[ossec-list] Re: SSH brute force and firewall drop.

["Daniel Cid" <daniel.cid@xxxxxxxxx>]

Hi Fletch,

Which operating system are you using? The logs are not well formatted, so ossec
is not parsing them correctly.

They start with the date/time, followed by the program name (with the
weird brackets
around them):

Jul 16 21:37:18 [sshd(pam_unix)] authentication failure; logname=
uid=0 euid=0 tty=ssh ruser= rhost=remoteIP
Jul 16 21:37:16 [sshd] error: PAM: Authentication failure for illegal
user fred from  remoteIP


Ossec expects the date/time followed by hostname and followed by the
program name
without brackets (notmal syslog message):
Dec 13 09:19:09 hostname sshd(pam_unix)


We would need to change some of the decoders to support this format...


Thanks,

--
Daniel B. Cid
dcid ( at ) ossec.net



On 7/16/07, Fletch Hasues <hasues@xxxxxxxxx> wrote:
> Greetings,
>   I am trying to configure a host to prevent access via firewall drop by
> using the rules that I see firing, and lately those are of multiple
> authentication failures.  So far, I have not been able to get active
> response to make use of the firewall-drop.sh script to block access.  if I
> login with a false user and try to login, I see the logs noting that this is
> happening, and it does send out e-mail, but the active-response fails to
> firewall the IP.
>
>  Received From: myhost->/var/log/everything/current
> Rule: 40111 fired (level 10) -> "Multiple authentication failures."
> Portion of the log(s):
>
>  Jul 16 21:37:18 [sshd(pam_unix)] authentication failure; logname= uid=0
> euid=0 tty=ssh ruser= rhost=remoteIP
> Jul 16 21:37:16 [sshd] error: PAM: Authentication failure for illegal user
> fred from  remoteIP
> Jul 16 21:37:14 [sshd(pam_unix)] authentication failure; logname= uid=0
> euid=0 tty=ssh ruser= rhost= remoteIP
> Jul 16 21:37:10 [sshd] error: PAM: Authentication failure for illegal user
> fred from remoteIP
>
>
> My ossec.conf file appears as:
>
>  <ossec_config>
>   <global>
>     <email_notification>yes</email_notification>
>     <email_to>myemail</email_to>
>     <smtp_servermysmtp</smtp_server>
>     <email_from> ossecm@myhost</email_from>
>   </global>
>
>   <rules>
>     <include>rules_config.xml</include>
>     <include>pam_rules.xml</include>
>     <include>sshd_rules.xml</include>
>     <include>telnetd_rules.xml</include>
>     <include>syslog_rules.xml</include>
>     <include>arpwatch_rules.xml</include>
>     <include>symantec-av_rules.xml</include>
>     <include>pix_rules.xml</include>
>     <include>named_rules.xml</include>
>     <include>smbd_rules.xml</include>
>     <include>vsftpd_rules.xml</include>
>     <include>pure-ftpd_rules.xml</include>
>     <include>proftpd_rules.xml</include>
>     <include>ms_ftpd_rules.xml</include>
>     <include>hordeimp_rules.xml</include>
>     <include>vpopmail_rules.xml</include>
>     <include>web_rules.xml</include>
>     <include>apache_rules.xml</include>
>     <include>ids_rules.xml</include>
>     <include>squid_rules.xml</include>
>     <include>firewall_rules.xml</include>
>     <include>netscreenfw_rules.xml</include>
>     <include>postfix_rules.xml</include>
>     <include>sendmail_rules.xml</include>
>     <include>imapd_rules.xml</include>
>     <include>mailscanner_rules.xml</include>
>     <include>ms-exchange_rules.xml</include>
>     <include>racoon_rules.xml</include>
>     <include>vpn_concentrator_rules.xml</include>
>     <include>spamd_rules.xml</include>
>     <include>msauth_rules.xml</include>
>     <!-- <include>policy_rules.xml</include> -->
>     <include>attack_rules.xml</include>
>     <include>zeus_rules.xml</include>
>     <include>ossec_rules.xml</include>
>     <include>local_rules.xml</include>
>   </rules>
