db/i18n: creating: OK
Directory /var/lib/rkhunter/db/signatures: creating: OK
Installing check_modules.pl: OK
Installing filehashsha.pl: OK
Installing stat.pl: OK
Installing readlink.sh: OK
Installing backdoorports.dat: OK
Installing mirrors.dat: OK
Installing programs_bad.dat: OK
Installing suspscan.dat: OK
Installing rkhunter.8: OK
Installing ACKNOWLEDGMENTS: OK
Installing CHANGELOG: OK
Installing FAQ: OK
Installing LICENSE: OK
Installing README: OK
Installing language support files: OK
Installing ClamAV signatures: OK
Installing rkhunter: OK
Installing rkhunter.conf: OK
Installation complete
Paso 3: Actualizar Rkhunter
Ejecute el actualizador RKH para completar las propiedades de la base de datos ejecutando el siguiente comando.
/usr/local/bin/rkhunter --update
/usr/local/bin/rkhunter --propupd
Salida de muestra
[ Rootkit Hunter version 1.4.6 ]
Checking rkhunter data files...
Checking file mirrors.dat [ Updated ]
Checking file programs_bad.dat [ No update ]
Checking file backdoorports.dat [ No update ]
Checking file suspscan.dat [ No update ]
Checking file i18n/cn [ No update ]
Checking file i18n/de [ No update ]
Checking file i18n/en [ No update ]
Checking file i18n/tr [ No update ]
Checking file i18n/tr.utf8 [ No update ]
Checking file i18n/zh [ No update ]
Checking file i18n/zh.utf8 [ No update ]
Checking file i18n/ja [ No update ]
File created: searched for 177 files, found 131, missing hashes 1
Paso 4: configurar alertas de correo electrónico y cronjob
Cree un archivo llamado rkhunter.sh en /etc/cron.daily/, que luego escanea su sistema de archivos todos los días y envía notificaciones por correo electrónico. a su identificación de correo electrónico. Crea el siguiente archivo con la ayuda de tu editor favorito.
vi /etc/cron.daily/rkhunter.sh
Agregue las siguientes líneas de código y reemplace “YourServerNameHere” con su “Nombre del servidor” y “[email ” con su “ID de correo electrónico“.
#!/bin/sh
(
/usr/local/bin/rkhunter --versioncheck
/usr/local/bin/rkhunter --update
/usr/local/bin/rkhunter --cronjob --report-warnings-only
) | /bin/mail -s 'rkhunter Daily Run (PutYourServerNameHere)' [email
Establezca el permiso de ejecución en el archivo.
chmod 755 /etc/cron.daily/rkhunter.sh
Paso 5: escaneo manual y uso
Para escanear todo el sistema de archivos, ejecute Rkhunter como usuario root.
rkhunter --check
Salida de muestra
[ Rootkit Hunter version 1.4.6 ]
Checking system commands...
Performing 'strings' command checks
Checking 'strings' command [ OK ]
Performing 'shared libraries' checks
Checking for preloading variables [ None found ]
Checking for preloaded libraries [ None found ]
Checking LD_LIBRARY_PATH variable [ Not found ]
Performing file properties checks
Checking for prerequisites [ OK ]
/usr/local/bin/rkhunter [ OK ]
/usr/sbin/adduser [ OK ]
/usr/sbin/chkconfig [ OK ]
/usr/sbin/chroot [ OK ]
/usr/sbin/depmod [ OK ]
/usr/sbin/fsck [ OK ]
/usr/sbin/fuser [ OK ]
/usr/sbin/groupadd [ OK ]
/usr/sbin/groupdel [ OK ]
/usr/sbin/groupmod [ OK ]
/usr/sbin/grpck [ OK ]
/usr/sbin/ifconfig [ OK ]
/usr/sbin/ifdown [ Warning ]
/usr/sbin/ifup [ Warning ]
/usr/sbin/init [ OK ]
/usr/sbin/insmod [ OK ]
/usr/sbin/ip [ OK ]
/usr/sbin/lsmod [ OK ]
/usr/sbin/lsof [ OK ]
/usr/sbin/modinfo [ OK ]
/usr/sbin/modprobe [ OK ]
/usr/sbin/nologin [ OK ]
/usr/sbin/pwck [ OK ]
/usr/sbin/rmmod [ OK ]
/usr/sbin/route [ OK ]
/usr/sbin/rsyslogd [ OK ]
/usr/sbin/runlevel [ OK ]
/usr/sbin/sestatus [ OK ]
/usr/sbin/sshd [ OK ]
/usr/sbin/sulogin [ OK ]
/usr/sbin/sysctl [ OK ]
/usr/sbin/tcpd [ OK ]
/usr/sbin/useradd [ OK ]
/usr/sbin/userdel [ OK ]
/usr/sbin/usermod [ OK ]
....
