rkhunter – cacciatore di rootkits e software malevole – debian 9.xx ( stretch )

rkhunter è uno script che analizza il filesytem alla ricerca di applicazioni malevole: rootkits, backdoors (cavalli di troia)  e altri rischi per la sicurezza. Un rootkits consente all’attaccante di avere  un accesso di tipo privilegiato al computer/server. rkhunter permette di capire se il computer/server è stato compromesso.  E’ buona norma ultilizzare anche  altri software di controllo ad esempio: chkrootkit .

Tra i controlli effettuati :

  • compazione delle impronte dei files importanti con quelle contenute in database online,
  • ricerca di directory e files dei rootkits conosciuti,
  • ricerca di  errori nei permessi nei file binari,
  • ricerca di  file e cartelle nascoste,
  • ricerca di stringhe sospette nei moduli kernel,
  • controllo dei file di configurazione di SSHD

rkhunter si installa al solito con

sudo apt install rkhunter

Per evitare warning inutili è opportuno modificare il file di configurazione /etc/rkhunter.conf.local  indicando il package manager

In debian 9.xx cambiare il valore di default NONE in DPKG

...
#PKGMGR=NONE
...

in

PKGMGR=DPKG

aggiornare anche il file database delle proprietà con i comandi

sudo rkhunter --propupd

e

sudo rkhunter --update

Lo scanner si avvia manualmente con

sudo rkhunter -c

Per informazioni più dettagliate sul controllo effettuato è possible consultare  il file .log in /var/log/rkhunter.log

Per quanto attiene ai warning va considerato che rkhunter

 

esempio di listato generato da rkhunter

maurizio# rkhunter -c
[ Rootkit Hunter version 1.4.2 ]

