This patch updates the unix socket protocol. Messages send from
the server and the client have now a '\n' at the end. This allows
both sides to detect easily the end of a command.
As a side effect, this fixes the problem of long answer in
suricatasc. There is now a limit at the arbitrary value of 65536.
Backward compatility is preserved as a client with the older
version of the protocol can still connect to a Suricata with
version 2 of the protocol.
Under eve/alert, introduce a new metadata configuration
section. If no provided, or simply yes defaults will be used.
Otherwise this a map with fields that can be toggled on and
off. The defaults are:
outputs:
- eve-log:
types:
- alert:
metadata:
app-layer: true
flow: true
rule:
raw: false
metadata: true
To enable something that is disabled by default, or to disable
something that is enabled by default, only that key need to
be changed, everything else will keep its default value.
For SIEM analysis it is often useful to refer to the actual rules to
find out why a specific alert has been triggered when the signature
message does not convey enough information.
Turn on the new rule flag to include the rule text in eve alert output.
The feature is turned off by default.
With a rule like this:
alert dns $HOME_NET any -> 8.8.8.8 any (msg:"Google DNS server contacted"; sid:42;)
The eve alert output might look something like this (pretty-printed for
readability):
{
"timestamp": "2017-08-14T12:35:05.830812+0200",
"flow_id": 1919856770919772,
"in_iface": "eth0",
"event_type": "alert",
"src_ip": "10.20.30.40",
"src_port": 50968,
"dest_ip": "8.8.8.8",
"dest_port": 53,
"proto": "UDP",
"alert": {
"action": "allowed",
"gid": 1,
"signature_id": 42,
"rev": 0,
"signature": "Google DNS server contacted",
"category": "",
"severity": 3,
"rule": "alert dns $HOME_NET any -> 8.8.8.8 any (msg:\"Google DNS server contacted\"; sid:43;)"
},
"app_proto": "dns",
"flow": {
"pkts_toserver": 1,
"pkts_toclient": 0,
"bytes_toserver": 81,
"bytes_toclient": 0,
"start": "2017-08-14T12:35:05.830812+0200"
}
}
Feature #2020
Metadata of the signature can now conditionaly put in the alert
events. This will allow user to get more context about the events
generated by the alert.
detect-metadata: conditional parsing
Only parses metadata if an output module will use the information.
Patch also adds a unittest to check metadata is not parsed if not
asked to.
output-json-alert: optional output keys as array
Update rule metadata configuration to have an option to output
value as array. Also adds an option to log only a series of keys
as array. This is useful in the case of some ruleset where from
instance the `tag` key is used multiple time.
(Jason Ish) rule metadata: always log as lists
After review of rule metadata, we can't make assumptions
on what should be a list or not. So log everything as a list.
This patch updates the Signature structure so it contains the
metadata under a key value form.
Later patch will make that dictionary available in the events.
Both the suricata.yaml and eve configuration sections
included the eve-log section from suricata.yaml. First,
sync these up with the actual suricata.yaml then break
it out into its own file, so only one file needs to
be kept in sync with the actual configuration file.
By default log metadata.
Remove toggles for individual protocol types and just use a
single toggle to control including the app-layer with the
alert.
The metadata (currently app-layer and flow) can be disabled
by setting metadata to a falsey value, but its removed
from the default configuration (but wil be in docs)
Give traffic/id and traffic/label flowbits special handling
in the eve output. Instead of just logging them as flowbits,
give them their own top level object.
{
"traffic": {
"id": ["id0", "id1"],
"label": ["label0", "label1"]
}
}
This rule will match on the STREAM_3WHS_ACK_DATA_INJECT, that is
set if we're:
- in IPS mode
- get a data packet from the server
- that matches the exact SEQ/ACK expectations for the 3whs
The action of the rule is set to drop as the stream engine will drop.
So the rule action is actually not needed, but for consistency it
is drop.
If we have only seen the SYN and SYN/ACK of the 3whs, accept from
server data if it perfectly matches the SEQ/ACK expectations. This
might happen in 2 scenarios:
1. packet loss: if we lost the final ACK, we may get data that fits
this pattern (e.g. a SMTP EHLO message).
2. MOTS/MITM packet injection: an attacker can send a data packet
together with its SYN/ACK packet. The client due to timing almost
certainly gets the SYN/ACK before considering the data packet,
and will respond with the final ACK before processing the data
packet.
In IDS mode we will accept the data packet and rely on the reassembly
engine to warn us if the packet was indeed injected.
In IPS mode we will drop the packet. In the packet loss case we will
rely on retransmissions to get the session back up and running. For
the injection case we blocked this injection attempt.
The detect engine would bypass packets that are set as dropped. This
seems sane, as these packets are going to be dropped anyway.
However, it lead to the following corner case: stream events that
triggered the drop could not be matched on the rules. The packet
with the event wouldn't make it to the detect engine due to the bypass.
This patch changes the logic to not bypass DROP packets anymore.
Packets that are dropped by the stream engine will set the no payload
inspection flag, so avoid needless cost.
Eric Leblond
Jason Ish
Martin Natano
Victor Julien