2 - Official SSHD rules for OSSEC.
4 - Copyright (C) 2009 Trend Micro Inc.
7 - This program is a free software; you can redistribute it
8 - and/or modify it under the terms of the GNU General Public
9 - License (version 2) as published by the FSF - Free Software
12 - License details: http://www.ossec.net/en/licensing.html
16 <!-- SSHD messages -->
17 <group name="syslog,sshd,">
18 <rule id="5700" level="0" noalert="1">
19 <decoded_as>sshd</decoded_as>
20 <description>SSHD messages grouped.</description>
23 <rule id="5701" level="8">
25 <match>Bad protocol version identification</match>
26 <description>Possible attack on the ssh server </description>
27 <description>(or version gathering).</description>
30 <rule id="5702" level="5">
32 <match>^reverse mapping</match>
33 <regex>failed - POSSIBLE BREAK</regex>
34 <description>Reverse lookup error (bad ISP or attack).</description>
37 <rule id="5703" level="10" frequency="4" timeframe="360">
38 <if_matched_sid>5702</if_matched_sid>
39 <description>Possible breakin attempt </description>
40 <description>(high number of reverse lookup errors).</description>
43 <rule id="5704" level="4">
45 <match>fatal: Timeout before authentication for</match>
46 <description>Timeout while logging in (sshd).</description>
49 <rule id="5705" level="10" frequency="4" timeframe="360">
50 <if_matched_sid>5704</if_matched_sid>
51 <description>Possible scan or breakin attempt </description>
52 <description>(high number of login timeouts).</description>
55 <rule id="5706" level="6">
57 <match>Did not receive identification string from</match>
58 <description>SSH insecure connection attempt (scan).</description>
62 <rule id="5707" level="14">
64 <match>fatal: buffer_get_string: bad string</match>
65 <description>OpenSSH challenge-response exploit.</description>
66 <group>exploit_attempt,</group>
69 <rule id="5709" level="0">
71 <match>error: Could not get shadow information for NOUSER|</match>
72 <match>fatal: Read from socket failed: |error: ssh_msg_send: write|</match>
73 <match>^syslogin_perform_logout: </match>
74 <description>Useless SSHD message without an user/ip and context.</description>
77 <rule id="5710" level="5">
79 <match>illegal user|invalid user</match>
80 <description>Attempt to login using a non-existent user</description>
81 <group>invalid_login,authentication_failed,</group>
84 <rule id="5711" level="0">
86 <match>authentication failure; logname= uid=0 euid=0 tty=ssh|</match>
87 <match>input_userauth_request: invalid user|</match>
88 <match>PAM: User not known to the underlying authentication module for illegal user</match>
89 <description>Useless/Duplicated SSHD message without a user/ip.</description>
92 <rule id="5712" level="10" frequency="6" timeframe="120" ignore="60">
93 <if_matched_sid>5710</if_matched_sid>
94 <description>SSHD brute force trying to get access to </description>
95 <description>the system.</description>
97 <group>authentication_failures,</group>
100 <rule id="5713" level="6">
101 <if_sid>5700</if_sid>
102 <match>Corrupted check bytes on</match>
103 <description>Corrupted bytes on SSHD.</description>
106 <rule id="5714" level="14" timeframe="120" frequency="1">
107 <if_matched_sid>5713</if_matched_sid>
108 <match>Local: crc32 compensation attack</match>
109 <description>SSH CRC-32 Compensation attack</description>
110 <info type="cve">2001-0144</info>
111 <info type="link">http://www.securityfocus.com/bid/2347/info/</info>
112 <group>exploit_attempt,</group>
115 <rule id="5715" level="3">
116 <if_sid>5700</if_sid>
117 <match>^Accepted|authenticated.$</match>
118 <description>SSHD authentication success.</description>
119 <group>authentication_success,</group>
122 <rule id="5716" level="5">
123 <if_sid>5700</if_sid>
124 <match>^Failed|^error: PAM: Authentication</match>
125 <description>SSHD authentication failed.</description>
126 <group>authentication_failed,</group>
129 <rule id="5717" level="4">
130 <if_sid>5700</if_sid>
131 <match>error: Bad prime description in line</match>
132 <description>SSHD configuration error (moduli).</description>
135 <rule id="5718" level="5">
136 <if_sid>5700</if_sid>
137 <match>not allowed because</match>
138 <description>Attempt to login using a denied user.</description>
139 <group>invalid_login,</group>
142 <rule id="5719" level="10" frequency="6" timeframe="120" ignore="60">
143 <if_matched_sid>5718</if_matched_sid>
144 <description>Multiple access attempts using a denied user.</description>
147 <rule id="5720" level="10" frequency="6">
148 <if_matched_sid>5716</if_matched_sid>
150 <description>Multiple SSHD authentication failures.</description>
151 <group>authentication_failures,</group>
153 </group> <!-- SYSLOG, SSHD -->