FortiOS 6 – Security profiles overview

Security profiles overview

The FortiGate line combines a number of security features to protect your network from threats. As a whole, these features, when included in a single Fortinet security appliance, are referred to as Security Profiles.

This overview addresses the following topics:

l Traffic inspection l Content inspection and filtering l Security profile components l Security profiles/lists/sensors

Firewall policies limit access, and while this and similar features are a vital part of securing your network, they are not covered in this discussion of Security Profiles.

FortiOS 5.4 no longer supports FortiClient 5.0.

FortiOS 5.4.1 supports only FortiClient 5.4.1. Be sure to upgrade managed FortiClients before upgrading the FortiGate to 5.4.1.

FortiOS 5.2 can support FortiClient 5.0, but only if the FortiGate upgraded to FortiOS 5.2. Customers need to purchase a FortiClient 5.4 subscription-based FortiClient license.

Traffic inspection

When the FortiGate unit examines network traffic one packet at a time for IPS signatures, it is performing traffic analysis. This is unlike content analysis where the traffic is buffered until files, email messages, web pages, and other files are assembled and examined as a whole.

DoS policies use traffic analysis by keeping track of the type and quantity of packets, as well as their source and destination addresses.

Application control uses traffic analysis to determine which application generated the packet.

Although traffic inspection doesn’t involve taking packets and assembling files they are carrying, the packets themselves can be split into fragments as they pass from network to network. These fragments are reassembled by the FortiGate unit before examination.

No two networks are the same and few recommendations apply to all networks. This topic offers suggestions on how you can use the FortiGate unit to help secure your network against content threats.

IPS signatures

IPS signatures can detect malicious network traffic. For example, the Code Red worm attacked a vulnerability in the Microsoft IIS web server. Your FortiGate’s IPS system can detect traffic attempting to exploit this vulnerability. IPS may also detect when infected systems communicate with servers to receive instructions.

Traffic inspection

IPS recommendations

  • Enable IPS scanning at the network edge for all services. l Use FortiClient endpoint IPS scanning for protection against threats that get into your network.
  • Subscribe to FortiGuard IPS Updates and configure your FortiGate unit to receive push updates. This will ensure you receive new IPS signatures as soon as they are available.
  • Your FortiGate unit includes IPS signatures written to protect specific software titles from DoS attacks. Enable the signatures for the software you have installed and set the signature action to Block.
  • You can view these signatures by going to Security Profiles > Intrusion Prevention and selecting the [View IPS Signatures] link in the right-hand corner of the window. l Because it is critical to guard against attacks on services that you make available to the public, configure IPS signatures to block matching signatures. For example, if you have a web server, configure the action of web server signatures to Block.

Suspicious traffic attributes

Network traffic itself can be used as an attack vector or a means to probe a network before an attack. For example, SYN and FIN flags should never appear together in the same TCP packet. The SYN flag is used to initiate a TCP session while the FIN flag indicates the end of data transmission at the end of a TCP session.

The FortiGate unit has IPS signatures that recognize abnormal and suspicious traffic attributes. The SYN/FIN combination is one of the suspicious flag combinations detected in TCP traffic by the TCP.BAD.FLAGS signature.

The signatures that are created specifically to examine traffic options and settings, begin with the name of the traffic type they are associated with. For example, signatures created to examine TCP traffic have signature names starting with TCP.

Application control

While applications can often be blocked by the ports they use, application control allows convenient management of all supported applications, including those that do not use set ports. Application control recommendations

l Some applications behave in an unusual manner in regards to application control. For more information, see Application considerations on page 128. l By default, application control allows the applications not specified in the application control list. For high security networks, you may want to change this behavior so that only the explicitly allowed applications are permitted.

SSL/SSH inspection

Regular web filtering can be circumvented by using https:// instead of http://. By enabling this feature, the FortiGate can filter traffic that is using the HTTPS protocol. This sort of analysis is some times referred to as deep scanning.

Deep Inspection works along the following lines: If your FortiGate unit has the correct chipset it will be able to scan SSL encrypted traffic in the same way that regular traffic can be scanned. The FortiGate firewall will essentially receive the traffic on behalf of the client and open up the encrypted traffic. Once it is finished it reContent inspection and filtering

encrypts the traffic and sends it on to its intended recipient. It is very similar to a man-in-the-middle attack. By enabling this feature, it allows the FortiGate firewall to filter on traffic that is using the SSL encrypted protocol.

The encrypted protocols that can be inspected are:


Before the invention of SSL inspection, scanning regular web traffic can be circumvented by using the prefix https:// instead of http:// in the URL. SSL inspection prevents this circumvention. However, because when the encrypted traffic is decrypted it has to be re-encrypted with the FortiGate’s certificate rather than the original certificate it can cause errors because the name on the certificate does not match the name on the web site.