[Press to continue]
Checking for rootkits...
Performing check of known rootkit files and directories
55808 Trojan - Variant A [ Not found ]
ADM Worm [ Not found ]
AjaKit Rootkit [ Not found ]
Adore Rootkit [ Not found ]
aPa Kit [ Not found ]
.....
[Press to continue]
Performing additional rootkit checks
Suckit Rookit additional checks [ OK ]
Checking for possible rootkit files and directories [ None found ]
Checking for possible rootkit strings [ None found ]
....
[Press to continue]
Checking the network...
Performing checks on the network ports
Checking for backdoor ports [ None found ]
....
Performing system configuration file checks
Checking for an SSH configuration file [ Found ]
Checking if SSH root access is allowed [ Warning ]
Checking if SSH protocol v1 is allowed [ Warning ]
Checking for a running system logging daemon [ Found ]
Checking for a system logging configuration file [ Found ]
Checking if syslog remote logging is allowed [ Not allowed ]
...
System checks summary
=====================
File properties checks...
Files checked: 137
Suspect files: 6
Rootkit checks...
Rootkits checked : 383
Possible rootkits: 0
Applications checks...
Applications checked: 5
Suspect applications: 2
The system checks took: 5 minutes and 38 seconds
All results have been written to the log file: /var/log/rkhunter.log
One or more warnings have been found while checking the system.
Please check the log file (/var/log/rkhunter.log)
El comando anterior genera un archivo de registro en /var/log/rkhunter.log con los resultados de la comprobación realizada por Rkhunter.
cat /var/log/rkhunter.log
Salida de muestra
[11:21:04] Running Rootkit Hunter version 1.4.6 on tecmint
[11:21:04]
[11:21:04] Info: Start date is Mon Dec 21 11:21:04 AM IST 2020
[11:21:04]
[11:21:04] Checking configuration file and command-line options...
[11:21:04] Info: Detected operating system is 'Linux'
[11:21:04] Info: Found O/S name: Fedora release 33 (Thirty Three)
[11:21:04] Info: Command line is /usr/local/bin/rkhunter --check
[11:21:04] Info: Environment shell is /bin/bash; rkhunter is using bash
[11:21:04] Info: Using configuration file '/etc/rkhunter.conf'
[11:21:04] Info: Installation directory is '/usr/local'
[11:21:04] Info: Using language 'en'
[11:21:04] Info: Using '/var/lib/rkhunter/db' as the database directory
[11:21:04] Info: Using '/usr/local/lib64/rkhunter/scripts' as the support script directory
[11:21:04] Info: Using '/usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /bin /sbin /usr/libexec /usr/local/libexec' as the command directories
[11:21:04] Info: Using '/var/lib/rkhunter/tmp' as the temporary directory
[11:21:04] Info: No mail-on-warning address configured
[11:21:04] Info: X will be automatically detected
[11:21:04] Info: Found the 'basename' command: /usr/bin/basename
[11:21:04] Info: Found the 'diff' command: /usr/bin/diff
[11:21:04] Info: Found the 'dirname' command: /usr/bin/dirname
[11:21:04] Info: Found the 'file' command: /usr/bin/file
[11:21:04] Info: Found the 'find' command: /usr/bin/find
[11:21:04] Info: Found the 'ifconfig' command: /usr/sbin/ifconfig
[11:21:04] Info: Found the 'ip' command: /usr/sbin/ip
[11:21:04] Info: Found the 'ipcs' command: /usr/bin/ipcs
[11:21:04] Info: Found the 'ldd' command: /usr/bin/ldd
[11:21:04] Info: Found the 'lsattr' command: /usr/bin/lsattr
...
Para obtener más información y opciones, ejecute el siguiente comando.
rkhunter --help
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