Security Breach?

Martyn martyn at chetnet.co.uk
Tue Apr 6 22:24:10 CEST 2010


Hi all, hope you can help me out with this question I have just been sent
which is as follows: -

"We have had a security warning from the hosting company, one of the Nagios
User processes was using up 90% of the CPU:

8521 nagios 25 0 6144 2168 1524 R 90.4 0.0 566:17.51 x

A review of the users access logs show this appeared to start last night,
and the account has been remotely logged in to, suggesting its fully
compromised:

nagios pts/3 :pts/1:S.0 Sat Apr 3 11:35 - 11:36 (00:00)
nagios pts/3 :pts/1:S.0 Sat Apr 3 11:32 - 11:35 (00:03)
nagios pts/3 :pts/1:S.0 Sat Apr 3 01:41 - 11:30 (09:49)
nagios pts/1 79.119.233.48 Sat Apr 3 01:36 - 15:36 (13:59)
nagios pts/3 :pts/1:S.0 Fri Apr 2 23:50 - 01:36 (01:45)
nagios pts/3 :pts/1:S.0 Fri Apr 2 22:25 - 23:37 (01:12)
nagios pts/1 79.119.233.48 Fri Apr 2 20:55 - 01:36 (04:41)
nagios pts/3 :pts/1:S.0 Fri Apr 2 12:47 - 13:18 (00:31)
nagios pts/3 :pts/1:S.0 Fri Apr 2 10:50 - 12:47 (01:56)
nagios pts/3 :pts/1:S.0 Fri Apr 2 10:49 - 10:49 (00:00)
nagios pts/2 :pts/1:S.0 Fri Apr 2 10:36 - 10:49 (00:12)
nagios pts/2 :pts/1:S.0 Fri Apr 2 10:02 - 10:36 (00:33)
nagios pts/1 79.119.227.50 Fri Apr 2 09:35 - 13:18 (03:43)
nagios pts/1 91.194.84.177 Fri Apr 2 01:52 - 01:52 (00:00"
Could you help me out to try and understand how this has happened please as
I'm at a complete loss, if you need more info I will endeavour to get it for
you.
Thanks all

Nrpe.cfg and hosts allow are below.

######################################################
# LOG FACILITY
# The syslog facility that should be used for logging purposes.

log_facility=daemon

# PID FILE
# The name of the file in which the NRPE daemon should write it's process ID
# number.  The file is only written if the NRPE daemon is started by the
root
# user and is running in standalone mode.

pid_file=/var/run/nrpe.pid

# PORT NUMBER
# Port number we should wait for connections on.
# NOTE: This must be a non-priviledged port (i.e. > 1024).
# NOTE: This option is ignored if NRPE is running under either inetd or
xinetd

server_port=5666

# SERVER ADDRESS
# Address that nrpe should bind to in case there are more than one interface
# and you do not want nrpe to bind on all interfaces.
# NOTE: This option is ignored if NRPE is running under either inetd or
xinetd

#server_address=127.0.0.1

# NRPE USER
# This determines the effective user that the NRPE daemon should run as.  
# You can either supply a username or a UID.
# 
# NOTE: This option is ignored if NRPE is running under either inetd or
xinetd

nrpe_user=nagios

# NRPE GROUP
# This determines the effective group that the NRPE daemon should run as.  
# You can either supply a group name or a GID.
# 
# NOTE: This option is ignored if NRPE is running under either inetd or
xinetd

nrpe_group=nagios

# ALLOWED HOST ADDRESSES
# This is an optional comma-delimited list of IP address or hostnames 
# that are allowed to talk to the NRPE daemon.
#
# Note: The daemon only does rudimentary checking of the client's IP
# address.  I would highly recommend adding entries in your /etc/hosts.allow
# file to allow only the specified host to connect to the port
# you are running this daemon on.
#
# NOTE: This option is ignored if NRPE is running under either inetd or
xinetd

allowed_hosts=127.0.0.1
 
# COMMAND ARGUMENT PROCESSING
# This option determines whether or not the NRPE daemon will allow clients
# to specify arguments to commands that are executed.  This option only
works
# if the daemon was configured with the --enable-command-args configure
script
# option.  
#
# *** ENABLING THIS OPTION IS A SECURITY RISK! *** 
# Read the SECURITY file for information on some of the security
implications
# of enabling this variable.
#
# Values: 0=do not allow arguments, 1=allow command arguments

