Packages and Binaries:

chkrootkit

The chkrootkit security scanner searches for signs that the system is infected with a ‘rootkit’. Rootkits are a form of malware that seek to exploit security flaws to grant unauthorised access to a computer or its services, generally for malicious purposes.

chkrootkit can identify signs of over 70 different rootkits (see the project’s website for a list).

Please note that an automated tool like chkrootkit can never guarantee a system is uncompromised. Nor does every report always signify a genuine problem: human judgement and further investigation will always be needed to assure the security of your system.

Installed size: 928 KB
How to install: sudo apt install chkrootkit

chklastlog

Check lastlog file for deleted entries

[email protected]:~# man chklastlog
CHKLASTLOG(8)               System Manager's Manual              CHKLASTLOG(8)

NAME
       chklastlog - check lastlog file for deleted entries

SYNOPSIS
       chklastlog looks for users whose login has been erased from the lastlog
       database.

DESCRIPTION
       chklastlog reads all entries from /var/log/wtmp (a database of informa-
       tion about logins and logouts) and checks that every user found in this
       file has an entry in /var/log/lastlog.  It lists any users with  logins
       in wtmp but no lastlogin information. This may suggest the user account
       has been compromised and the attacker has tried to cover their tracks.

       chklastlog needs to be able to read /var/log/wtmp and  /var/log/lastlo-
       gin.   Normally these files are world-readable so no special privileges
       are required.

FILES
       /var/log/wtmp
              database of logins and logouts.

       /var/log/lastlog
              database which contains info on the last login of each user.

SEE ALSO
       wtmp(5), who(1), lastlog(8), last(1)

LIMITATIONS
       wtmp may itself be incomplete because not all programmes  record  their
       activity using utmp logging. See wtmp(8).

       chklastlog  will  not  detect missing entries if the user has logged in
       after the lastlog entry was deleted.

       This program was originally designed to run on SunOS  4.x  systems.  On
       other systems the output is undefined.

                                 Oct 23, 2021                    CHKLASTLOG(8)

chkrootkit

Scan the system for signs of rootkits

[email protected]:~# chkrootkit -h
Usage: /usr/sbin/chkrootkit [options] [test ...]
Options:
        -h                show this help and exit
        -V                show version information and exit
        -l                show available tests and exit
        -d                debug
        -q                quiet mode
        -x                expert mode
        -e 'FILE1 FILE2'  exclude files/dirs from results. Must be followed by a space-separated list of files/dirs.
                          Read /usr/share/doc/chkrootkit/README.FALSE-POSITIVES first.
        -s REGEXP         filter results of sniffer test through 'grep -Ev REGEXP' to exclude expected
                          PACKET_SNIFFERs. Read /usr/share/doc/chkrootkit/README.FALSE-POSITIVES first.
        -r DIR            use DIR as the root directory
        -p DIR1:DIR2:DIRN path for the external commands used by chkrootkit
        -n                skip NFS mounted dirs

chkrootkit-daily

Run chkrootkit and report results

[email protected]:~# man chkrootkit-daily
chkrootkit-daily(8)         System Manager's Manual        chkrootkit-daily(8)

NAME
       chkrootkit-daily - Run chkrootkit and report results

SYNOPSIS
       chkrootkit-daily

DESCRIPTION
       chkrootkit-daily  runs  chkrootkit(8) and emails the results. It is in-
       tended to be run by the systemd(1) timer or as a cron(1) job every day.

CONFIGURATION
       All options are set and documented in /etc/chkrootkit/chkrootkit.conf.

AUTHOR
       chkrootkit-daily and this manual page were written by Richard Lewis for
       the Debian project. They may be used by others.

SEE ALSO
       chkrootkit(8)

                                  2023-02-19               chkrootkit-daily(8)

chkwtmp

Check wtmp file deleted entries

[email protected]:~# man chkwtmp
CHKWTMP(8)                  System Manager's Manual                 CHKWTMP(8)

NAME
       chkwtmp - check wtmp file deleted entries

SYNOPSIS
       chkwtmp looks for data deleted from wtmp

DESCRIPTION
       chkwtmp  examines  the  file  /var/log/wtmp for entries which have been
       overwritten (containing only null-bytes). If such entries are found the
       program  displays  the  timestamps  of the entries before and after the
       deleted entry, providing an idea of when the entry was deleted.

       chkwtmp needs to be able to read /var/log/wtmp.  Normally this file  is
       world-readable so no special privileges are required.

FILES
       /var/log/wtmp
              database of logins and logouts.

SEE ALSO
       wtmp(4), who(1)

LIMITATIONS
       An  entry is recognized as overwritten if the time-information has been
       overwritten with null-bytes.

       This program was originally designed to run on SunOS  4.x  systems.  On
       other systems the output is undefined.

                                 Oct 23, 2021                       CHKWTMP(8)