<!-- @(#) $Id: sshd_rules.xml,v 1.22 2010/12/19 14:50:14 ddp Exp $
  -  Official SSHD rules for OSSEC.
  -
  -  Copyright (C) 2009-2011 Trend Micro Inc.
  -  All rights reserved.
  -
  -  This program is a free software; you can redistribute it
  -  and/or modify it under the terms of the GNU General Public
  -  License (version 2) as published by the FSF - Free Software
  -  Foundation.
  -
  -  License details: http://www.ossec.net/en/licensing.html
  -->
  

<!-- SSHD messages -->
<group name="syslog,sshd,">
  <rule id="5700" level="0" noalert="1">
    <decoded_as>sshd</decoded_as>
    <description>SSHD messages grouped.</description>
  </rule>
              
  <rule id="5701" level="8">
    <if_sid>5700</if_sid>
    <match>Bad protocol version identification</match>
    <description>Possible attack on the ssh server </description>
    <description>(or version gathering).</description>
  </rule>

  <rule id="5702" level="5">
    <if_sid>5700</if_sid>
    <match>^reverse mapping</match>
    <regex>failed - POSSIBLE BREAK</regex>
    <description>Reverse lookup error (bad ISP or attack).</description>
  </rule>

  <rule id="5703" level="10" frequency="4" timeframe="360">
    <if_matched_sid>5702</if_matched_sid>
    <description>Possible breakin attempt </description>
    <description>(high number of reverse lookup errors).</description>
  </rule>

  <rule id="5704" level="4">
    <if_sid>5700</if_sid>
    <match>fatal: Timeout before authentication for</match>
    <description>Timeout while logging in (sshd).</description>
  </rule>

  <rule id="5705" level="10" frequency="4" timeframe="360">
    <if_matched_sid>5704</if_matched_sid>
    <description>Possible scan or breakin attempt </description>
    <description>(high number of login timeouts).</description>
  </rule>

  <rule id="5706" level="6">
    <if_sid>5700</if_sid>
    <match>Did not receive identification string from</match>
    <description>SSH insecure connection attempt (scan).</description>
    <group>recon,</group>
  </rule>

  <rule id="5707" level="14">
    <if_sid>5700</if_sid>
    <match>fatal: buffer_get_string: bad string</match>
    <description>OpenSSH challenge-response exploit.</description>
    <group>exploit_attempt,</group>
  </rule>

  <rule id="5709" level="0">
    <if_sid>5700</if_sid>
    <match>error: Could not get shadow information for NOUSER|</match>
    <match>fatal: Read from socket failed: |error: ssh_msg_send: write|</match>
    <match>^syslogin_perform_logout: |^pam_succeed_if(sshd:auth): error retrieving information about user|can't verify hostname: getaddrinfo</match>
    <description>Useless SSHD message without an user/ip and context.</description>
  </rule>
  
  <rule id="5710" level="5">
    <if_sid>5700</if_sid>
    <match>illegal user|invalid user</match>
    <description>Attempt to login using a non-existent user</description>
    <group>invalid_login,authentication_failed,</group>
  </rule>

  <rule id="5711" level="0">
    <if_sid>5700</if_sid>
    <match>authentication failure; logname= uid=0 euid=0 tty=ssh|</match>
    <match>input_userauth_request: invalid user|</match>
    <match>PAM: User not known to the underlying authentication module for illegal user|</match>
    <match>error retrieving information about user</match>
    <description>Useless/Duplicated SSHD message without a user/ip.</description>
  </rule>

  <rule id="5712" level="10" frequency="6" timeframe="120" ignore="60">
    <if_matched_sid>5710</if_matched_sid>
    <description>SSHD brute force trying to get access to </description>
    <description>the system.</description>
    <same_source_ip />
    <group>authentication_failures,</group>
  </rule>

  <rule id="5713" level="6">
    <if_sid>5700</if_sid>
    <match>Corrupted check bytes on</match>
    <description>Corrupted bytes on SSHD.</description>  
  </rule>
  
  <rule id="5714" level="14" timeframe="120" frequency="1">
    <if_matched_sid>5713</if_matched_sid>
    <match>Local: crc32 compensation attack</match>
    <description>SSH CRC-32 Compensation attack</description>
    <info type="cve">2001-0144</info>
    <info type="link">http://www.securityfocus.com/bid/2347/info/</info>
    <group>exploit_attempt,</group>
  </rule>  

  <rule id="5715" level="3">
    <if_sid>5700</if_sid>
    <match>^Accepted|authenticated.$</match>
    <description>SSHD authentication success.</description>
    <group>authentication_success,</group>
  </rule>

  <rule id="5716" level="5">
    <if_sid>5700</if_sid>
    <match>^Failed|^error: PAM: Authentication</match>
    <description>SSHD authentication failed.</description>
    <group>authentication_failed,</group>
  </rule>  

