NAME
checksecurity - check for changes to setuid programs
SYNOPSIS
checksecurity
DESCRIPTION
The
checksecurity
command scans the mounted files systems (subject to the filter defined
in /etc/checksecurity.conf) and compares the list of setuid programs to the
list created on the previous run. Any changes are printed to standard
output. Also, it generates a list of
nfs
and
afs
filesystems that are mounted insecurely (i.e. they are missing the
nodev
and either the
noexec
or
nosuid
flags).
checksecurity
is run by
cron
on a daily basis, and the output stored in /var/log/setuid/setuid.changes.
CONFIGURATION
The
checksecurity.conf
file defines several configuration variables:
R CHECKSECURITY_FILTER ,
R CHECKSECURITY_NOFINDERRORS ,
R CHECKSECURITY_NONFSAFS ,
R CHECKSECURITY_EMAIL ,
R CHECKSECURITY_DEVICEFILTER ,
R CHECKSECURITY_PATHFILTER ,
and
R LOGDIR .
Each is described below.
The
CHECKSECURITY_FILTER
environment variable which is the argument of 'grep -vE' applied to
the output of the
mount
command. In other words, the value of
CHECKSECURITY_FILTER
is a regular expression that removes matching lines from those
file systems that will be scanned. The default value removes
all file systems of type
proc, bind, msdos, iso9660, ncpfs, nfs, afs,
smbfs, auto, ntfs, coda
file systems,
anything mounted on /dev/fd*, anything mounted
on /mnt or /amd, and anything mounted with option nosuid or noexec.
The
checksecurity.conf
file is sourced from
checksecurity,
so you could do some fairly tricky things to define
R CHECKSECURITY_FILTER .
The
CHECKSECURITY_NOFINDERRORS
environment variable, if set to the literal "TRUE", disables
find errors from checksecurity (actually, it re-routes them to
/dev/null
).
The
CHECKSECURITY_NONFSAFS
environment variable, if set to the literal "TRUE", disables the message about
nfs
and
afs
file systems that are mounted without the
nodev
and either the
noexec
or
nosuid
options.
If set, the
CHECKSECURITY_EMAIL
variable defines who is sent a copy of the setuid.changes file.
The
CHECKSECURITY_DEVICEFILTER
variable specifies a
find
clause for which matching block and character device files will not be
monitored for changing owners and permissions. For example, if you
didn't want to check for permission changes on tty device files
beneath /dev, you could set the following:
CHECKSECURITY_DEVICEFILTER='-path /dev/tty*'
Note that any added or modified suid programs under that path would
still be detected. If you want to specify multiple expressions,
separate them with '-o', but there is no need to surround the whole
clause with parentheses. To disable this filter, specify it as
'-false' (which is the default).
The
CHECKSECURITY_PATHFILTER
variable specifies a
find
clause which will be pruned from the search path.
This means that the entire subtree will be completely skipped.
Thus, specifying
CHECKSECURITY_PATHFILTER='-path /var/ftp'
then the entire /var/ftp tree will be skipped. To disable this filter,
specify it as '-false' (which is the default).
LOGDIR
sets the name of the directory which stores the files which track
the permission and ownership changes. By default, they are in
R /var/log/setuid .
FILES
/etc/checksecurity.conf
checksecurity configuration file
/var/log/setuid/setuid.today
setuid files from the most recent run
/var/log/setuid/setuid.yesterday
setuid files from the previous run
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