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/sbin/adduser                                        [ OK ]
    /usr/sbin/chroot                                         [ OK ]
    /usr/sbin/cron                                           [ OK ]
    /usr/sbin/groupadd                                       [ OK ]
    /usr/sbin/groupdel                                       [ OK ]
    /usr/sbin/groupmod                                       [ OK ]
    /usr/sbin/grpck                                          [ OK ]
    /usr/sbin/nologin                                        [ OK ]
    /usr/sbin/pwck                                           [ OK ]
    /usr/sbin/rsyslogd                                       [ OK ]
    /usr/sbin/sshd                                           [ OK ]
    /usr/sbin/tcpd                                           [ OK ]
    /usr/sbin/useradd                                        [ OK ]
    /usr/sbin/userdel                                        [ OK ]
    /usr/sbin/usermod                                        [ OK ]
    /usr/sbin/vipw                                           [ OK ]
    /usr/sbin/unhide                                         [ OK ]
    /usr/sbin/unhide-linux                                   [ OK ]
    /usr/sbin/unhide-posix                                   [ OK ]
    /usr/sbin/unhide-tcp                                     [ OK ]
    /usr/bin/awk                                             [ OK ]
    /usr/bin/basename                                        [ OK ]
    /usr/bin/chattr                                          [ OK ]
    /usr/bin/curl                                            [ OK ]
    /usr/bin/cut                                             [ OK ]
    /usr/bin/diff                                            [ OK ]
    /usr/bin/dirname                                         [ OK ]
    /usr/bin/dpkg                                            [ OK ]
    /usr/bin/dpkg-query                                      [ OK ]
    /usr/bin/du                                              [ OK ]
    /usr/bin/env                                             [ OK ]
    /usr/bin/file                                            [ OK ]
    /usr/bin/find                                            [ OK ]
    /usr/bin/GET                                             [ OK ]
    /usr/bin/groups                                          [ OK ]
    /usr/bin/head                                            [ OK ]
    /usr/bin/id                                              [ OK ]
    /usr/bin/killall                                         [ OK ]
    /usr/bin/last                                            [ OK ]
    /usr/bin/lastlog                                         [ OK ]
    /usr/bin/ldd                                             [ OK ]
    /usr/bin/less                                            [ OK ]
    /usr/bin/logger                                          [ OK ]
    /usr/bin/lsattr                                          [ OK ]
    /usr/bin/lsof                                            [ OK ]
    /usr/bin/mail                                            [ OK ]
    /usr/bin/md5sum                                          [ OK ]
    /usr/bin/newgrp                                          [ OK ]
    /usr/bin/passwd                                          [ OK ]
    /usr/bin/perl                                            [ OK ]
    /usr/bin/pgrep                                           [ OK ]
    /usr/bin/pkill                                           [ OK ]
    /usr/bin/pstree                                          [ OK ]
    /usr/bin/rkhunter                                        [ OK ]
    /usr/bin/runcon                                          [ OK ]
    /usr/bin/sha1sum                                         [ OK ]
    /usr/bin/sha224sum                                       [ OK ]
    /usr/bin/sha256sum                                       [ OK ]
    /usr/bin/sha384sum                                       [ OK ]
    /usr/bin/sha512sum                                       [ OK ]
    /usr/bin/size                                            [ OK ]
    /usr/bin/sort                                            [ OK ]
    /usr/bin/ssh                                             [ OK ]
    /usr/bin/stat                                            [ OK ]
    /usr/bin/strings                                         [ OK ]
    /usr/bin/sudo                                            [ OK ]
    /usr/bin/tail                                            [ OK ]
    /usr/bin/test                                            [ OK ]
    /usr/bin/top                                             [ OK ]
    /usr/bin/touch                                           [ OK ]
    /usr/bin/tr                                              [ OK ]
    /usr/bin/uniq                                            [ OK ]
    /usr/bin/users                                           [ OK ]
    /usr/bin/vmstat                                          [ OK ]
    /usr/bin/w                                               [ OK ]
    /usr/bin/watch                                           [ OK ]
    /usr/bin/wc                                              [ OK ]
    /usr/bin/wget                                            [ OK ]
    /usr/bin/whatis                                          [ OK ]
    /usr/bin/whereis                                         [ OK ]
    /usr/bin/which                                           [ OK ]
    /usr/bin/who                                             [ OK ]
    /usr/bin/whoami                                          [ OK ]
    /usr/bin/mawk                                            [ OK ]
    /usr/bin/lwp-request                                     [ OK ]
    /usr/bin/mail.mailutils                                  [ OK ]
    /usr/bin/x86_64-linux-gnu-size                           [ OK ]
    /usr/bin/x86_64-linux-gnu-strings                        [ OK ]
    /usr/bin/w.procps                                        [ OK ]
    /sbin/depmod                                             [ OK ]
    /sbin/fsck                                               [ OK ]
    /sbin/ifconfig                                           [ OK ]
    /sbin/ifdown                                             [ OK ]
    /sbin/ifup                                               [ OK ]
    /sbin/init                                               [ OK ]
    /sbin/insmod                                             [ OK ]
    /sbin/ip                                                 [ OK ]
    /sbin/lsmod                                              [ OK ]
    /sbin/modinfo                                            [ OK ]
    /sbin/modprobe                                           [ OK ]
    /sbin/rmmod                                              [ OK ]
    /sbin/route                                              [ OK ]
    /sbin/runlevel                                           [ OK ]
    /sbin/sulogin                                            [ OK ]
    /sbin/sysctl                                             [ OK ]
    /bin/bash                                                [ OK ]
    /bin/cat                                                 [ OK ]
    /bin/chmod                                               [ OK ]
    /bin/chown                                               [ OK ]