  <rule id="5717" level="4">
    <if_sid>5700</if_sid>
    <match>error: Bad prime description in line</match>
    <description>SSHD configuration error (moduli).</description>
  </rule>

  <rule id="5718" level="5">
    <if_sid>5700</if_sid>
    <match>not allowed because</match>
    <description>Attempt to login using a denied user.</description>
    <group>invalid_login,</group>
  </rule>
                      
  <rule id="5719" level="10" frequency="6" timeframe="120" ignore="60">
    <if_matched_sid>5718</if_matched_sid>
    <description>Multiple access attempts using a denied user.</description>
    <group>invalid_login,</group>
  </rule>
  
  <rule id="5720" level="10" frequency="6">
    <if_matched_sid>5716</if_matched_sid>
    <same_source_ip />
    <description>Multiple SSHD authentication failures.</description>
    <group>authentication_failures,</group>
  </rule>                                       

  <rule id="5721" level="0">
    <if_sid>5700</if_sid>
    <match>Received disconnect from</match>
    <description>System disconnected from sshd.</description>
  </rule>

  <rule id="5722" level="0">
    <if_sid>5700</if_sid>
    <match>Connection closed</match>
    <description>ssh connection closed.</description>
  </rule>

  <rule id="5723" level="0">
    <if_sid>5700</if_sid>
    <match>error: buffer_get_bignum2_ret: negative numbers not supported</match>
    <info>This maybe a bad key in authorized_keys.</info>
    <description>SSHD key error.</description>
  </rule>

  <rule id="5724" level="0">
    <if_sid>5700</if_sid>
    <match>fatal: buffer_get_bignum2: buffer error</match>
    <info>This error may relate to ssh key handling.</info>
    <description>SSHD key error.</description>
  </rule>

  <rule id="5725" level="0">
    <if_sid>5700</if_sid>
    <match>fatal: Write failed: Host is down</match>
    <description>Host ungracefully disconnected.</description>
  </rule>

  <rule id="5726" level="5">
    <if_sid>5700</if_sid>
    <match>error: PAM: Module is unknown for</match>
    <description>Unknown PAM module, PAM misconfiguration.</description>
  </rule>

  <rule id="5727" level="0">
    <if_sid>5700</if_sid>
    <match>failed: Address already in use.</match>
    <description>Attempt to start sshd when something already bound to the port.</description>
  </rule>

  <rule id="5728" level="4">
    <if_sid>5700</if_sid>
    <match>Authentication service cannot retrieve user credentials</match>
    <info>May be related to PAM module errors.</info>
    <description>Authentication services were not able to retrieve user credentials.</description>
    <group>authentication_failed</group>
  </rule>

  <rule id="5729" level="0">
    <if_sid>5700</if_sid>
    <match>debug1: attempt</match>
    <description>Debug message.</description>
  </rule>

  <rule id="5730" level="4">
    <if_sid>5700</if_sid>
    <regex>error: connect to \S+ port \d+ failed: Connection refused</regex>
    <description>SSHD is not accepting connections.</description>
  </rule>

  <rule id="5731" level="6">
    <if_sid>5700</if_sid>
    <match>AKASSH_Version_Mapper1.</match>
    <description>SSH Scanning.</description>
    <group>recon,</group>
  </rule>

  <rule id="5732" level="0">
    <if_sid>5700</if_sid>
    <match>error: connect_to </match>
    <description>Possible port forwarding failure.</description>
  </rule>

  <rule id="5733" level="0">
    <if_sid>5700</if_sid>
    <match>Invalid credentials</match>
    <description>User entered incorrect password.</description>
    <group>authentication_failures,</group>
  </rule>

  <rule id="5734" level="0">
    <if_sid>5700</if_sid>
    <match>Could not load host key</match>
    <description>sshd could not load one or more host keys.</description>
    <info>This may be related to an upgrade to OpenSSH.</info>
  </rule>

  <rule id="5735" level="0">
    <if_sid>5700</if_sid>
    <match>Write failed: Broken pipe</match>
    <description>Failed write due to one host disappearing.</description>
  </rule>

  <rule id="5736" level="0">
    <if_sid>5700</if_sid>
    <match>^error: setsockopt SO_KEEPALIVE: Connection reset by peer$|</match>
    <match>^error: accept: Software caused connection abort$</match>
    <description>Connection reset or aborted.</description>
  </rule>

  <rule id="5737" level="5">
    <if_sid>5700</if_sid>
    <match>^fatal: Cannot bind any address.$</match>
    <description>sshd cannot bind to configured address.</description>
  </rule>

  <rule id="5738" level="5">
    <if_sid>5700</if_sid>
    <match>set_loginuid failed opening loginuid$</match>
    <description>pam_loginuid could not open loginuid.</description>
    <group>authentication_failed,</group>
  </rule>

</group> <!-- SYSLOG, SSHD -->

<!-- EOF -->