dont_blame_nrpe=0

# COMMAND PREFIX
# This option allows you to prefix all commands with a user-defined string.
# A space is automatically added between the specified prefix string and the
# command line from the command definition.
#
# *** THIS EXAMPLE MAY POSE A POTENTIAL SECURITY RISK, SO USE WITH CAUTION!
***
# Usage scenario: 
# Execute restricted commmands using sudo.  For this to work, you need to
add
# the nagios user to your /etc/sudoers.  An example entry for alllowing 
# execution of the plugins from might be:
#
# nagios          ALL=(ALL) NOPASSWD: /usr/lib/nagios/plugins/
#
# This lets the nagios user run all commands in that directory (and only
them)
# without asking for a password.  If you do this, make sure you don't give
# random users write access to that directory or its contents!

# command_prefix=/usr/bin/sudo 

# DEBUGGING OPTION
# This option determines whether or not debugging messages are logged to the
# syslog facility.
# Values: 0=debugging off, 1=debugging on

debug=0

# COMMAND TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# allow plugins to finish executing before killing them off.

command_timeout=60

# CONNECTION TIMEOUT
# This specifies the maximum number of seconds that the NRPE daemon will
# wait for a connection to be established before exiting. This is sometimes
# seen where a network problem stops the SSL being established even though
# all network sessions are connected. This causes the nrpe daemons to
# accumulate, eating system resources. Do not set this too low.

connection_timeout=300

# WEEK RANDOM SEED OPTION
# This directive allows you to use SSL even if your system does not have
# a /dev/random or /dev/urandom (on purpose or because the necessary patches
# were not applied). The random number generator will be seeded from a file
# which is either a file pointed to by the environment valiable $RANDFILE
# or $HOME/.rnd. If neither exists, the pseudo random number generator will
# be initialized and a warning will be issued.
# Values: 0=only seed from /dev/[u]random, 1=also seed from weak randomness

#allow_weak_random_seed=1

# INCLUDE CONFIG FILE
# This directive allows you to include definitions from an external config
file.

#include=<somefile.cfg>


# INCLUDE CONFIG DIRECTORY
# This directive allows you to include definitions from config files (with a
# .cfg extension) in one or more directories (with recursion).

#include_dir=<somedirectory>
#include_dir=<someotherdirectory>


# COMMAND DEFINITIONS
# Command definitions that this daemon will run.  Definitions
# are in the following format:
#
# command[<command_name>]=<command_line>
#
# When the daemon receives a request to return the results of <command_name>
# it will execute the command specified by the <command_line> argument.
#
# Unlike Nagios, the command line cannot contain macros - it must be
# typed exactly as it should be executed.
#
# Note: Any plugins that are used in the command lines must reside
# on the machine that this daemon is running on!  The examples below
# assume that you have plugins installed in a /usr/local/nagios/libexec
# directory.  Also note that you will have to modify the definitions below
# to match the argument format the plugins expect.  Remember, these are
# examples only!


# The following examples use hardcoded command arguments...

command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
command[check_load]=/usr/local/nagios/libexec/check_load -w 35,30,25 -c
50,45,40
command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p
/dev/hda1
command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10
-s Z
command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 1500 -c
2000 
command[check_disk1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p
/dev/sda3
command[check_disk2]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p
/dev/sda1
command[check_disk3]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p
tmpfscommand[check_local_swap]=/usr/local/nagios/libexec/check_swap -w 20%
-c 10%
command[check_local_swap]=/usr/local/nagios/libexec/check_swap -w 20% -c 10%


#command[check_users]=/usr/local/nagios/libexec/check_users -w $ARG1$ -c
$ARG2$
#command[check_load]=/usr/local/nagios/libexec/check_load -w $ARG1$ -c
$ARG2$
#command[check_disk]=/usr/local/nagios/libexec/check_disk -w $ARG1$ -c
$ARG2$ -p $ARG3$
#command[check_procs]=/usr/local/nagios/libexec/check_procs -w $ARG1$ -c
$ARG2$ -s $ARG3$


hosts.allow
#
# hosts.allow    This file describes the names of the hosts which are
#        allowed to use the local INET services, as decided
#        by the '/usr/sbin/tcpd' server.
#
nrpe: 17.0.0.1 xxx.27.117.xxx

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