[CentOS 8] 트립와이어(tripwire) 설치와 사용법

 

트립와이어(tripwire)는 시스템 파일 등 변조와 추가 등을 검사하는 무결성 검사 보안 도구 입니다. 무결성이란 정보(Data)가 인가된 사람만 접근 또는 변경이 가능하다는 것을 의미합니다. 의도치 않는 시스템 파일 변경 확인으로 해킹 징후를 탐지할 수 있어 보안 관리자 입장에서 유용한 도구 입니다. 이번 포스팅에서는 트립와이어(tripwire) 설치와 사용법에 대해 소개하겠습니다.

 

 

트립와이어(tripwire) 설치와 정책 설정

 

▷ 트립와이어 설치는 아래와 같이 진행합니다. 설치 전 epel 레포지토리를 설치 후 진행합니다.

 

# epel 레포지터리 추가
[root@localhost ~]# dnf -y install epel-release


# 트립와이어 설치
[root@localhost ~]# dnf --enablerepo=epel -y install tripwire


# 트립와이어에서 사용할 키 생성
[root@localhost ~]# tripwire-setup-keyfiles

----------------------------------------------
The Tripwire site and local passphrases are used to sign a  variety  of
files, such as the configuration, policy, and database files.

Passphrases should be at least 8 characters in length and contain  both
letters and numbers.

See the Tripwire manual for more information.

----------------------------------------------
Creating key files...

(When selecting a passphrase, keep in mind that good passphrases typically
have upper and lower case letters, digits and punctuation marks, and are
at least 8 characters in length.)

Enter the site keyfile passphrase:    # 키 패스워드 입력
Verify the site keyfile passphrase:   # 키 패스워드 입력
Generating key (this may take several minutes)...Key generation complete.

(When selecting a passphrase, keep in mind that good passphrases typically
have upper and lower case letters, digits and punctuation marks, and are
at least 8 characters in length.)

Enter the local keyfile passphrase:   # 키 패스워드 입력
Verify the local keyfile passphrase:  # 키 패스워드 입력
Generating key (this may take several minutes)...Key generation complete.

----------------------------------------------
Signing configuration file...
Please enter your site passphrase:    # 키 패스워드 입력
Wrote configuration file: /etc/tripwire/tw.cfg

A clear-text version of the Tripwire configuration file:
/etc/tripwire/twcfg.txt
has been preserved for your inspection.  It  is  recommended  that  you
move this file to a secure location and/or encrypt it in place (using a
tool such as GPG, for example) after you have examined it.


----------------------------------------------
Signing policy file...
Please enter your site passphrase:    # 키 패스워드 입력
Wrote policy file: /etc/tripwire/tw.pol

A clear-text version of the Tripwire policy file:
/etc/tripwire/twpol.txt
has been preserved for  your  inspection.  This  implements  a  minimal
policy, intended only to test  essential  Tripwire  functionality.  You
should edit the policy file to  describe  your  system,  and  then  use
twadmin to generate a new signed copy of the Tripwire policy.

Once you have a satisfactory Tripwire policy file, you should move  the
clear-text version to a secure location  and/or  encrypt  it  in  place
(using a tool such as GPG, for example).

Now run "tripwire --init" to enter Database Initialization  Mode.  This
reads the policy file, generates a database based on its contents,  and
then cryptographically signs the resulting  database.  Options  can  be
entered on the command line to specify which policy, configuration, and
key files are used  to  create  the  database.  The  filename  for  the
database can be specified as well. If no  options  are  specified,  the
default values from the current configuration file are used.



# 트립와이어 레포트 옵션 설정
[root@localhost ~]# vi /etc/tripwire/twcfg.txt

REPORTLEVEL = 3
->
REPORTLEVEL = 4

# 트립와이어 환경설정 생성
[root@localhost ~]# twadmin -m F -c /etc/tripwire/tw.cfg -S /etc/tripwire/site.key /etc/tripwire/twcfg.txt

# 정책 파일 최적화와 적용
[root@localhost ~]# vi /etc/tripwire/twpolmake.pl

# 아래 내용 추가

#!/usr/bin/perl
# Tripwire Policy File customize tool
# ----------------------------------------------------------------
# Copyright (C) 2003 Hiroaki Izumi
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
# ----------------------------------------------------------------
# Usage:
#     perl twpolmake.pl {Pol file}
# ----------------------------------------------------------------
#
$POLFILE=$ARGV[0];

open(POL,"$POLFILE") or die "open error: $POLFILE" ;
my($myhost,$thost) ;
my($sharp,$tpath,$cond) ;
my($INRULE) = 0 ;

while () {
    chomp;
    if (($thost) = /^HOSTNAME\s*=\s*(.*)\s*;/) {
        $myhost = `hostname` ; chomp($myhost) ;
        if ($thost ne $myhost) {
            $_="HOSTNAME=\"$myhost\";" ;
        }
    }
    elsif ( /^{/ ) {
        $INRULE=1 ;
    }
    elsif ( /^}/ ) {
        $INRULE=0 ;
    }
    elsif ($INRULE == 1 and ($sharp,$tpath,$cond) = /^(\s*\#?\s*)(\/\S+)\b(\s+->\s+.+)$/) {
        $ret = ($sharp =~ s/\#//g) ;
        if ($tpath eq '/sbin/e2fsadm' ) {
            $cond =~ s/;\s+(tune2fs.*)$/; \#$1/ ;
        }
        if (! -s $tpath) {
            $_ = "$sharp#$tpath$cond" if ($ret == 0) ;
        }
        else {
            $_ = "$sharp$tpath$cond" ;
        }
    }
    print "$_\n" ;
}
close(POL) ;


