Firewall events

Overview

Cloudflare is a global network designed to make everything you connect to the Internet secure, private, fast, and reliable.

In this documentation, you will learn how to collect and send Cloudflare Firewall events to Sekoia.io.

Benefit from SEKOIA.IO built-in rules and upgrade Cloudflare WAF events with the following detection capabilities out-of-the-box.

SEKOIA.IO x Cloudflare WAF events on ATT&CK Navigator

Bazar Loader DGA (Domain Generation Algorithm)

Detects Bazar Loader domains based on the Bazar Loader DGA

Effort: elementary

Burp Suite Tool Detected

Burp Suite is a cybersecurity tool. When used as a proxy service, its purpose is to intercept packets and modify them to send them to the server. Burp Collaborator is a network service that Burp Suite uses to help discover many kinds of vulnerabilities (vulnerabilities scanner)

Effort: intermediate

Nimbo-C2 User Agent

Nimbo-C2 Uses an unusual User-Agent format in its implants.

Effort: intermediate

Potential Azure AD Phishing Page (Adversary-in-the-Middle)

Detects an HTTP request to an URL typical of the Azure AD authentication flow, but towards a domain that is not one the legitimate Microsoft domains used for Azure AD authentication.

Effort: intermediate

Potential Bazar Loader User-Agents

Detects potential Bazar loader communications through the user-agent

Effort: elementary

Potential DNS Tunnel

Detects domain name which is longer than 95 characters. Long domain names are distinctive of DNS tunnels.

Effort: advanced

Potential Lemon Duck User-Agent

Detects LemonDuck user agent. The format used two sets of alphabetical characters separated by dashes, for example "User-Agent: Lemon-Duck-[A-Z]-[A-Z]".

Effort: elementary

SEKOIA.IO Intelligence Feed

Detect threats based on indicators of compromise (IOCs) collected by SEKOIA's Threat and Detection Research team.

Effort: elementary

Telegram Bot API Request

Detects suspicious DNS queries to api.telegram.org used by Telegram Bots of any kind

Effort: advanced

Event Categories

The following table lists the data source offered by this integration.

Data Source	Description
`Web application firewall logs`	Cloudflare protect web application with its web application firewall

In details, the following table denotes the type of events produced by this integration.

Name	Values
Kind	`event`
Category	`network`
Type	``

Event Samples

Find below few samples of events and how they are normalized by Sekoia.io.

403.jsonblock.json

{
    "message": "{\"Action\":\"block\",\"ClientIP\":\"113.206.179.28\",\"ClientRequestHost\":\"foo-bar-baz.xyz\",\"ClientRequestMethod\":\"GET\",\"ClientRequestPath\":\"/static/favicon.ico\",\"ClientRequestQuery\":\"\",\"Datetime\":1657630626219000000,\"EdgeResponseStatus\":403,\"RayID\":\"7299f155dda47d6b\"}",
    "event": {
        "action": "block",
        "kind": "event",
        "category": [
            "network"
        ],
        "dataset": "firewall-events",
        "type": [
            "denied"
        ]
    },
    "source": {
        "ip": "113.206.179.28",
        "address": "113.206.179.28"
    },
    "@timestamp": "2022-07-12T12:57:06.219000Z",
    "destination": {
        "domain": "foo-bar-baz.xyz",
        "address": "foo-bar-baz.xyz",
        "top_level_domain": "xyz",
        "registered_domain": "foo-bar-baz.xyz"
    },
    "http": {
        "request": {
            "method": "GET"
        },
        "response": {
            "status_code": 403
        }
    },
    "url": {
        "domain": "foo-bar-baz.xyz",
        "path": "/static/favicon.ico",
        "top_level_domain": "xyz",
        "registered_domain": "foo-bar-baz.xyz"
    },
    "observer": {
        "vendor": "Cloudflare",
        "type": "firewall"
    },
    "cloudflare": {
        "EdgeResponseStatus": 403,
        "RayID": "7299f155dda47d6b"
    },
    "related": {
        "hosts": [
            "foo-bar-baz.xyz"
        ],
        "ip": [
            "113.206.179.28"
        ]
    }
}