    /bin/cp                                                  [ OK ]
    /bin/date                                                [ OK ]
    /bin/df                                                  [ OK ]
    /bin/dmesg                                               [ OK ]
    /bin/echo                                                [ OK ]
    /bin/egrep                                               [ OK ]
    /bin/fgrep                                               [ OK ]
    /bin/fuser                                               [ OK ]
    /bin/grep                                                [ OK ]
    /bin/ip                                                  [ OK ]
    /bin/kill                                                [ OK ]
    /bin/less                                                [ OK ]
    /bin/login                                               [ OK ]
    /bin/ls                                                  [ OK ]
    /bin/lsmod                                               [ OK ]
    /bin/mktemp                                              [ OK ]
    /bin/more                                                [ OK ]
    /bin/mount                                               [ OK ]
    /bin/mv                                                  [ OK ]
    /bin/netstat                                             [ OK ]
    /bin/ping                                                [ OK ]
    /bin/ps                                                  [ OK ]
    /bin/pwd                                                 [ OK ]
    /bin/readlink                                            [ OK ]
    /bin/sed                                                 [ OK ]
    /bin/sh                                                  [ OK ]
    /bin/su                                                  [ OK ]
    /bin/touch                                               [ OK ]
    /bin/uname                                               [ OK ]
    /bin/which                                               [ OK ]
    /bin/kmod                                                [ OK ]
    /bin/systemd                                             [ OK ]
    /bin/systemctl                                           [ OK ]
    /bin/dash                                                [ OK ]
    /lib/systemd/systemd                                     [ 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 ]
    Apache Worm                                              [ Not found ]
    Ambient (ark) Rootkit                                    [ Not found ]
    Balaur Rootkit                                           [ Not found ]
    BeastKit Rootkit                                         [ Not found ]
    beX2 Rootkit                                             [ Not found ]
    BOBKit Rootkit                                           [ Not found ]
    cb Rootkit                                               [ Not found ]
    CiNIK Worm (Slapper.B variant)                           [ Not found ]
    Danny-Boy's Abuse Kit                                    [ Not found ]
    Devil RootKit                                            [ Not found ]
    Dica-Kit Rootkit                                         [ Not found ]
    Dreams Rootkit                                           [ Not found ]
    Duarawkz Rootkit                                         [ Not found ]
    Enye LKM                                                 [ Not found ]
    Flea Linux Rootkit                                       [ Not found ]
    Fu Rootkit                                               [ Not found ]
    Fuck`it Rootkit                                          [ Not found ]
    GasKit Rootkit                                           [ Not found ]
    Heroin LKM                                               [ Not found ]
    HjC Kit                                                  [ Not found ]
    ignoKit Rootkit                                          [ Not found ]
    IntoXonia-NG Rootkit                                     [ Not found ]
    Irix Rootkit                                             [ Not found ]
    Jynx Rootkit                                             [ Not found ]
    KBeast Rootkit                                           [ Not found ]
    Kitko Rootkit                                            [ Not found ]
    Knark Rootkit                                            [ Not found ]
    ld-linuxv.so Rootkit                                     [ Not found ]
    Li0n Worm                                                [ Not found ]
    Lockit / LJK2 Rootkit                                    [ Not found ]
    Mood-NT Rootkit                                          [ Not found ]
    MRK Rootkit                                              [ Not found ]
    Ni0 Rootkit                                              [ Not found ]
    Ohhara Rootkit                                           [ Not found ]
    Optic Kit (Tux) Worm                                     [ Not found ]
    Oz Rootkit                                               [ Not found ]
    Phalanx Rootkit                                          [ Not found ]
    Phalanx2 Rootkit                                         [ Not found ]
    Phalanx2 Rootkit (extended tests)                        [ Not found ]
    Portacelo Rootkit                                        [ Not found ]
    R3dstorm Toolkit                                         [ Not found ]
    RH-Sharpe's Rootkit                                      [ Not found ]
    RSHA's Rootkit                                           [ Not found ]
    Scalper Worm                                             [ Not found ]
    Sebek LKM                                                [ Not found ]
    Shutdown Rootkit                                         [ Not found ]
    SHV4 Rootkit                                             [ Not found ]
    SHV5 Rootkit                                             [ Not found ]
    Sin Rootkit                                              [ Not found ]
    Slapper Worm                                             [ Not found ]
    Sneakin Rootkit                                          [ Not found ]
    'Spanish' Rootkit                                        [ Not found ]
    Suckit Rootkit                                           [ Not found ]
    Superkit Rootkit                                         [ Not found ]
    TBD (Telnet BackDoor)                                    [ Not found ]
    TeLeKiT Rootkit                                          [ Not found ]
    T0rn Rootkit                                             [ Not found ]
    trNkit Rootkit                                           [ Not found ]
    Trojanit Kit                                             [ Not found ]
    Tuxtendo Rootkit                                         [ Not found ]
    URK Rootkit                                              [ Not found ]
    Vampire Rootkit                                          [ Not found ]
    VcKit Rootkit                                            [ Not found ]
    Volc Rootkit                                             [ Not found ]
    Xzibit Rootkit                                           [ Not found ]
    zaRwT.KiT Rootkit                                        [ Not found ]
    ZK Rootkit                                               [ 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 ]