>
>   <syscheck>
>     <!-- Frequency that syscheck is executed - default to every 6 hours -->
>     <frequency>21600</frequency>
>
>     <!-- Directories to check  (perform all possible verifications) -->
>     <directories
> check_all="yes">/etc,/usr/bin,/usr/sbin</directories>
>     <directories check_all="yes">/bin,/sbin</directories>
>
>     <!-- Files/directories to ignore -->
>     <ignore>/etc/mtab</ignore>
>     <ignore>/etc/mnttab</ignore>
>     <ignore>/etc/hosts.deny</ignore>
>     <ignore>/etc/mail/statistics</ignore>
>     <ignore>/etc/random-seed</ignore>
>     <ignore>/etc/adjtime</ignore>
>     <ignore>/etc/httpd/logs</ignore>
>     <ignore>/etc/utmpx</ignore>
>     <ignore>/etc/wtmpx</ignore>
>     <ignore>/etc/cups/certs</ignore>
>
>     <!-- Windows files to ignore -->
>     <ignore>C:\WINDOWS/System32/LogFiles</ignore>
>     <ignore>C:\WINDOWS/Debug</ignore>
>     <ignore>C:\WINDOWS/WindowsUpdate.log</ignore>
>     <ignore>C:\WINDOWS/iis6.log</ignore>
>     <ignore>C:\WINDOWS/system32/wbem/Logs</ignore>
>     <ignore>C:\WINDOWS/system32/wbem/Repository</ignore>
>     <ignore>C:\WINDOWS/Prefetch</ignore>
>     <ignore>C:\WINDOWS/PCHEALTH/HELPCTR/DataColl</ignore>
>     <ignore>C:\WINDOWS/SoftwareDistribution</ignore>
>     <ignore>C:\WINDOWS/Temp</ignore>
>     <ignore>C:\WINDOWS/system32/config</ignore>
>     <ignore>C:\WINDOWS/system32/spool</ignore>
>     <ignore>C:\WINDOWS/system32/CatRoot</ignore>
>   </syscheck>
>
>   <rootcheck>
>
> <rootkit_files>/var/ossec/etc/shared/rootkit_files.txt</rootkit_files>
>
> <rootkit_trojans>/var/ossec/etc/shared/rootkit_trojans.txt</rootkit_trojans>
>   </rootcheck>
>
>   <global>
>     <white_list>127.0.0.1</white_list>
>     <white_list>^localhost.localdomain$</white_list>
>     <white_list> 192.168.74.1</white_list>
>     <white_list>192.168.74.85</white_list>
>     <white_list>192.168.74.15 </white_list>
>   </global>
>
>   <alerts>
>     <log_alert_level>1</log_alert_level>
>     <email_alert_level>7</email_alert_level>
>   </alerts>
>
>   <command>
>     <name>host-deny</name>
>     <executable>host-deny.sh</executable>
>     <expect>srcip</expect>
>     <timeout_allowed>yes</timeout_allowed>
>   </command>
>
>   <command>
>     <name>firewall-drop</name>
>     <executable>firewall-drop.sh</executable>
>     <expect>srcip</expect>
>     <timeout_allowed>yes</timeout_allowed>
>   </command>
>
>   <command>
>     <name>disable-account</name>
>     <executable>disable-account.sh</executable>
>     <expect>user</expect>
>     <timeout_allowed>yes</timeout_allowed>
>   </command>
>
>   <command>
>     <name>route-null</name>
>     <executable>route-null.sh</executable>
>     <expect>srcip</expect>
>     <timeout_allowed>yes</timeout_allowed>
>   </command>
>
>
>   <!-- Active Response Config -->
>   <active-response>
>     <!-- This response is going to execute the host-deny
>        - command for every event that fires a rule with
>        - level (severity) >= 6.
>        - The IP is going to be blocked for  600 seconds.
>       -->
>     <command>host-deny</command>
>     <location>local</location>
>     <level>6</level>
>     <timeout>600</timeout>
>   </active-response>
>
>   <active-response>
>     <!-- Firewall Drop response. Block the IP for
>        - 600 seconds on the firewall (iptables,
>        - ipfilter, etc).
>       -->
>     <command>firewall-drop</command>
>     <location>local</location>
>     <level>6</level>
>     <timeout>600</timeout>
>   </active-response>
>
>   <!-- Files to monitor (localfiles) -->
>     <localfile>
>       <location>/var/log/everything/current</location>
>       <log_format>syslog</log_format>
>     </localfile>
> </ossec_config>
>
> What am I missing?  Anyone?
>
> Fletch
>
>