Active rule currently published
This event is not caused by ASL. ASL is simply reporting when this occurs with Apache, and ASL neither causes this nor can it change this behavior in apache. Disabling this rule will only cause ASL to not report the event, it wont change apache behavior nor will disabling this prevent apache form rejecting these requests.
This rule reports when Apache has completely rejected a connection from a client, and Apache has determined the method used is Invalid. ASL does not cause this, this is simply a reporting rule, and disabling this rule will not prevent Apache from rejecting these invalid connections.
This rule does not shun the offending IP by default. Please see rule HIDS_30122 which will shun multiple 30113 events from the same IP within a period of time.
Certain DOS attacks use this method to use up all file handles in use on the system, and Heartbleed attacks ( See the Vuln_web_cve-2014-016 article for details) can generate this alert as well.
None. This rule simply reports when Apache has rejected the connection because it is using an invalid method.
None. Disabling this rule will have no effect on apache rejecting these connections. This event is not caused by ASL, and ASL can not change this behavior in apache.
Apache Log Examples
[error] [client 220.127.116.11] Invalid method in request /x16/x03/x01