At one point deep inspection was something that was either turned on or off. Now individual deep inspection profiles can be created depending on the requirements of the policy. Depending on the Inspection Profile, you can:

  • Configure which CA certificate will be used to decrypt the SSL encrypted traffic. l Configure which SSL protocols will be inspected. l Configure which ports will be associated with which SSL protocols for the purpose of inspection.
  • Configure which websites will be exempt from SSL inspection l Configure whether or not to allow invalid SSL certificates. l Configure whether or not SSH traffic will be inspected.

Web rating overrides

This feature allows you to override the FortiGuard Web Filtering. This option allows users to change the rating for a website and control access to the site without affecting the rest of the sites in the original category. More information can be found in Overriding FortiGuard website categorization.

Web profile overrides

This feature allows administrators to grant temporary access to sites that are otherwise blocked by a web filter profile. The temporary access can be granted to a user, user group, or source IP address. The time limit can be set in days, hours, or minutes. See the section on Web Profile Overrides for more information.

Content inspection and filtering

When the FortiGate unit buffers the packets containing files, email messages, web pages, and other similar files for reassembly before examining them, it is performing content inspection. Traffic inspection, on the other hand, is accomplished by the FortiGate unit examining individual packets of network traffic as they are received.

No two networks are the same and few recommendations apply to all networks. This topic offers suggestions on how you can use the FortiGate unit to help secure your network against threats to content. Be sure to understand the effects of the changes before using the suggestions.


The FortiGate antivirus scanner can detect viruses and other malicious payloads used to infect machines. The FortiGate unit performs deep content inspection. To prevent attempts to disguise viruses, the antivirus scanner will reassemble fragmented files and uncompress content that has been compressed. Patented Compact Pattern Recognition Language (CPRL) allows further inspection for common patterns, increasing detection rates of virus variations in the future.

AntiVirus recommendations

  • Enable antivirus scanning at the network edge for all services. l Use FortiClient endpoint antivirus scanning for protection against threats that get into your network.
  • Subscribe to FortiGuard AntiVirus Updates and configure your FortiGate unit to receive push updates. This will ensure that new antivirus signatures are loaded onto your FortiGate as soon as they are available.
  • Enable the Extended Virus Database if your FortiGate unit supports it.
  • Examine antivirus logs periodically. Take particular notice of repeated detections. For example, repeated virus detection in SMTP traffic could indicate a system on your network is infected and is attempting to contact other systems to spread the infection using a mass mailer.
  • To conserve system resources, avoid scanning email messages twice. Scan messages as they enter and leave your network or when clients send and retrieve them, rather than both.
  • Enable Treat Windows Executables in Email Attachments as Viruses if you are concerned about incoming ‘.exe’ files.

FortiGuard web filtering

The web is the most popular part of the Internet and, as a consequence, virtually every computer connected to the Internet is able to communicate using port 80, HTTP. Botnet communications take advantage of this open port and use it to communicate with infected computers. FortiGuard Web Filtering can help stop infections from malware sites and help prevent communication if an infection occurs. FortiGuard web filtering recommendations

  • Enable FortiGuard Web Filtering at the network edge. l Install the FortiClient application and use FortiGuard Web Filtering on any systems that bypass your FortiGate unit.
  • Block categories such as Pornography, Malware, Spyware, and Phishing. These categories are more likely to be dangerous.
  • In the Anti-Spam profile, enable Spam Detection and Filtering and then enable IP Address Check. Many IP addresses used in spam messages lead to malicious sites; checking them will protect your users and your network.

DNS filter

DNS-based web filtering

This feature is similar to the FortiGuard DNS web filtering available in FortiOS 5.2. You can configure DNS web filtering to allow, block, or monitor access to web content according to FortiGuard categories. When DNS web filtering is enabled, your FortiGate must use the FortiGuard DNS service for DNS lookups. DNS lookup requests Content inspection and filtering

sent to the FortiGuard DNS service return with an IP address and a domain rating that includes the FortiGuard category of the web page.

If that FortiGuard category is set to block, the result of the DNS lookup is not returned to the requester. If the category is set to redirect, then the address returned to the requester points at a FortiGuard redirect page.

You can also allow access or monitor access based on FortiGuard category.

The following filtering options can be configured in a DNS Filter security profile:

Blocking DNS requests to known Botnet C&C addresses

A new FortiGuard database contains a list of known Botnet C&C addresses. This database is updated dynamically and stored on the FortiGate. This database is covered by FortiGuard web filter licensing; you must have an active FortiGuard web filtering license to use this feature. You can view the botnet lists by going to System > FortiGuard > Botnet IPs and System > FortiGuard > Botnet Domains.

