Technical Tip: How to block 'http_agent="Dart/3.3 (dart:io)"'

[gsharma]

Description	This article describes how 'http_agent="Dart/3.3 (dart:io)"' can be blocked.
Scope	FortiWeb.
Solution	FortiWeb can block the traffic coming from 'http_agent="Dart/3.3 (dart:io)"'. This can be achieved by using Custom Policy. Steps can be performed as below: Navigate to Web Protection -> Advance Protection -> Custom Policy -> Custom Rule -> Create New and Give it name accordingly and select OK.                                                  After the rule is made, it is necessary to add Filter, so below the rule select Add Filter -> HTTP Header -> Select OK. Once it further opens the HTTP Header menu, Set the Header Field as 'Predefined Header name' and Header Name as 'User-Agent'. In Header Value Type set it as Regular Expression. Inside Header Value, fill the code as '^Dart\/\d+\.\d+ \(dart:io\)$' (this can be modified based on the http_agent in the traffic logs) and select OK.                                               Once the rule is created, they proceed with creating a Custom Policy and Call the rule in that policy. Once this is set up, call the Custom Policy in the required Web-protection profile, under Policy -> Web Protection Profile > Custom Policy, and select OK. If the issue is not resolved then reach out to the support helpline with the required config and logs. Related document: Custom Policy