ossec-logtest

ossec-logtest is the single most useful tool when working with ossec. This tool allows oneself to test and verify log files in the exact same way that ossec-anaylistd does.

Something ossec-logtest can help with:

  • Writing rules (Debugging your custom rules)
  • Troubleshooting false positives or false negatives

ossec-logtest accepts standard input for all log to test.

osssec-logtest argument options

-a

Analyze of input lines as if they are live events.

-c <config>

<config> is the path and filename to load in place of the default /var/ossec/etc/ossec.conf.

-D <dir>

This is the path that ossec-logtest will chroot to before it completes loading all rules, decoders, and lists and processing standard input.

-d

Print debug output to the terminal. This option can be used multiple times to increase the verbosity of the debug messages.

-h

Print the help message to the console.

-t

Test configuration. This will print file details on the ossec-anaylistd rules, decoders, and lists as they are loaded and the order they were processed.

-U <rule-id:alert-level:decoder-name>

This option will cause ossec-logtest to return with an exit status other then zero unless the last line tested matches the arguments passed.

Note

This only works for the last, line so passing many lines into ossec-logtest with this argument may not provide the desired results.

Note

This ossec-logtest code requires access to all ossec configuation files. This is a bug and will be corrected. It is documented in issue #`61 <https://bitbucket.org/jbcheng/ossec-hids/issue/61/ossec-logtest-must-be-used-with-a-full>`_

% echo "Aug 29 15:33:13 ns3 named[464]: client 217.148.39.3#1036: query (cache) denied" | sudo /var/ossec/bin/ossec-logtest -U 12108:0:named 2>&1 > /dev/null
% echo $?
0
% echo "Aug 29 15:33:13 ns3 XXXXXX[464]: client 217.148.39.3#1036: query (cache) denied" | sudo /var/ossec/bin/ossec-logtest -U 12108:0:named 2>&1 > /dev/null
% echo $?
3
-V

Print the Version and license message for OSSEC and ossec-logtest.

-v

Full output of all details and matches.

Note

This the key argument to troubleshoot a rule, decoder problem.

Note

This is argument was incorrectly displayed as running in the foreground in all version before version 2.5

Caveats

Some log formats will be processed differently than they appear in the log file. MySQL log files for instance will have ``MySQL log: `` prepended to the log message before analysis. If using ossec-logtest to test MySQL logs, please add this string to the beginning.

Example:

Given the following MySQL log message:

130218 12:07:52 [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. The statement is unsafe because it uses a LIMIT clause. This is unsafe because the set of rows included cannot be predicted. Statement: DELETE FROM `emailQueue` WHERE `emailQueueID` = '12207' LIMIT 1

The message that should be pasted into ossec-logtest is:

MySQL log: 130218 12:07:52 [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. The statement is unsafe because it uses a LIMIT clause. This is unsafe because the set of rows included cannot be predicted. Statement: DELETE FROM `emailQueue` WHERE `emailQueueID` = '12207' LIMIT 1

ossec-logtest example usage

Example 1: Testing standard rules

# echo "Aug 29 15:33:13 ns3 named[464]: client 217.148.39.3#1036: query (cache) denied" | /var/ossec/bin/ossec-logtest -f
2010/08/10 06:57:06 ossec-testrule: INFO: Reading decoder file loadables/decoders/00_decoders.xml.
2010/08/10 06:57:06 ossec-testrule: INFO: Reading decoder file loadables/decoders/50_named.xml.
2010/08/10 06:57:06 ossec-testrule: INFO: Reading decoder file loadables/decoders/50_pam.xml.
2010/08/10 06:57:06 ossec-testrule: INFO: Reading decoder file loadables/decoders/50_sshd.xml.
2010/08/10 06:57:06 ossec-testrule: INFO: Reading loading the lists file: 'loadables/lists/rfc1918-privateaddresses'
2010/08/10 06:57:06 ossec-testrule: INFO: Started (pid: 78828).
ossec-testrule: Type one log per line.



**Phase 1: Completed pre-decoding.
       full event: 'Aug 29 15:33:13 ns3 named[464]: client 217.148.39.3#1036: query (cache) denied'
       hostname: 'ns3'
       program_name: 'named'
       log: 'client 217.148.39.3#1036: query (cache) denied'

