Cloudflare 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.

Vendor: Cloudflare
Plan: Defend Prime
Supported environment: SaaS
Detection based on: Telemetry
Supported application or feature: Web application firewall logs

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...)

Raw Events Samples

In this section, you will find examples of raw logs as generated natively by the source. These examples are provided to help integrators understand the data format before ingestion into Sekoia.io. It is crucial for setting up the correct parsing stages and ensuring that all relevant information is captured.

403block

{
    "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"
}

{
    "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"
}

Detection section

The following section provides information for those who wish to learn more about the detection capabilities enabled by collecting this intake. It includes details about the built-in rule catalog, event categories, and ECS fields extracted from raw events. This is essential for users aiming to create custom detection rules, perform hunting activities, or pivot in the events page.

The following Sekoia.io built-in rules match the intake Cloudflare WAF events. This documentation is updated automatically and is based solely on the fields used by the intake which are checked against our rules. This means that some rules will be listed but might not be relevant with the intake.

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

Correlation Potential DNS Tunnel

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

Effort: advanced

Covenant Default HTTP Beaconing

Detects potential Covenant communications through the user-agent and specific urls

Effort: intermediate

Cryptomining

Detection of domain names potentially related to cryptomining activities.

Effort: master

Discord Suspicious Download

Discord is a messaging application. It allows users to create their own communities to share messages and attachments. Those attachments have little to no overview and can be downloaded by almost anyone, which has been abused by attackers to host malicious payloads.

Effort: intermediate

Dynamic DNS Contacted

Detect communication with dynamic dns domain. This kind of domain is often used by attackers. This rule can trigger false positive in non-controlled environment because dynamic dns is not always malicious.

Effort: master

EvilProxy Phishing Domain

Detects subdomains potentially generated by the EvilProxy adversary-in-the-middle phishing platform. Inspect the other subdomains of the domain to identify the landing page, and determine if the user submitted credentials. This rule has a small percentage of false positives on legitimate domains.

Effort: intermediate

Exfiltration Domain

Detects traffic toward a domain flagged as a possible exfiltration vector.

Effort: master

Koadic MSHTML Command

Detects Koadic payload using MSHTML module

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

Potential LokiBot User-Agent

Detects potential LokiBot communications through the user-agent

Effort: intermediate

Remote Access Tool Domain

Detects traffic toward a domain flagged as a Remote Administration Tool (RAT).

Effort: master

Remote Monitoring and Management Software - AnyDesk

Detect artifacts related to the installation or execution of the Remote Monitoring and Management tool AnyDesk.

Effort: master

Remote Monitoring and Management Software - Atera

Detect artifacts related to the installation or execution of the Remote Monitoring and Management tool Atera.

Effort: master

SEKOIA.IO Intelligence Feed

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

Effort: elementary

Sekoia.io EICAR Detection

Detects observables in Sekoia.io CTI tagged as EICAR, which are fake samples meant to test detection.

Effort: master

Suspicious TOR Gateway

Detects suspicious TOR gateways. Gateways are often used by the victim to pay and decrypt the encrypted files without installing TOR. Tor intercepts the network traffic from one or more apps on user’s computer, usually the user web browser, and shuffles it through a number of randomly-chosen computers before passing it on to its destination. This disguises user location, and makes it harder for servers to pick him/her out on repeat visits, or to tie together separate visits to different sites, this making tracking and surveillance more difficult. Before a network packet starts its journey, user’s computer chooses a random list of relays and repeatedly encrypts the data in multiple layers, like an onion. Each relay knows only enough to strip off the outermost layer of encryption, before passing what’s left on to the next relay in the list.

Effort: advanced

TOR Usage Generic Rule

Detects TOR usage globally, whether the IP is a destination or source. TOR is short for The Onion Router, and it gets its name from how it works. TOR intercepts the network traffic from one or more apps on user’s computer, usually the user web browser, and shuffles it through a number of randomly-chosen computers before passing it on to its destination. This disguises user location, and makes it harder for servers to pick him/her out on repeat visits, or to tie together separate visits to different sites, this making tracking and surveillance more difficult. Before a network packet starts its journey, user’s computer chooses a random list of relays and repeatedly encrypts the data in multiple layers, like an onion. Each relay knows only enough to strip off the outermost layer of encryption, before passing what’s left on to the next relay in the list.

Effort: master

Telegram Bot API Request

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

Effort: advanced

WAF Block Rule

Detects when one of WAF rule blocked an HTTP request

Effort: master

WAF Correlation Block actions

Detection of multiple block actions (more than 30) triggered by the same source by WAF detection rules

Effort: master

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	``
Category	`network`
Type	``

Transformed Events Samples after Ingestion

This section demonstrates how the raw logs will be transformed by our parsers. It shows the extracted fields that will be available for use in the built-in detection rules and hunting activities in the events page. Understanding these transformations is essential for analysts to create effective detection mechanisms with custom detection rules and to leverage the full potential of the collected data.

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

{
    "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",
        "category": [
            "network"
        ],
        "dataset": "firewall-events",
        "module": "cloudflare.waf",
        "type": [
            "denied"
        ]
    },
    "@timestamp": "2022-12-01T01:28:31.716000Z",
    "cloudflare": {
        "ClientIPClass": "noRecord",
        "ClientRefererHost": "",
        "ClientRefererPath": "",
        "ClientRefererQuery": "",
        "ClientRefererScheme": "",
        "EdgeColoCode": "EWR",
        "EdgeResponseStatus": 403,
        "Kind": "firewall",
        "OriginResponseStatus": 0,
        "OriginatorRayID": "00",
        "RayID": "77280bee38a6c461",
        "source": "waf"
    },
    "destination": {
        "address": "foo-bar-baz.xyz",
        "domain": "foo-bar-baz.xyz",
        "registered_domain": "foo-bar-baz.xyz",
        "top_level_domain": "xyz"
    },
    "http": {
        "request": {
            "method": "GET"
        },
        "response": {
            "status_code": 403
        },
        "version": "HTTP/1.1"
    },
    "network": {
        "protocol": "HTTP/1.1"
    },
    "observer": {
        "type": "firewall",
        "vendor": "Cloudflare"
    },
    "related": {
        "hosts": [
            "foo-bar-baz.xyz"
        ],
        "ip": [
            "10.6.12.26"
        ]
    },
    "source": {
        "address": "10.6.12.26",
        "geo": {
            "country_name": "us"
        },
        "ip": "10.6.12.26"
    },
    "url": {
        "domain": "foo-bar-baz.xyz",
        "path": "/.env",
        "registered_domain": "foo-bar-baz.xyz",
        "scheme": "http",
        "top_level_domain": "xyz"
    },
    "user_agent": {
        "device": {
            "name": "XiaoMi HM NOTE 1W"
        },
        "name": "UC Browser",
        "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",
        "os": {
            "name": "Android",
            "version": "4.4.2"
        },
        "version": "11.0.5"
    }
}

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.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.

For more information on the Intake Format, please find the code of the Parser, Smart Descriptions, and Supported Events here.

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