12.1.2. Eve JSON Format


    "timestamp": "2009-11-24T21:27:09.534255",
    "event_type": "alert",
    "src_ip": "",
    "src_port": 1041,
    "dest_ip": "x.x.250.50",
    "dest_port": 80,
    "proto": "TCP",
    "alert": {
        "action": "allowed",
        "gid": 1,
        "signature_id" :2001999,
        "rev": 9,
        "signature": "ET MALWARE BTGrab.com Spyware Downloading Ads",
        "category": "A Network Trojan was detected",
        "severity": 1
} Common Section

All the JSON log types share a common structure:

{"timestamp":"2009-11-24T21:27:09.534255","event_type":"TYPE", ...tuple... ,"TYPE":{ ... type specific content ... }} Event types

The common part has a field “event_type” to indicate the log type.

"event_type":"TYPE" Event type: Alert Field action

Possible values: “allowed” and “blocked”



Action is set to “allowed” unless a rule used the “drop” action and Suricata is in IPS mode, or when the rule used the “reject” action.

It can also contain information about Source and Target of the attack in the alert.source and alert.target field it target keyword is used in the signature.

"alert": {
  "action": "allowed",
  "gid": 1,
  "signature_id": 1,
  "rev": 1,
  "app_proto": "http",
  "signature": "HTTP body talking about corruption",
  "severity": 3,
  "source": {
    "ip": "",
    "port": 36292
  "target": {
    "ip": "",
    "port": 80
  }, Event type: HTTP Fields

  • “hostname”: The hostname this HTTP event is attributed to
  • “url”: URL at the hostname that was accessed
  • “http_user_agent”: The user-agent of the software that was used
  • “http_content_type”: The type of data returned (ex: application/x-gzip)
  • “cookie”

In addition to these fields, if the extended logging is enabled in the suricata.yaml file the following fields are (can) also included:

  • “length”: The content size of the HTTP body
  • “status”: HTTP statuscode
  • “protocol”: Protocol / Version of HTTP (ex: HTTP/1.1)
  • “http_method”: The HTTP method (ex: GET, POST, HEAD)
  • “http_refer”: The referer for this action

In addition to the extended logging fields one can also choose to enable/add from 47 additional custom logging HTTP fields enabled in the suricata.yaml file. The additional fields can be enabled as following:

- eve-log:
    enabled: yes
    type: file #file|syslog|unix_dgram|unix_stream
    filename: eve.json
    # the following are valid when type: syslog above
    #identity: "suricata"
    #facility: local5
    #level: Info ## possible levels: Emergency, Alert, Critical,
                 ## Error, Warning, Notice, Info, Debug
      - alert
      - http:
          extended: yes     # enable this for extended logging information
          # custom allows additional http fields to be included in eve-log
          # the example below adds three additional fields when uncommented
          #custom: [Accept-Encoding, Accept-Language, Authorization]
          custom: [accept, accept-charset, accept-encoding, accept-language,
          accept-datetime, authorization, cache-control, cookie, from,
          max-forwards, origin, pragma, proxy-authorization, range, te, via,
          x-requested-with, dnt, x-forwarded-proto, accept-range, age,
          allow, connection, content-encoding, content-language,
          content-length, content-location, content-md5, content-range,
          content-type, date, etags, last-modified, link, location,
          proxy-authenticate, referrer, refresh, retry-after, server,
          set-cookie, trailer, transfer-encoding, upgrade, vary, warning,
          www-authenticate, x-flash-version, x-authenticated-user]

The benefits here of using the extended logging is to see if this action for example was a POST or perhaps if a download of an executable actually returned any bytes. Examples

Event with non-extended logging:

"http": {
    "hostname": "www.digip.org",
    "url" :"\/jansson\/releases\/jansson-2.6.tar.gz",
    "http_user_agent": "<User-Agent>",
    "http_content_type": "application\/x-gzip"

Event with extended logging:

"http": {
    "hostname": "direkte.vg.no",
    "http_user_agent": "<User-Agent>",
    "http_content_type": "application\/json",
    "http_refer": "http:\/\/www.vg.no\/",
    "http_method": "GET",
    "protocol": "HTTP\/1.1",
} Event type: DNS Fields

Outline of fields seen in the different kinds of DNS events:

  • “type”: Indicating DNS message type, can be “answer” or “query”.
  • “id”: <needs explanation>
  • “rrname”: Resource Record Name (ex: a domain name)
  • “rrtype”: Resource Record Type (ex: A, AAAA, NS, PTR)
  • “rdata”: Resource Data (ex. IP that domain name resolves to)
  • “ttl”: Time-To-Live for this resource record Examples

Example of a DNS query for the IPv4 address of “twitter.com” (resource record type ‘A’):

"dns": {
    "type": "query",
    "id": 16000,
    "rrname": "twitter.com",

Example of a DNS answer with an IPv4 (resource record type ‘A’) return:

"dns": {
    "type": "answer",
    "rrname": "twitter.com",
    "rdata": ""
} Event type: TLS Fields

  • “subject”: The subject field from the TLS certificate
  • “issuer”: The issuer field from the TLS certificate
  • “session_resumed”: This field has the value of “true” if the TLS session was resumed via a session id. If this field appears, “subject” and “issuer” do not appear, since a TLS certificate is not seen.

If extended logging is enabled the following fields are also included:

  • “serial”: The serial number of the TLS certificate
  • “fingerprint”: The (SHA1) fingerprint of the TLS certificate
  • “sni”: The Server Name Indication (SNI) extension sent by the client
  • “version”: The SSL/TLS version used
  • “notbefore”: The NotBefore field from the TLS certificate
  • “notafter”: The NotAfter field from the TLS certificate

In addition to this, custom logging also allows the following fields:

  • “certificate”: The TLS certificate base64 encoded
  • “chain”: The entire TLS certificate chain base64 encoded Examples

Example of regular TLS logging:

"tls": {
    "subject": "C=US, ST=California, L=Mountain View, O=Google Inc, CN=*.google.com",
    "issuerdn": "C=US, O=Google Inc, CN=Google Internet Authority G2"

Example of regular TLS logging for resumed sessions:

"tls": {
    "session_resumed": true

Example of extended TLS logging:

"tls": {
    "subject": "C=US, ST=California, L=Mountain View, O=Google Inc, CN=*.google.com",
    "issuerdn": "C=US, O=Google Inc, CN=Google Internet Authority G2",
    "serial": "0C:00:99:B7:D7:54:C9:F6:77:26:31:7E:BA:EA:7C:1C",
    "fingerprint": "8f:51:12:06:a0:cc:4e:cd:e8:a3:8b:38:f8:87:59:e5:af:95:ca:cd",
    "sni": "calendar.google.com",
    "version": "TLS 1.2",
    "notbefore": "2017-01-04T10:48:43",
    "notafter": "2017-03-29T10:18:00"

Example of certificate logging using TLS custom logging (subject, sni, certificate):

"tls": {
    "subject": "C=US, ST=California, L=Mountain View, O=Google Inc, CN=*.googleapis.com
    "sni": "www.googleapis.com",
    "certificate": "MIIE3TCCA8WgAwIBAgIIQPsvobRZN0gwDQYJKoZIhvcNAQELBQAwSTELMA [...]"