Azure Web Application Firewall monitoring and logging

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Azure Web Application Firewall (WAF) monitoring and logging are provided through logging and integration with Azure Monitor and Azure Monitor logs.

Azure Monitor

WAF with FrontDoor log is integrated with Azure Monitor. Azure Monitor allows you to track diagnostic information including WAF alerts and logs. You can configure WAF monitoring within the Front Door resource in the portal under the Diagnostics tab or through the Azure Monitor service directly.

From Azure portal, go to Front Door resource type. From Monitoring/Metrics tab on the left, you can add WebApplicationFirewallRequestCount to track number of requests that match WAF rules. Custom filters can be created based on action types and rule names.

WAFMetrics

Logs and diagnostics

WAF with Front Door provides detailed reporting on each threat it detects. Logging is integrated with Azure Diagnostics logs and alerts are recorded in a json format. These logs can be integrated with Azure Monitor logs.

WAFDiag

FrontdoorAccessLog logs all requests. FrontdoorWebApplicationFirewallLog logs any request that matches a WAF rule having the below schema:

Property Description
Action Action taken on the request
ClientIp The IP address of the client that made the request. If there was an X-Forwarded-For header in the request, then the Client IP is picked from the header field.
ClientPort The IP port of the client that made the request.
Details Additional details on the matched request
matchVariableName: http parameter name of the request matched, for example, header names
matchVariableValue: values that triggered the match
Host The host header of the matched request
Policy The name of the WAF policy that the request matched.
PolicyMode Operations mode of the WAF policy. Possible values are "Prevention" and "Detection"
RequestUri Full URI of the matched request.
RuleName The name of the WAF rule that the request matched.
SocketIp The source IP address seen by WAF. This IP address is based on TCP session, independent of any request headers.
TrackingReference The unique reference string that identifies a request served by Front Door, also sent as X-Azure-Ref header to the client. Required for searching details in the access logs for a specific request.

The following query example returns WAF logs on blocked requests:

AzureDiagnostics
| where ResourceType == "FRONTDOORS" and Category == "FrontdoorWebApplicationFirewallLog"
| where action_s == "Block"

Here is an example of a logged request in WAF log:

{
    "time":  "2020-06-09T22:32:17.8376810Z",
    "category": "FrontdoorWebApplicationFirewallLog",
    "operationName": "Microsoft.Network/FrontDoorWebApplicationFirewallLog/Write",
    "properties":
    {
        "clientIP":"xxx.xxx.xxx.xxx",
        "clientPort":"52097",
        "socketIP":"xxx.xxx.xxx.xxx",
        "requestUri":"https://wafdemofrontdoorwebapp.azurefd.net:443/?q=%27%20or%201=1",
        "ruleName":"Microsoft_DefaultRuleSet-1.1-SQLI-942100",
        "policy":"WafDemoCustomPolicy",
        "action":"Block",
        "host":"wafdemofrontdoorwebapp.azurefd.net",
        "trackingReference":"08Q3gXgAAAAAe0s71BET/QYwmqtpHO7uAU0pDRURHRTA1MDgANjMxNTAwZDAtOTRiNS00YzIwLTljY2YtNjFhNzMyOWQyYTgy",
        "policyMode":"prevention",
        "details":
            {
            "matches":
                [{
                "matchVariableName":"QueryParamValue:q",
                "matchVariableValue":"' or 1=1"
                }]
            }
     }
}

The following example query returns AccessLogs entries:

AzureDiagnostics
| where ResourceType == "FRONTDOORS" and Category == "FrontdoorAccessLog"

Here is an example of a logged request in Access log:

{
"time": "2020-06-09T22:32:17.8383427Z",
"category": "FrontdoorAccessLog",
"operationName": "Microsoft.Network/FrontDoor/AccessLog/Write",
 "properties":
    {
    "trackingReference":"08Q3gXgAAAAAe0s71BET/QYwmqtpHO7uAU0pDRURHRTA1MDgANjMxNTAwZDAtOTRiNS00YzIwLTljY2YtNjFhNzMyOWQyYTgy",
    "httpMethod":"GET",
    "httpVersion":"2.0",
    "requestUri":"https://wafdemofrontdoorwebapp.azurefd.net:443/?q=%27%20or%201=1",
    "requestBytes":"715",
    "responseBytes":"380",
    "userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4157.0 Safari/537.36 Edg/85.0.531.1",
    "clientIp":"xxx.xxx.xxx.xxx",
    "socketIp":"xxx.xxx.xxx.xxx",
    "clientPort":"52097",
    "timeTaken":"0.003",
    "securityProtocol":"TLS 1.2",
    "routingRuleName":"WAFdemoWebAppRouting",
    "rulesEngineMatchNames":[],
    "backendHostname":"wafdemowebappuscentral.azurewebsites.net:443",
    "sentToOriginShield":false,
    "httpStatusCode":"403",
    "httpStatusDetails":"403",
    "pop":"SJC",
    "cacheStatus":"CONFIG_NOCACHE"
    }
}

Next steps