[root@localhost ~]# perl /etc/tripwire/twpolmake.pl /etc/tripwire/twpol.txt > /etc/tripwire/twpol.txt.new

[root@localhost ~]# twadmin -m P -c /etc/tripwire/tw.cfg -p /etc/tripwire/tw.pol -S /etc/tripwire/site.key /etc/tripwire/twpol.txt.new
Please enter your site passphrase:        # 키 패스워드 입력
Wrote policy file: /etc/tripwire/tw.pol


# DB 생성
[root@localhost ~]# tripwire -m i -s -c /etc/tripwire/tw.cfg
Please enter your local passphrase:       # 키 패스워드 입력

 

 

트립와이어(tripwire)를 이용한 점검과 레포트 확인

 

▷ 트립와이어를 이용한 점검 방법과 레포트 확인은 아래와 같습니다. 점검 이후 발생한 레포트로 현재 상태를 업데이트 합니다.

 

# 점검 시작
[root@localhost ~]# tripwire -m c -s -c /etc/tripwire/tw.cfg
Open Source Tripwire(R) 2.4.3.7 Integrity Check Report

Report generated by:          root
Report created on:            Fri 15 Jan 2021 09:00:14 AM KST
Database last updated on:     Never

===============================================================================
Report Summary:
===============================================================================

Host name:                    localhost.localdomain
Host IP address:              127.0.0.1
Host ID:                      None
Policy file used:             /etc/tripwire/tw.pol
Configuration file used:      /etc/tripwire/tw.cfg
Database file used:           /var/lib/tripwire/localhost.localdomain.twd
Command line used:            tripwire -m c -s -c /etc/tripwire/tw.cfg

===============================================================================
Rule Summary:
===============================================================================

-------------------------------------------------------------------------------
  Section: Unix File System
-------------------------------------------------------------------------------

  Rule Name                       Severity Level    Added    Removed  Modified
  ---------                       --------------    -----    -------  --------
  User binaries                   66                0        0        0
  Tripwire Binaries               100               0        0        0
  Libraries                       66                0        0        0
  File System and Disk Administraton Programs
                                  100               0        0        0
  Kernel Administration Programs  100               0        0        0
  Networking Programs             100               0        0        0
  System Administration Programs  100               0        0        0
  Hardware and Device Control Programs
                                  100               0        0        0
  System Information Programs     100               0        0        0
  Application Information Programs
                                  100               0        0        0
  (/sbin/rtmon)
  Critical Utility Sym-Links      100               0        0        0
  Shell Binaries                  100               0        0        0
  Critical system boot files      100               0        0        0
* Tripwire Data Files             100               1        0        0
  System boot changes             100               0        0        0
  OS executables and libraries    100               0        0        0
  Security Control                100               0        0        0
  Login Scripts                   100               0        0        0
  Critical configuration files    100               0        0        0
  Operating System Utilities      100               0        0        0
  Root config files               100               0        0        0
  Invariant Directories           66                0        0        0
  Temporary directories           33                0        0        0
  Critical devices                100               0        0        0
  (/proc/kcore)

Total objects scanned:  37734
Total violations found:  1

===============================================================================
Object Summary:
===============================================================================

-------------------------------------------------------------------------------
# Section: Unix File System
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
Rule Name: Tripwire Data Files (/var/lib/tripwire)
Severity Level: 100
-------------------------------------------------------------------------------

Added:
"/var/lib/tripwire/localhost.localdomain.twd"

===============================================================================
Error Report:
===============================================================================

No Errors

-------------------------------------------------------------------------------
*** End of report ***

Open Source Tripwire 2.4 Portions copyright 2000-2018 Tripwire, Inc.  Tripwire is a registered
trademark of Tripwire, Inc. This software comes with ABSOLUTELY NO WARRANTY;
for details use --version. This is free software which may be redistributed
or modified only under certain conditions; see COPYING for details.
All rights reserved.


# 레포트 저장 경로
[root@localhost ~]# ls -al /var/lib/tripwire/report
total 8
drwx------. 2 root root   55 Jan 15 09:00 .
drwx------. 3 root root   53 Jan 15 08:56 ..
-rw-r--r--. 1 root root 6614 Jan 15 09:00 localhost.localdomain-20210115-090014.twr


# 최근 검사 리포트로 DB 업데이트
[root@localhost ~]# tripwire -m u -a -s -c /etc/tripwire/tw.cfg -r /var/lib/tripwire/report/localhost.localdomain-20210115-090014.twr
Please enter your local passphrase:        # 키 패스워드 입력

 

 

 

 

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