{
    "message": "{\"Action\":\"block\",\"ClientASN\":4562,\"ClientASNDescription\":\"PERFORMIVE\",\"ClientCountry\":\"us\",\"ClientIP\":\"10.6.12.26\",\"ClientIPClass\":\"noRecord\",\"ClientRefererHost\":\"\",\"ClientRefererPath\":\"\",\"ClientRefererQuery\":\"\",\"ClientRefererScheme\":\"\",\"ClientRequestHost\":\"foo-bar-baz.xyz\",\"ClientRequestMethod\":\"GET\",\"ClientRequestPath\":\"/.env\",\"ClientRequestProtocol\":\"HTTP/1.1\",\"ClientRequestQuery\":\"\",\"ClientRequestScheme\":\"http\",\"ClientRequestUserAgent\":\"Mozilla/5.0 (Linux; U; Android 4.4.2; en-US; HM NOTE 1W Build/KOT49H) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 UCBrowser/11.0.5.850 U3/0.8.0 Mobile Safari/534.30\",\"Datetime\":1669858111716000000,\"EdgeColoCode\":\"EWR\",\"EdgeResponseStatus\":403,\"Kind\":\"firewall\",\"MatchIndex\":0,\"Metadata\":{\"group\":\"cloudflare_specials\",\"rule_message\":\"Version Control - Information Disclosure\"},\"OriginResponseStatus\":0,\"OriginatorRayID\":\"00\",\"RayID\":\"77280bee38a6c461\",\"RuleID\":\"100016\",\"Source\":\"waf\"}",
    "event": {
        "action": "block",
        "kind": "event",
        "category": [
            "network"
        ],
        "dataset": "firewall-events",
        "type": [
            "denied"
        ],
        "module": "cloudflare.waf"
    },
    "source": {
        "ip": "10.6.12.26",
        "geo": {
            "country_name": "us"
        },
        "address": "10.6.12.26"
    },
    "@timestamp": "2022-12-01T01:28:31.716000Z",
    "destination": {
        "domain": "foo-bar-baz.xyz",
        "address": "foo-bar-baz.xyz",
        "top_level_domain": "xyz",
        "registered_domain": "foo-bar-baz.xyz"
    },
    "http": {
        "request": {
            "method": "GET"
        },
        "version": "HTTP/1.1",
        "response": {
            "status_code": 403
        }
    },
    "url": {
        "domain": "foo-bar-baz.xyz",
        "path": "/.env",
        "scheme": "http",
        "top_level_domain": "xyz",
        "registered_domain": "foo-bar-baz.xyz"
    },
    "user_agent": {
        "original": "Mozilla/5.0 (Linux; U; Android 4.4.2; en-US; HM NOTE 1W Build/KOT49H) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 UCBrowser/11.0.5.850 U3/0.8.0 Mobile Safari/534.30",
        "device": {
            "name": "XiaoMi HM NOTE 1W"
        },
        "name": "UC Browser",
        "version": "11.0.5",
        "os": {
            "name": "Android",
            "version": "4.4.2"
        }
    },
    "network": {
        "protocol": "HTTP/1.1"
    },
    "observer": {
        "vendor": "Cloudflare",
        "type": "firewall"
    },
    "cloudflare": {
        "ClientIPClass": "noRecord",
        "ClientRefererHost": "",
        "ClientRefererPath": "",
        "ClientRefererQuery": "",
        "ClientRefererScheme": "",
        "EdgeColoCode": "EWR",
        "EdgeResponseStatus": 403,
        "Kind": "firewall",
        "OriginResponseStatus": 0,
        "OriginatorRayID": "00",
        "RayID": "77280bee38a6c461",
        "source": "waf"
    },
    "related": {
        "hosts": [
            "foo-bar-baz.xyz"
        ],
        "ip": [
            "10.6.12.26"
        ]
    }
}

Extracted Fields

The following table lists the fields that are extracted, normalized under the ECS format, analyzed and indexed by the parser. It should be noted that infered fields are not listed.

Name	Type	Description
`@timestamp`	`date`	Date/time when the event originated.
`cloudflare.ClientIPClass`	`string`	The classification of the visitor’s IP address, possible values are: unknown
`cloudflare.ClientRefererHost`	`string`	The referer host
`cloudflare.ClientRefererPath`	`string`	The referer path requested by visitor
`cloudflare.ClientRefererQuery`	`string`	The referer query-string was requested by the visitor
`cloudflare.ClientRefererScheme`	`string`	The referer URL scheme requested by the visitor
`cloudflare.EdgeColoCode`	`string`	IATA airport code of data center that received the request
`cloudflare.EdgeResponseStatus`	`number`	HTTP status code returned by Cloudflare to the client
`cloudflare.Kind`	`string`	The dataset of the event
`cloudflare.OriginResponseStatus`	`number`	status returned by the origin server
`cloudflare.OriginatorRayID`	`string`	The RayID of the request that issued the challenge/jschallenge
`cloudflare.RayID`	`string`	ID of the request
`cloudflare.clientASNDescription`	`keyword`	The ASN of the visitor as string
`cloudflare.matchIndex`	`number`	Rules match index in the chain
`cloudflare.metadata`	`object`	Additional product-specific information. Metadata is organized in key:value pairs. Key and Value formats can vary by Cloudflare security product and can change over time
`cloudflare.source`	`keyword`	The Cloudflare security product triggered by this request
`destination.domain`	`keyword`	The domain name of the destination.
`event.action`	`keyword`	The action captured by the event.
`event.category`	`keyword`	Event category. The second categorization field in the hierarchy.
`event.dataset`	`keyword`	Name of the dataset.
`event.kind`	`keyword`	The kind of the event. The highest categorization field in the hierarchy.
`event.module`	`keyword`	Name of the module this data is coming from.
`http.request.bytes`	`long`	Total size in bytes of the request (body and headers).
`http.request.method`	`keyword`	HTTP request method.
`http.request.referrer`	`keyword`	Referrer for this HTTP request.
`http.response.status_code`	`long`	HTTP response status code.
`http.version`	`keyword`	HTTP version.
`network.protocol`	`keyword`	Application protocol name.
`observer.type`	`keyword`	The type of the observer the data is coming from.
`observer.vendor`	`keyword`	Vendor name of the observer.
`rule.description`	`keyword`	Rule description
`rule.id`	`keyword`	Rule ID
`rule.reference`	`keyword`	Rule reference URL
`rule.ruleset`	`keyword`	Rule ruleset
`source.as.number`	`long`	Unique number allocated to the autonomous system.
`source.geo.country_name`	`keyword`	Country name.
`source.ip`	`ip`	IP address of the source.
`source.port`	`long`	Port of the source.
`tls.cipher`	`keyword`	String indicating the cipher used during the current connection.
`tls.version_protocol`	`keyword`	Normalized lowercase protocol name parsed from original string.
`url.domain`	`keyword`	Domain of the url.
`url.path`	`wildcard`	Path of the request, such as "/search".
`url.query`	`keyword`	Query string of the request.
`url.scheme`	`keyword`	Scheme of the url.
`user_agent.original`	`keyword`	Unparsed user_agent string.