  Performing malware checks
    Checking running processes for suspicious files          [ None found ]
    Checking for login backdoors                             [ None found ]
    Checking for suspicious directories                      [ None found ]
    Checking for sniffer log files                           [ None found ]
    Suspicious Shared Memory segments                        [ None found ]

  Performing Linux specific checks
    Checking loaded kernel modules                           [ OK ]
    Checking kernel module names                             [ OK ]

[Press  to continue]


Checking the network...

  Performing checks on the network ports
    Checking for backdoor ports                              [ None found ]
    Checking for hidden ports                                [ None found ]

  Performing checks on the network interfaces
    Checking for promiscuous interfaces                      [ None found ]

Checking the local host...

  Performing system boot checks
    Checking for local host name                             [ Found ]
    Checking for system startup files                        [ Found ]
    Checking system startup files for malware                [ None found ]

  Performing group and account checks
    Checking for passwd file                                 [ Found ]
    Checking for root equivalent (UID 0) accounts            [ None found ]
    Checking for passwordless accounts                       [ None found ]
    Checking for passwd file changes                         [ None found ]
    Checking for group file changes                          [ None found ]
    Checking root account shell history files                [ OK ]

  Performing system configuration file checks
    Checking for an SSH configuration file                   [ Found ]
    Checking if SSH root access is allowed                   [ Not allowed ]
    Checking if SSH protocol v1 is allowed                   [ Not allowed ]
    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 ]

  Performing filesystem checks
    Checking /dev for suspicious file types                  [ None found ]
    Checking for hidden files and directories                [ Warning ]

[Press  to continue]

System checks summary
=====================

File properties checks...
    Files checked: 144
    Suspect files: 0

Rootkit checks...
    Rootkits checked : 378
    Possible rootkits: 0

Applications checks...
    All checks skipped

The system checks took: 6 minutes and 46 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)

Checking for hidden files and directories [ Warning ]

dettagli relativi al warning file /var/log/rkhunter.log

Viene evidenziata la presenza della cartella nascosta  .java che non rappresenta in questo caso non rappresenta un fattore critico.

 

rkhunter lista dei tests

 rkhunter --list tests

Current test names:
    additional_rkts all apps attributes avail_modules deleted_files
    filesystem group_accounts group_changes hashes hidden_ports hidden_procs
    immutable known_rkts loaded_modules local_host malware network
    none os_specific other_malware packet_cap_apps passwd_changes ports
    possible_rkt_files possible_rkt_strings promisc properties rootkits running_procs
    scripts shared_libs shared_libs_path startup_files startup_malware strings
    suspscan system_commands system_configs trojans

Grouped test names:
    additional_rkts => possible_rkt_files possible_rkt_strings 
    group_accounts  => group_changes passwd_changes 
    local_host      => filesystem group_changes passwd_changes startup_malware system_configs 
    malware         => deleted_files hidden_procs other_malware running_procs suspscan 
    network         => hidden_ports packet_cap_apps ports promisc 
    os_specific     => avail_modules loaded_modules 
    properties      => attributes hashes immutable scripts 
    rootkits        => avail_modules deleted_files hidden_procs known_rkts loaded_modules other_malware possible_rkt_files possible_rkt_strings running_procs suspscan trojans 
    shared_libs     => shared_libs_path 
    startup_files   => startup_malware 
    system_commands => attributes hashes immutable scripts shared_libs_path strings 

 

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