Ubuntu Manpage: tiger - UNIX Security Checker

NAME

       tiger - UNIX Security Checker

SYNOPSIS

       tiger  [-vthqGSH]  [-B  dir]  [-l  dir|@host] [-w dir] [-b dir] [-e|-E] [-c config] [-A arch] [-O os] [-R
       release]

DESCRIPTION

       Tiger is a package consisting of Bourne Shell scripts, C code and data files which is used  for  checking
       for  security  problems  on  a  UNIX system.  It scans system configuration files, file systems, and user
       configuration files for possible security problems and reports them.  The command tigexp(8) can  be  used
       to obtain explanations of the problems reported by tiger.

       You  can  configure tiger by adjusting the Tiger_ variables in the /etc/tiger/tigerrc configuration file.
       For each available module (see MODULES below) there is a corresponding variable in the configuration file
       that determines whether the module is run. All of the variables names start with Tiger_check_ and  should
       be  set  equal to Y to run, or N to skip. Other configuration variables will modify the behaviour of some
       modules, and should be adjusted based on the operating system.

       The /etc/tiger/tiger.ignore configuration file defines a set of messages that will not  be  presented  in
       the  report even if any of the modules generate them.  If the file exists, all the entries (line by line)
       are used as extended regular expressions that are compared against each  message  (notice  that  it  will
       introduce  some  overhead which grows with the size of the file).  For more information on this mechanism
       read the README.ignore document.

OPTIONS

The following arguments can be used when calling the program:

-B tigerdir
Specify the directory where tiger is installed. If not specified, /usr/lib/tiger is used.

-l logdir|@logserver
Specify the name of the directory where tiger will write the security report. This defaults to
/var/log/tiger. The filename of the report will be of the form
'security.report.hostname.date.time'. If the directory begins with a @, the name will be
interpreted as a tiger logging server. Tiger logging's server is currently a server that listens
in port (tcp) 5353 on a remote host. The tiger process will just send the results to that server
using a telnet connection.

-w workdir
Specify a directory to use for creating scratch files. This defaults to /var/lib/tiger/work.

-b bindir
Specify the directory which contains (or will contain) the binaries generated from the C modules.
If the systems directories contain all the binaries, they will be used directly from there. If
not, then if bindir contains the binaries, these will be used. If none are found in either place,
then an attempt will be made to compile the C code and install the executables into bindir.

-c tigerrc
Specify an alternate name for the tigerrc control file. The default is '/etc/tiger/tigerrc'.

-e This option will cause explanations to be inserted into the security report following each
message. This can greatly increase the size of the report, as explanations may appear repeatedly.

-E This option indicates that a separate explanation report should be created, with explanations for
each type of message only appearing once. The filename of the explanation report will be of the
form 'explain.report.hostname.date.time'.

-G Generate the signatures (MD5 hashes and file permissions) for system binary files.

-H This option will format the report into HTML creating local links to the problem descriptions.

-S This option indicates that a surface level check of the configuration files of any diskless
clients served by this machine should be checked at the same time. The checks will not be as in
depth as they would be if run on the client itself.

-q Suppress messages to be as quiet as possible, only security messages will be shown.

-A arch
This option overrides the default value obtained for the current architecture detected by the
internal configuration engine to a value defined by the user.

-O os This option overrides the default value obtained for the current operating system detected by the
internal configuration engine to a value defined by the user.

-R release
This option overrides the default value obtained for the current operating system release detected
by the internal configuration engine to a value defined by the user.

Notice that changing the real values for the operating system and architecture Tiger is running in might
result in scripts being run which are not appropriate to it, and, as a consequence, unexpected (and
potentially dangerous) errors might be generated. When executed Tiger will show which operating system,
release and architecture thinks it is running in.

MODULES

Tiger is composed of a series of modules. Each of these modules check specific security issues related to
UNIX systems. The framework provided by Tiger allows the provision of both generic modules and those
specific for the operating system the software runs in. Modules can be executed stand alone, from cron or
through the tiger program (which will execute all those available).

If you want to write additional modules for your system read the README.writemodules document.

Tiger currently provides the following modules:

check_accounts
Checks the accounts provided in the system, looking for disabled accounts with cron, rhosts,
.forward, and valid shells.

check_aliases
Performs a check for mail aliases and improper configuration.

check_anonftp
Determines if the anonymous FTP service is properly configured.

check_cron
Validates the cron entries in the system.

check_embedded
Determines if embedded pathnames are configured properly.

check_exports
Analyses configuration files for NFS exported filesystems to see if access is properly restricted.

check_group
Checks the UNIX groups available in the system, looking for conflicts and improper entries.

check_inetd
Checks the inetd configuration file: compares against services definition, valid directory paths,
non-existent binaries and active services.

check_known
Looks for known intrusion signs including backdoors and mail spools.

check_netrc
Checks if users's netrc files are insecurely configured.

check_nisplus
Looks for wrong configuration in the NIS+ entries.

check_passwd
Checks the UNIX users available in the system, looking for conflicts and improper entries.

check_path
Validates the binaries in user's PATHs as well as PATH definitions used by scripts in order to
determine insecure definitions.

check_perms
Check filepermissions and inconsistencies.

check_printcap
Analyses the configuration for the printer control file.

check_rhosts
Checks rhosts files in order to see if user's configuration leaves the system open to attack.

check_sendmail
Checks sendmail configuration files. check_signatures Compares binary files signatures against
those stored in the local database (provided with the program).

check_system
This module calls the operating system's specific modules available at /usr/lib/tiger/systems/.

