2 Copyright (C) 2009 Trend Micro Inc.
6 --- Rules Classification ---
11 The rules are classified in multiple levels. From the lowest (00) to the maximum
12 level 16. Some levels are not used right now. Other levels can be added between
15 **The rules will be read from the highest to the lowest level. **
17 00 - Ignored - No action taken. Used to avoid false positives. These rules
18 are scanned before all the others. They include events with no
21 02 - System low priority notification - System notification or
22 status messages. They have no security relevance.
23 03 - Successful/Authorized events - They include successful login attempts,
24 firewall allow events, etc.
25 04 - System low priority error - Errors related to bad configurations or
26 unused devices/applications. They have no security relevance and
27 are usually caused by default installations or software testing.
28 05 - User generated error - They include missed passwords, denied
29 actions, etc. By itself they have no security relevance.
30 06 - Low relevance attack - They indicate a worm or a virus that have
31 no affect to the system (like code red for apache servers, etc).
32 They also include frequently IDS events and frequently errors.
33 07 - "Bad word" matching. They include words like "bad", "error", etc.
34 These events are most of the time unclassified and may have
35 some security relevance.
36 08 - First time seen - Include first time seen events. First time
37 an IDS event is fired or the first time an user logged in.
38 If you just started using OSSEC HIDS these messages will
39 probably be frequently. After a while they should go away.
40 It also includes security relevant actions (like the starting
41 of a sniffer or something like that).
42 09 - Error from invalid source - Include attempts to login as
43 an unknown user or from an invalid source. May have security
44 relevance (specially if repeated). They also include errors
45 regarding the "admin" (root) account.
46 10 - Multiple user generated errors - They include multiple bad
47 passwords, multiple failed logins, etc. They may indicate an
48 attack or may just be that a user just forgot his credentials.
49 11 - Integrity checking warning - They include messages regarding
50 the modification of binaries or the presence of rootkits (by
51 rootcheck). If you just modified your system configuration
52 you should be fine regarding the "syscheck" messages. They
53 may indicate a successful attack. Also included IDS events
54 that will be ignored (high number of repetitions).
55 12 - High importancy event - They include error or warning messages
56 from the system, kernel, etc. They may indicate an attack against
57 a specific application.
58 13 - Unusual error (high importance) - Most of the times it matches a
59 common attack pattern.
60 14 - High importance security event. Most of the times done with
61 correlation and it indicates an attack.
62 15 - Severe attack - No chances of false positives. Immediate
63 attention is necessary.
68 -We can specify groups for specific rules. It's used for active
69 response reasons and for correlation.
70 - We currently use the following groups:
73 - authentication_success
74 - authentication_failed
89 http://www.ossec.net/en/manual.html#rules