Wéi Scanner fir Rootkits, Backdoors an Exploits Mat Rootkit Hunter a Linux


Kärelen, wann Dir e reegelméissege Lieser vun linux-console.net sidd, mierkt Dir datt dëst eisen drëtten Artikel iwwer Sécherheetsinstrumenter ass. An eise fréieren zwee Artikelen hu mir Iech all d'Leedung ginn wéi Dir Apache a Linux Systeme vu Malware, DOS an DDOS Attacke mat LMD (Linux Malware Detect) séchert.

Erëm si mir hei fir en neit Sécherheetsinstrument mam Numm Rkhunter (Rootkit Hunter) aféieren. Dësen Artikel féiert Iech op e Wee fir RKH (RootKit Hunter) an Linux Systemer mat Quellcode z'installéieren an ze konfiguréieren.

Wat ass Rkhunter?

Rkhunter (Rootkit Hunter) ass en Open-Source Unix/Linux-baséiert Scanner-Tool fir Linux Systemer, déi ënner GPL verëffentlecht ginn, déi Backdoors, Rootkits a lokal Ausnotzen op Äre Systemer scannt.

Et scannt verstoppte Dateien, falsch Permissiounen op Binären, verdächteg Strings am Kernel, etc. Fir méi iwwer Rkhunter a seng Features ze wëssen, besicht http://rkhunter.sourceforge.net/.

Installéiert Rootkit Hunter Scanner a Linux Systemer

Als éischt, luet déi lescht stabil Versioun vum Rkhunter Tool erof andeems Dir op http://rkhunter.sourceforge.net/ gitt oder benotzt de Wget Kommando hei ënnen fir se op Äre Systemer erofzelueden.

# cd /tmp
# wget http://downloads.sourceforge.net/project/rkhunter/rkhunter/1.4.6/rkhunter-1.4.6.tar.gz

Wann Dir déi lescht Versioun erofgelueden hutt, lafen déi folgend Kommandoen als Root Benotzer fir se z'installéieren.

# tar -xvf rkhunter-1.4.6.tar.gz 
# cd rkhunter-1.4.6
# ./installer.sh --layout default --install
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

Fëllt den RKH Updater fir d'Datebankeigenschaften auszefëllen andeems Dir de folgende Kommando ausféiert.

# /usr/local/bin/rkhunter --update
# /usr/local/bin/rkhunter --propupd
[ 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

Erstellt e Fichier mam Numm rkhunter.sh ënner /etc/cron.daily/, deen dann Äre Dateiesystem all Dag scannt an E-Mail Notifikatiounen op Är E-Mail-ID schéckt. Erstellt déi folgend Datei mat der Hëllef vun Ärem Liiblingseditor.

# vi /etc/cron.daily/rkhunter.sh

Füügt déi folgend Zeilen vum Code derbäi an ersetzt YourServerNameHere mat Ärem Servernumm an [E-Mail geschützt] mat Ärem E-Mail-ID.

#!/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 

Setzt d'Ausféierungserlaabnes op der Datei.

# chmod 755 /etc/cron.daily/rkhunter.sh

Fir de ganze Dateiesystem ze scannen, lafen de Rkhunter als Root Benotzer.

# rkhunter --check
[ 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)

Deen uewe genannte Kommando generéiert eng Logdatei ënner /var/log/rkhunter.log mat de Scheckresultater vum Rkhunter.

# cat /var/log/rkhunter.log
[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
...

Fir méi Informatioun an Optiounen lafen w.e.g. de folgende Kommando aus.

# rkhunter --help

Wann Dir dësen Artikel gär hutt, dann ass Deelen de richtege Wee fir Merci ze soen.