Key concepts > Sequence of scans

Sequence of scans

FortiWeb appliances apply protection rules and perform protection profile scans in the following order of execution, which varies by whether you have applied a web protection profile. To understand the scan sequence, read from the top of the table (the first scan/action) towards the bottom (the last scan/action). Disabled scans are skipped.

To improve performance, block attackers using the earliest possible technique in the execution sequence and/or the least memory-consuming technique.

 

The blocking style varies by feature and configuration. For example, when detecting cookie poisoning, instead of resetting the TCP connection or blocking the HTTP request, you could log and remove the offending cookie. For details, see each specific feature.
Execution sequence (web protection profile)
Scan/action Involves
Request from client to server
TCP Connection Number Limit (TCP Flood Prevention) Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
Block Period Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
IP List * (individual client IP black list or white list) Source IP address of the client in the IP layer

Add X-Forwarded-For:

Add X-Real-IP:

Source IP address of the client in the HTTP layer
IP Reputation Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
Allow Known Search Engines Source IP address of the client in the IP layer
Geo IP Source IP address of the client in the IP layer
Add HSTS Header Strict-Transport-Security: header
Host (allowed/protected host name) Host:
Allow Method
  • Host:
  • URL in HTTP header
  • Request method in HTTP header
Real Browser Enforcement Tests whether the client is a web browser or automated tool.
Session Management
  • Cookie:
  • Session state
HTTP Request Limit/sec (HTTP Flood Prevention)
  • Cookie:
  • Session state
  • URL in the HTTP header
TCP Connection Number Limit (Malicious IP) Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)

HTTP Request Limit/sec (Shared IP)

or

HTTP Request Limit/sec (Shared IP) (HTTP Access Limit)

  • ID field of the IP header
  • Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
Brute Force Login
  • Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
  • URL in the HTTP header
HTTP Authentication Authorization:
Site Publish
  • Host:
  • URL of the request for the web application
Global White List
  • Cookie: cookiesession1
  • URL if /favicon.ico, AJAX URL parameters such as __LASTFOCUS, and others as updated by the FortiGuard Security Service
URL Access
  • Host:
  • URL in HTTP header
  • Source IP of the client in the IP header
Padding Oracle Protection
  • Host:
  • URL in HTTP header
  • Individually encrypted URL, cookie, or parameter
HTTP Protocol Constraints
  • Content-Length:
  • Parameter length
  • Body length
  • Header length
  • Header line length
  • Count of Range: header lines
  • Count of cookies
Cookie Poisoning Cookie:
Start Pages
  • Host:
  • URL in HTTP header
  • Session state
Page Access (page order)
  • Host:
  • URL in HTTP header
  • Session state
File Upload Restriction
  • Content-Length:
  • Content-Type:

in PUT and POST requests
Parameter Validation
  • Host:
  • URL in the HTTP header
  • Name, data type, and length
File Uncompress Content‑Type:
Web Cache
  • Host:
  • URL in the HTTP header
  • Size in kilobytes (KB) of each URL to cache
Cross Site Scripting, SQL Injection, Generic Attacks (attack signatures)
  • User-Agent: (Bad Robot)
  • Cookie:
  • Parameters in the URL, or the HTTP header or body
  • XML content in the HTTP body (if Enable XML Protocol Detection is enabled)
Hidden Fields Protection
  • Host:
  • URL in the HTTP header
  • Name, data type, and length of <input type="hidden">
Custom Rule
  • Source IP address of the client (depending on your configuration of X-header rules (see Defining your proxies, clients, & X-headers) this could be derived from either the SRC field in the IP header, or an HTTP header such as X-Forwarded-For: or X-Real-IP:)
  • URL in the HTTP header
  • HTTP header
  • Parameter in the URL, or the HTTP header or body
X-Forwarded-For X-Forwarded-For: in HTTP header
URL Rewriting (rewriting & redirects)
  • Host:
  • Referer:
  • Location:
  • URL in HTTP header
  • HTTP body
File Compress Content‑Type:
Client Certificate Forwarding Client’s personal certificate, if any, supplied during the SSL/TLS handshake
Auto-learning Any of the other features included by the auto-learning profile
Data Analytics
  • Source IP address of the client
  • URL in the HTTP header
  • Results from other scans
Reply from server to client
File Uncompress Content-Encoding:
Information Disclosure, Credit Card Detection
  • Server-identifying custom HTTP headers such as Server: and X-Powered-By: 
  • Credit card number in the body, and, if configured, Credit Card Detection Threshold
Hidden Fields Protection
  • Host:
  • URL in the HTTP header
  • Name, data type, and length of <input type="hidden">
Custom Rule
  • HTTP response code
  • Content Type:
URL Rewriting (rewriting)
  • Host:
  • Referer:
  • Location:
  • URL in HTTP header
  • HTTP body
File Compress Accept-Encoding:
Auto-learning Any of the other features included by the auto-learning profile
Data Analytics
  • Source IP address of the client
  • URL in the HTTP header
  • Results from other scans
* If a source IP is white listed, subsequent checks will be skipped.

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