**Phase 2: Completed decoding.
       decoder: 'named'
       srcip: '217.148.39.3'

**Rule debugging:
    Trying rule: 1 - Generic template for all syslog rules.
       *Rule 1 matched.
       *Trying child rules.
    Trying rule: 30100 - Apache messages grouped.
    Trying rule: 7200 - Grouping of the arpwatch rules.
    Trying rule: 6200 - Asterisk messages grouped.
    Trying rule: 9600 - cimserver messages grouped.
    Trying rule: 4700 - Grouping of Cisco IOS rules.
    Trying rule: 3900 - Grouping for the courier rules.
    Trying rule: 9700 - Dovecot Messages Grouped.
    Trying rule: 11100 - Grouping for the ftpd rules.
    Trying rule: 9300 - Grouping for the Horde imp rules.
    Trying rule: 3600 - Grouping of the imapd rules.
    Trying rule: 3700 - Grouping of mailscanner rules.
    Trying rule: 3800 - Grouping of Exchange rules.
    Trying rule: 6300 - Grouping for the MS-DHCP rules.
    Trying rule: 6350 - Grouping for the MS-DHCP rules.
    Trying rule: 11500 - Grouping for the Microsoft ftp rules.
    Trying rule: 50100 - MySQL messages grouped.
    Trying rule: 12100 - Grouping of the named rules
       *Rule 12100 matched.
       *Trying child rules.
    Trying rule: 12107 - DNS update using RFC2136 Dynamic protocol.
    Trying rule: 12101 - Invalid DNS packet. Possibility of attack.
    Trying rule: 12109 - Named fatal error. DNS service going down.
    Trying rule: 12102 - Failed attempt to perform a zone transfer.
    Trying rule: 12103 - DNS update denied. Generally mis-configuration.
    Trying rule: 12104 - Log permission misconfiguration in Named.
    Trying rule: 12105 - Unexpected error while resolving domain.
    Trying rule: 12106 - DNS configuration error.
    Trying rule: 12108 - Query cache denied (maybe config error).
       *Rule 12108 matched.

**Phase 3: Completed filtering (rules).
       Rule id: '12108'
       Level: '4'
       Description: 'Query cache denied (maybe config error).'
       Info - Link: 'http://www.reedmedia.net/misc/dns/errors.html'
**Alert to be generated.

Example 2: Using OSSEC for the forensic analysis of log files

If you have one old log file that you want to check or if you are doing a forensics analysis of a box and wants to check the logs with OSSEC, we now have a solution too.

Let’s say you have a file /var/log/secure that you want to analyze with OSSEC. You need to use the ossec-logtest tool with the “-a” flag to reproduce the alerts:

# cat /var/log/secure | /var/ossec/bin/ossec-logtest -a

** Alert 1264788284.11: - syslog,sshd,authentication_success,
2010 Jan 29 14:04:44 enigma->stdin
Rule: 5715 (level 3) -> ‘SSHD authentication success.’
Src IP: a.b.2.15
User: dcid
Jan 15 10:25:01 enigma sshd[17594]: Accepted password for dcid from a.b.2.15 port 47526 ssh2

** Alert 1264788284.12: - syslog,sshd,authentication_success,
2010 Jan 29 14:04:44 enigma->stdin
Rule: 5715 (level 3) -> ‘SSHD authentication success.’
Src IP: 127.0.0.1
User: dcid
Jan 15 11:19:20 enigma sshd[18853]: Accepted publickey for dcid from 127.0.0.1 port 6725 ssh2

You will get the alerts just like you would at /var/ossec/logs/alerts.log. The benefit now is that you can pipe this output to ossec-reported to get a better view of what is going on:

# cat /var/log/secure | /var/ossec/bin/ossec-logtest -a |/var/ossec/bin/ossec-reported
Report completed. ==
————————————————
->Processed alerts: 522
->Post-filtering alerts: 522

Top entries for ‘Source ip’:
————————————————
89.200.169.170 |41 |
127.0.0.1 |33 |
83.170.106.142 |20 |
204.232.206.109 |16 |
..

Top entries for ‘Username’:
————————————————
root |247 |

Top entries for ‘Level’:
————————————————
Severity 5 |406 |
Severity 3 |41 |
Severity 10 |32 |

Top entries for ‘Group’:
————————————————
syslog |522 |
sshd |509 |
authentication_failed |369 |
invalid_login |146 |

Top entries for ‘Rule’:
————————————————
5716 - SSHD authentication failed. |223 |
5710 - Attempt to login using a non-existent.. |146 |
5715 - SSHD authentication success. |41 |
5702 - Reverse lookup error (bad ISP or atta.. |37 |

To get a report of all brute force attacks (for example) that scanned my box:

# cat /var/log/secure | /var/ossec/bin/ossec-logtest -a |/var/ossec/bin/ossec-reported -f group authentication_failures

Report completed. ==
————————————————
->Processed alerts: 522
->Post-filtering alerts: 25

Top entries for ‘Source ip’:
————————————————
83.170.106.142 |2 |
89.200.169.170 |2 |
114.255.100.163 |1 |
117.135.138.183 |1 |
124.205.62.36 |1 |
173.45.108.230 |1 |
200.182.99.59 |1 |
202.63.160.50 |1 |
210.21.225.202 |1 |
211.151.64.220 |1 |
213.229.70.12 |1 |
218.30.19.48 |1 |
221.12.12.3 |1 |
59.3.239.114 |1 |
61.168.227.12 |1 |
61.233.42.47 |1 |
67.43.61.80 |1 |
72.52.75.228 |1 |
77.245.148.196 |1 |
79.125.35.214 |1 |
85.21.83.170 |1 |
92.240.75.6 |1 |
94.198.49.185 |1 |

Top entries for ‘Username’:
————————————————
root |24 |

Top entries for ‘Level’:
————————————————
Severity 10 |25 |

Top entries for ‘Group’:
————————————————
authentication_failures |25 |
sshd |25 |
syslog |25 |

Top entries for ‘Location’:
————————————————
enigma->stdin |25 |

Top entries for ‘Rule’:
————————————————
5720 - Multiple SSHD authentication failures. |24 |
5712 - SSHD brute force trying to get access.. |1 |