check_apache
Checks the Apache configuration file and reports on generic issues which might introduce exposures
or vulnerabilities in the system.

check_devices
Checks for devices's permissions, warning about devices that have world permissions.

check_exrc
Analyses .exrc files that are not in user's home directories. The vi command will look for the
existence of such a file in the current directory, and so may inadvertently perform commands that
can compromise your system's security when starting vi or ex.

check_finddeleted
Checks if deleted files are being used by any process in the current system. This might be an
indication of intrusion (a user executing processes and then deleting its files) or of unpatched
servers (which, if not restarted use old library files and are still vulnerable).

check_ftpusers
Analyses the system's /etc/ftpusers and determines if the administrative users are in that file.

check_issue
Checks the /etc/issue and /etc/issue.net file to determine if they contain the appropriate content
(this is defined in the ISSUEFILE and ISSUENETFILE).

check_logfiles
Checks for the existence of log files (wtmp, btmp, lastlog and utmp). It will also check for
proper umask settings.

check_bootloader
Analyses configuration files for different bootloaders including lilo and grub (Linux-specific).

check_listeningprocs
Checks for processes listening on TCP/IP sockets (servers) in the system as well as users running
them. Will warn if the user running a server is not an authorised one or if the server is
listening on all available interfaces.

check_passwdformat
Checks the format of the /etc/passwd file in order to determine inconsistencies which indicate an
intrusion or misconfiguration.

check_patches
Checks if patches are available for the system (i.e. new packages). It will use autorpm or
apt-get to check this (so this tools need to be properly configured). This check is specific to
Linux (RedHat or Debian).

check_root
Checks if remote root login is allowed to the local system.

check_rootdir
Checks the permissions for the root directory.

check_rootkit
Tries to find systems which have been rootkited, it does so by looking for trojaned ls and find
commands. It also includes a wrapper to run the chkrootkit program and format the results in
Tiger's message format.

check_single
Checks if the system is properly configured to disallow single-user access. This check is specific
to Linux.

check_release
Analyses the version of the operating system and determines if it is too out of date. This check
is specific to Linux (RedHat or Debian).

check_runprocs
This module will check if the processes configured in tigerrc are running currently in the system.
If any of the processes is not running, Tiger will warn the administrator (this acts as a
lightweight software watchdog)

check_services
Check which services are configured in the system (usually in /etc/services) versus the ones that
should be configured (in the provided services file)

check_tcpd
Tests for the existence of tcp-wrappers and changes in their configuration it also determines
which services are running wrapped in tcp-wrappers.

check_umask
Check for umask setting in configuration files.

check_xinetd
Checks which xinetd services are enabled or disabled.

crack_run
Runs a local installation of the Crack program which can be used to determine if local user
passwords are easy (or not) to guess.

tripwire_run aide_run integrit_run
Wrappers for a number of integrity checkers, these programs enhance the support of Tiger for MD5
and SHA-1 binary signatures and file system permission checks (implemented with the the
check_perms and check_signatures scripts). You should consider installing any of these three
programs (Tripwire, Aide or Integrit) and use read-only locations (such as CD-ROM) to store the
hashes of the system.

deb_checkmd5sums
Compares the MD5 sums of binary files against those provided after installation. Changes in these
files might be an indication of a compromised system (Debian-specific).

deb_nopackfiles
Looks for files installed in the system's directories that are not provided by any installed
Debian packages (Debian-specific).

FILES

       /etc/tiger/tigerrc
              Configuration file for the Tiger tool.

       /etc/tiger/cronrc
              Configuration file for the Tigercron tool.

       /var/log/tiger
              Location of the log messages generated by Tiger when run through cron.

       /var/lib/tiger/work
              Working directory used by Tiger scripts to create temporary files.

       /etc/tiger/tiger.ignore
              Configuration file that defines which messages generated by modules will be ignored by  Tiger  and
              will not be presented in the final report.

BUGS

       There are a lot more things to check.

       Some places in the package are not shell meta-character or white-space safe.

       You can report or read known bugs at the http://savannah.nongnu.org/projects/tiger webpage.

       For  Debian-specific  (known)  bugs  read  the   /usr/share/doc/tiger/README.Debian   document   or   the
       http://bugs.debian.org/tiger webpage.

AUTHOR

       Tiger  was  originally  developed  by  a  team  of  the  Texas A&M University Supercomputer Center, as of
       September 1993, the development done via the Network Group, Computing & Information Services.

       This software was written originally by Douglas Lee Schales, Dave K. Hess, Khalid Warraich, and  Dave  R.
       Safford (circa 1993).

       A  lot  of  changes  were  introduced  by  the  ARSC  team (a.k.a. the TARA team) Liam Forbes <lforbes at
       arsc.edu>, Nathan Bills <bills AT arsc.edu> and  Mike  Kienenberger  <mkienenb  at  arsc.edu>,  including
       support for quite a number of operating systems.

       Current  upstream maintenance of Tiger is being done by Javier Fernandez-Sanguino Peña and coordinated at
       http://savannah.nongnu.org/projects/tiger.

       The adaptation for the GNU/Linux operating system was made by Robert L. Ziegler <rlz at mediaone.net>

       The modifications for the Debian GNU/Linux operating system have been made by  Javier  Fernandez-Sanguino
       Peña  <jfs  at  computer.org>,  including  a  number  of  checks  for  the  GNU/Linux  operating  systems
       (check_listeningprocs)  and  some  specific  for  Debian   (deb_checkadvisories,   deb_checkmd5sums   and
       deb_nopackfiles).

Security                                         12 August 2003                                         TIGER(8)