Configure GraphQL malicious query protection
Use the Cloudflare GraphQL API to gather data about your GraphQL API’s current usage and configure Cloudflare’s GraphQL malicious query protection to log or block malicious queries.
Introduction
Query size is defined as the number of terminal fields (leaves) in the query, whereas query depth is the deepest level at which a leaf is present. For example, the size of this query will be reported as 4 (terminalField[1-4] all contribute to this counter)
, and the depth will be reported as 3 (terminalField3 and terminalField4 are at depth level 3)
.
GraphQL query{ terminalField1 nonTerminalField1(filter: 123) { terminalField2 nonTerminalField2 { terminalField3 terminalField4 } }
}
Gather GraphQL statistics
Using the new apiGatewayGraphqlQueryAnalyticsGroups
node in the Cloudflare GraphQL API, you can retrieve apiGatewayGraphqlQuerySize
and apiGatewayGraphqlQueryDepth
dimensions.
GraphQL queryquery ApiGatewayGraphqlQueryAnalytics($zoneTag: string, $datetimeStart: Time, $datetimeEnd: Time) { viewer { zones(filter: {zoneTag: $zoneTag}) { apiGatewayGraphqlQueryAnalyticsGroups(limit: 100, orderBy: [apiGatewayGraphqlQuerySize_DESC, apiGatewayGraphqlQueryDepth_DESC], filter: {datetime_geq:$datetimeStart, datetime_leq:$datetimeEnd}) { count dimensions { apiGatewayGraphqlQuerySize apiGatewayGraphqlQueryDepth } } } }
}
With the above query, you will get the following response:
Response{ "data": { "viewer": { "zones": [ { "apiGatewayGraphqlQueryAnalyticsGroups": [ { "count": 10, "dimensions": { "apiGatewayGraphqlQueryDepth": 1, "apiGatewayGraphqlQuerySize": 11 } }, { "count": 10, "dimensions": { "apiGatewayGraphqlQueryDepth": 1, "apiGatewayGraphqlQuerySize": 2 } } ] } ] } }, "errors": null
}
In the response example, Cloudflare observed 10 requests with depth 1 and size 11, and 10 requests with depth 1 and size 2 in the selected timeframe.
Analyze GraphQL statistics
You can use the response to compute percentiles across the attributes and set a threshold on what is allowed. For example, you can use a simple heuristic like 1.5 * p99
for query size or depth.
Here is a simple Python script that will report query size and depth p-levels given the GraphQL API response output above (as a JSON file):
Python script#!/usr/bin/env python3 import jsonimport numpy as npimport argparse parser = argparse.ArgumentParser()parser.add_argument("--response", help="Path to the API JSON response file with the apiGatewayGraphqlQueryAnalyticsGroups node", required=True)args = parser.parse_args()
with open(args.response) as f: query_sizes = np.array([], dtype=np.uint16) query_depths = np.array([], dtype=np.uint8) data = json.load(f)['data']['viewer']['zones'][0]['apiGatewayGraphqlQueryAnalyticsGroups'] for datapoint in data: query_sizes = np.append(query_sizes, [datapoint['dimensions']['apiGatewayGraphqlQuerySize']] * datapoint['count']) query_depths = np.append(query_depths, [datapoint['dimensions']['apiGatewayGraphqlQueryDepth']] * datapoint['count']) quantiles = [0.99, 0.95, 0.75, 0.5] print('\n'.join([f"Query size {int(q * 100)}th percentile is {v}" for q, v in zip(quantiles, np.quantile(query_sizes, quantiles))])) print('\n'.join([f"Query depth {int(q * 100)}th percentile is {v}" for q, v in zip(quantiles, np.quantile(query_depths, quantiles))]))
With the above query, you will get the following output:
Example output./calculator.py --response=response.jsonQuery size 99th percentile is 11.0Query size 95th percentile is 11.0Query size 75th percentile is 11.0Query size 50th percentile is 6.5Query depth 99th percentile is 1.0Query depth 95th percentile is 1.0Query depth 75th percentile is 1.0Query depth 50th percentile is 1.0
Set limits on incoming GraphQL queries
API Shield customers now have three new fields available in custom rules:
cf.api_gateway.graphql.query_size
describes the size of a GraphQL query.cf.api_gateway.graphql.query_depth
describes the depth of a GraphQL query.cf.api_gateway.graphql.parsed_successfully
describes whether Cloudflare was able to parse the query. Presently, we run best-effort parsing, meaning we might not be able to parse some valid queries. This means that you must use aand cf.api_gateway.graphql.parsed_successfully
filter in your custom rules when deploying GraphQL security rules.
For example, you can deploy the following rule via the API or the dashboard to block queries that are deeply nested but ask for a few fields.
Custom rule example(cf.api_gateway.graphql.query_size < 3 and cf.api_gateway.graphql.query_depth > 15 and cf.api_gateway.graphql.parsed_successfully)