Configuration

Create the intake on Sekoia.io

Go to the intake page and create a new intake from the format Cloudflare.

Configure events forwarding on Cloudflare

Retrieve necessary information

First, you will have to retrieve configuration information. Connect to Cloudflare Console to collect the following :

Cloudflare API Token
- Go to My Profile, then on the left panel, click on API Tokens.
- Click on the Create Token button and select the Create Custom Token entry.
- Give a name to your token and set the following permissions:
Scope Group Level

Account Account Analytics Read

Account Logs Read

Account Logs Edit

Zone Logs Read

Zone Logs Edit
- If you want zerotrust logs you should also add:
Scope Group Level

Account Zero Trust Read

see the Cloudflare documentation
Cloudflare Zone ID :
- This information is specific to a Website.
- On the left panel, click on Websites and select the Website you want.
- On the right panel, there is an API section where you can retrieve the Zone ID.

Create a Logpush job

Configure a Logpush job with the following destination:

https://intake.sekoia.io/plain/batch?header_X-SEKOIAIO-INTAKE-KEY=<YOUR_INTAKE_KEY>

To do so, you can manage Logpush with cURL:

$ curl -X POST https://api.cloudflare.com/client/v4/zones/<CLOUDFLARE_ZONE_ID>/logpush/jobs \
-H "Authorization: Bearer <CLOUDFLARE_API_TOKEN>" \
-H "Content-Type: application/json" \
--data '{
    "dataset": "firewall_events",
    "enabled": true,
    "max_upload_bytes": 5000000,
    "max_upload_records": 1000,
    "logpull_options":"fields=Action,ClientASN,ClientASNDescription,ClientCountry,ClientIP,ClientIPClass,ClientRefererHost,ClientRefererPath,ClientRefererQuery,ClientRefererScheme,ClientRequestHost,ClientRequestMethod,ClientRequestPath,ClientRequestProtocol,ClientRequestQuery,ClientRequestScheme,ClientRequestUserAgent,Datetime,EdgeColoCode,EdgeResponseStatus,Kind,MatchIndex,Metadata,OriginResponseStatus,OriginatorRayID,RayID,RuleID,Source&timestamps=unix",
    "destination_conf": "https://intake.sekoia.io/plain/batch?header_X-SEKOIAIO-INTAKE-KEY=<YOUR_INTAKE_KEY>"
}' # (1)

will return

{
  "errors": [],
  "messages": [],
  "result": {
    "id": 147,
    "dataset": "firewall_events",
    "enabled": false,
    "name": "<DOMAIN_NAME>",
    "logpull_options": "fields=<LIST_OF_FIELDS>&timestamps=rfc3339",
    "destination_conf": "https://intake.sekoia.io/plain/batch?header_X-SEKOIAIO-INTAKE-KEY=<YOUR_INTAKE_KEY>",
    "last_complete": null,
    "last_error": null,
    "error_message": null
  },
  "success": true
}

Important

Replace :

<YOUR_INTAKE_KEY> with the Intake key you generated in the Create the intake on Sekoia.io step.
<CLOUDFLARE_API_TOKEN> with the API Token you generated
<CLOUDFLARE_ZONE_ID> with the Zone ID you grabbed

Useful Cloudflare API endpoints

On their documentation, Cloudflare provides a list API endpoints you can use. Find below some useful endpoints:

https://api.cloudflare.com/client/v4/zones/<ZONE_ID>/logpush/jobs/<JOB_ID> to verify the job you previously created is correct (you need to specify the JOB_ID)
https://api.cloudflare.com/client/v4/zones/<ZONE_ID>/logpush/datasets/<DATASET>/jobs to get all the jobs for a specific dataset (dns_log, firewalls_events or http_requests in our case)
https://api.cloudflare.com/client/v4/zones/<ZONE_ID>/logpush/jobs/<JOB_ID> to update a job if you noticed a mistake after the creation of the job (wrong fields, wrong SEKOIA API Key...)

Scope	Group	Level
Account	Account Analytics	Read
Account	Logs	Read
Account	Logs	Edit
Zone	Logs	Read
Zone	Logs	Edit