Chkrootkit

                        chkrootkit V. 0.49

         Nelson Murilo <nelson@pangeia.com.br> (main author)
           Klaus Steding-Jessen <jessen@cert.br> (co-author)

         This program locally checks for signs of a rootkit.
        chkrootkit is available at: http://www.chkrootkit.org/

                No illegal activities are encouraged!
        I'm not responsible for anything you may do with it.

          This tool includes software developed by the
          DFN-CERT, Univ. of Hamburg (chklastlog and chkwtmp),
          and small portions of ifconfig developed by
          Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>.

1. What's chkrootkit?
---------------------

chkrootkit is a tool to locally check for signs of a rootkit.  It
contains:

* chkrootkit: a shell script that checks system binaries for
  rootkit modification.

* ifpromisc.c: checks if the network interface is in promiscuous
  mode.

* chklastlog.c: checks for lastlog deletions.

* chkwtmp.c: checks for wtmp deletions.

* check_wtmpx.c: checks for wtmpx deletions.  (Solaris only)

* chkproc.c: checks for signs of LKM trojans.

* chkdirs.c: checks for signs of LKM trojans.

* strings.c: quick and dirty strings replacement.

* chkutmp.c: checks for utmp deletions.

chkwtmp and chklastlog *try* to check for deleted entries in the wtmp
and lastlog files, but it is *not* guaranteed that any modification
will be detected.

Aliens tries to find sniffer logs and rootkit config files.  It looks
for some default file locations -- so it is also not guaranteed it
will succeed in all cases.

chkproc checks if /proc entries are hidden from ps and the readdir
system call.  This could be the indication of a LKM trojan.  You can
also run this command with the -v option (verbose).

2. Rootkits, Worms and LKMs detected
------------------------------------

For an updated list of rootkits, worms and LKMs detected by
chkrootkit please visit: http://www.chkrootkit.org/

3. Supported Systems
--------------------

chkrootkit has been tested on: Linux 2.0.x, 2.2.x, 2.4.x and 2.6.x,
FreeBSD 2.2.x, 3.x, 4.x and 5.x, OpenBSD 2.x, 3.x and 4.x., NetBSD
1.6.x, Solaris 2.5.1, 2.6, 8.0 and 9.0, HP-UX 11, Tru64, BSDI and Mac
OS X.

4. Package Contents
-------------------

README
README.chklastlog
README.chkwtmp
COPYRIGHT
chkrootkit.lsm

Makefile
chklastlog.c
chkproc.c
chkdirs.c
chkwtmp.c
check_wtmpx.c
ifpromisc.c
strings.c
chkutmp.c

chkrootkit

5. Installation
---------------

To compile the C programs type:

# make sense

After that it is ready to use and you can simply type:

# ./chkrootkit

6. Usage
--------

chkrootkit must run as root.  The simplest way is:

# ./chkrootkit

This will perform all tests.  You can also specify only the tests you
want, as shown below:

Usage: ./chkrootkit [options] [testname ...]
Options:
        -h                show this help and exit
        -V                show version information and exit
        -l                show available tests
        -d                debug
        -q                quiet mode
        -x                expert mode
        -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

Where testname stands for one or more from the following list:

aliens asp bindshell lkm rexedcs sniffer w55808 wted scalper slapper
z2 chkutmp amd basename biff chfn chsh cron crontab date du dirname
echo egrep env find fingerd gpm grep hdparm su ifconfig inetd
inetdconf identd init killall ldsopreload login ls lsof mail mingetty
netstat named passwd pidof pop2 pop3 ps pstree rpcinfo rlogind rshd
slogin sendmail sshd syslogd tar tcpd tcpdump top telnetd timed
traceroute vdir w write

For example, the following command checks for trojaned ps and ls
binaries and also checks if the network interface is in promiscuous
mode.

  # ./chkrootkit ps ls sniffer

The `-q' option can be used to put chkrootkit in quiet mode -- in
this mode only output messages with `infected' status are shown.

With the `-x' option the user can examine suspicious strings in the
binary programs that may indicate a trojan -- all the analysis is
left to the user.

Lots of data can be seen with:

  # ./chkrootkit -x | more

Pathnames inside system commands:

  # ./chkrootkit -x | egrep '^/'

chkrootkit uses the following commands to make its tests: awk, cut,
egrep, find, head, id, ls, netstat, ps, strings, sed, uname.  It is
possible, with the `-p' option, to supply an alternate path to
chkrootkit so it won't use the system's (possibly) compromised
binaries to make its tests.

To use, for example, binaries in /cdrom/bin:

  # ./chkrootkit -p /cdrom/bin

It is possible to add more paths with a `:'

  # ./chkrootkit -p /cdrom/bin:/floppy/mybin

Sometimes is a good idea to mount the disk from a compromised machine
on a machine you trust.  Just mount the disk and specify a new
rootdir with the `-r' option.

For example, suppose the disk you want to check is mounted under
/mnt, then:

  # ./chkrootkit -r /mnt

7. Output Messages
------------------

The following messages are printed by chkrootkit (except with the -x
and -q command options) during its tests:

  "INFECTED": the test has identified a command probably modified by
  a known rootkit;

  "not infected": the test didn't find any known rootkit signature.

  "not tested": the test was not performed -- this could happen in
  the following situations:
    a) the test is OS specific;
    b) the test depends on an external program that is not available;
    c) some specific command line options are given. (e.g. -r ).

  "not found": the command to be tested is not available;

  "Vulnerable but disabled": the command is infected but not in use.
  (not running or commented in inetd.conf)

8. A trojaned command has been found.  What should I do now?
------------------------------------------------------------

Your biggest problem is that your machine has been compromised and
this bad guy has root privileges.

Maybe you can solve the problem by just replacing the trojaned
command -- the best way is to reinstall the machine from a safe media
and to follow your vendor's security recommendations.

9. Reports and questions
------------------------

Please send comments, questions and bug reports to
nelson@pangeia.com.br and jessen@cert.br.

A simple FAQ and Related information about rootkits and security can
be found at chkrootkit's homepage, http://www.chkrootkit.org.

Referensi

• http://www.chkrootkit.org
• http://www.chkrootkit.org/download/

Pranala Menarik

• chkrootkit: di ubuntu
• Keamanan Jaringan