Hi all,

I'm having an issue with a brute force password attempt not being blocked 
and I'm not sure why, there are two rules as far as I can tell in the 
asterisk_rules.xml file, the latter should trigger when the former hits a 
certain number of failed attempts.

The 6210 rule is being hit and is being logged in the alerts.log file:

** Alert 1382974360.1666067: - syslog,asterisk,authentication_failed,
2013 Oct 28 15:32:40 demopbx->/var/log/messages
Rule: 6210 (level 5) -> 'Login session failed.'
Oct 28 15:32:38 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password

** Alert 1382974390.1666442: - syslog,asterisk,authentication_failed,
2013 Oct 28 15:33:10 demopbx->/var/log/messages
Rule: 6210 (level 5) -> 'Login session failed.'
Oct 28 15:33:09 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password

** Alert 1382974420.1666817: - syslog,asterisk,authentication_failed,
2013 Oct 28 15:33:40 demopbx->/var/log/messages
Rule: 6210 (level 5) -> 'Login session failed.'
Oct 28 15:33:39 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password

However nothing is being done about it as the multiple failed logins rule 
(6251) is not being triggered.


Not sure if this is useful, but when I try and test the rules by performing:

cat ossectest | /var/ossec/bin/ossec-logtest -v

I get:

    Trying rule: 6200 - Asterisk messages grouped.
       *Rule 6200 matched.
       *Trying child rules.
    Trying rule: 6201 - Asterisk notice messages grouped.
       *Rule 6201 matched.
       *Trying child rules.
    Trying rule: 6210 - Login session failed.
       *Rule 6210 matched.
       *Trying child rules.
    Trying rule: 6251 - Multiple failed logins.
    Trying rule: 40111 - Multiple authentication failures.

**Phase 3: Completed filtering (rules).
       Rule id: '6210'
       Level: '5'
       Description: 'Login session failed.'
**Alert to be generated.

ossectest contains:

Oct 28 15:02:17 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:18 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:19 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:20 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:21 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:22 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:23 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:24 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password
Oct 28 15:02:25 demopbx asterisk[3545]: NOTICE[3609]: chan_sip.c:27919 in 
handle_request_register: Registration from '"502" 
<sip:[email protected]>' failed for '85.64.90.98:5063' - Wrong password


Not sure if ossec-logtest tests the file as a whole or just takes them line 
by line.


I've tried altering the threshold and number of failed attempts before a 
block occurs because I noticed they're only trying a connection every 30 
seconds and wasn't sure if they were bypassing the checks like that, the 
two rules are as follows:

  <rule id="6210" level="5">
    <if_sid>6201</if_sid>
    <match>Wrong password</match>
    <description>Login session failed.</description>
    <group>authentication_failed,</group>
  </rule>

  <rule id="6251" level="10" frequency="2">
    <if_matched_sid>6210</if_matched_sid>
    <same_source_ip />
    <description>Multiple failed logins.</description>
  </rule>


I tried 6251 with a threshold of the default 300 and an increased 600.


Any help would be appreciated.



Best Regards

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