Network Security Hacks [Electronic resources] نسخه متنی

Hack 60 Log User Activity with Process Accounting

Keep a detailed audit trail of
what's being done on your systems.

Process accounting allows you to
keep detailed logs of every command a user runs, including CPU time
and memory used. From a security
standpoint, this means the system administrator can gather
information about what user ran which command and at what
time. This is not only very useful
in assessing a break-in or local root compromise, but can also be
used to spot attempted malicious behavior by normal users of the
system. (Remember that intrusions don't always come
from the outside.)

To enable process accounting, run these commands:

# mkdir /var/account
# touch /var/account/pacct && chmod 660 /var/account/pacct
# /sbin/accton /var/account/pacct

Alternatively, if you are running Red Hat or SuSE Linux and have the
process accounting package installed, you can run a startup script to
enable process accounting. On Red
Hat, try this:

# chkconfig psacct on
# /sbin/service psacct start

On SuSE, use these commands:

# chkconfig acct on
# /sbin/service acct start

The process accounting package provides several programs to make use
of the data that is being logged.
The ac

program analyzes total connect time
for users on the system.

Running it without any arguments prints out the number of hours
logged by the current user:

[andrew@colossus andrew]$ ac
total      106.23

If you want to display connect time for all users who have logged
onto the system, use the -p switch:

# ac -p
root                                 0.07
andrew                             106.05
total      106.12

The lastcomm
command lets you
search the accounting logs by username, command name, or terminal:

# lastcomm andrew
ls                      andrew   ??         0.01 secs Mon Dec 15 05:58
rpmq                    andrew   ??         0.08 secs Mon Dec 15 05:58
sh                      andrew   ??         0.03 secs Mon Dec 15 05:44
gunzip                  andrew   ??         0.00 secs Mon Dec 15 05:44
# lastcomm bash 
bash               F    andrew   ??         0.00 secs Mon Dec 15 06:44
bash               F    root     stdout     0.01 secs Mon Dec 15 05:20
bash               F    root     stdout     0.00 secs Mon Dec 15 05:20
bash               F    andrew   ??         0.00 secs Mon Dec 15 05:19

To summarize the accounting information, you can use the
sa
command. By default it
will list all the commands found in the accounting logs and print the
number of times that each one has been executed:

# sa
14       0.04re       0.03cp         0avio      1297k   troff
7       0.03re       0.03cp         0avio       422k   lastcomm
2      63.90re       0.01cp         0avio       983k   info
14      34.02re       0.01cp         0avio       959k   less
14       0.03re       0.01cp         0avio      1132k   grotty
44       0.02re       0.01cp         0avio       432k   gunzip

You can also use the -u flag to output per-user
statistics:

# sa -u
root       0.01 cpu      344k mem      0 io which            
root       0.00 cpu     1094k mem      0 io bash
root       0.07 cpu     1434k mem      0 io rpmq
andrew     0.02 cpu      342k mem      0 io id               
andrew     0.00 cpu      526k mem      0 io bash
andrew     0.01 cpu      526k mem      0 io bash
andrew     0.03 cpu      378k mem      0 io grep             
andrew     0.01 cpu      354k mem      0 io id               
andrew     0.01 cpu      526k mem      0 io bash
andrew     0.00 cpu      340k mem      0 io hostname

You can peruse the output of these commands every so often to look
for suspicious activity, such as increases in CPU usage or commands
that are known to be used for mischief.