When you block DNS requests to known Botnet C&C addresses, using IPS, DNS lookups are checked against the Botnet C&C database. All matching DNS lookups are blocked. Matching uses a reverse prefix match, so all subdomains are also blocked.

To enable blocking of DNS requests to known Botnet C&C addresses, go to Security Profiles > DNS Filter, and enable Block DNS requests to known botnet C&C. When you do this in FortiOS 5.4.1, you can open a definitions window by clicking on “botnet package.”

Static URL filter

The DNS static URL filter allows you to block, exempt, or monitor DNS requests by using IPS to look inside DNS packets and match the domain being looked up with the domains on the static URL filter list. If there is a match the DNS request can be blocked, exempted, monitored, or allowed.

If blocked, the DNS request is blocked and so the user cannot look up the address and connect to the site.

If exempted, access to the site is allowed even if another method is used to block it.


Spam is a common means by which attacks are delivered. Users often open email attachments they should not, and infect their own machine. The FortiGate email filter can detect harmful spam and mark it, alerting the user to the potential danger.

Anti-Spam filter recommendations

l Subscribe to the FortiGuard Anti-Spam Filtering service. l Enable email filtering at the network edge for all types of email traffic. l Use FortiClient endpoint scanning for protection against threats that get into your network.

Data Leak Prevention

Most security features on the FortiGate unit are designed to keep unwanted traffic out of your network while Data Leak Prevention (DLP) can help you keep sensitive information from leaving your network. For example, credit card numbers and social security numbers can be detected by DLP sensors.

DLP recommendations

  • Rules related to HTTP posts can be created, but if the requirement is to block all HTTP posts, a better solution is to use application control or the HTTP POST Action option in the web filter profile.
  • While DLP can detect sensitive data, it is more efficient to block unnecessary communication channels than to use DLP to examine it. If you don’t use instant messaging or peer-to-peer communication in your organization, for example, use application control to block them entirely.

Security profile components

Below is a brief description of the security profiles and their features.


Your FortiGate unit stores a virus signature database that can identify more than 15,000 individual viruses.

FortiGate models that support additional virus databases are able to identify hundreds of thousands of viruses. With a FortiGuard AntiVirus subscription, the signature databases are updated whenever a new threat is discovered.

AntiVirus also includes file filtering. When you specify files by type or by file name, the FortiGate unit will block the matching files from reaching your users.

FortiGate units with a hard drive or configured to use a FortiAnalyzer unit can store infected and blocked files for that you can examine later.

Web filter

Web filtering includes a number of features you can use to protect or limit your users’ activity on the web.

FortiGuard Web Filtering is a subscription service that allows you to limit access to web sites. More than 60 million web sites and two billion web pages are rated by category. You can choose to allow or block each of the 77 categories.

URL filtering can block your network users from access to URLs that you specify.

Web content filtering can restrict access to web pages based on words and phrases appearing on the web page itself. You can build lists of words and phrases, each with a score. When a web content list is selected in a web filter profile, you can specify a threshold. If a user attempts to load a web page and the score of the words on the page exceeds the threshold, the web page is blocked.

DNS filter

The FortiGate will inspect DNS traffic to any DNS server, so long as the policy has DNS inspection enabled. The

FortiGate will intercept DNS requests, regardless of the destination IP, and redirect it to the FortiGuard Secure

Security profile components

DNS server — this is separate from the FortiGuard DNS server.

The Secure DNS server will resolve and rate the FQDN and send a DNS response which includes both IP and rating of the FQDN back to the FortiGate, where it will handle the DNS response according to the DNS filter profile.

Application control

Although you can block the use of some applications by blocking the ports they use for communications, many applications do not use standard ports to communicate. Application control can detect the network traffic of more than 1,000 applications, improving your control over application communication.

Cloud Access Security Inspection (CASI)

This feature introduces a new security profile called Cloud Access Security Inspection (CASI) that provides support for fine-grained control on popular cloud applications, such as YouTube, Dropbox, Baidu, and Amazon. The CASI profile is applied to a policy much like any other security profile.

Unfortunately CASI does not work when using Proxy-based profiles for AV or Web filtering for example.

Make sure to only use Flow-based profiles in combination with CASI on a specific policy.

Intrusion protection

The FortiGate Intrusion Protection System (IPS) protects your network against hacking and other attempts to exploit vulnerabilities of your systems. More than 3,000 signatures are able to detect exploits against various operating systems, host types, protocols, and applications. These exploits can be stopped before they reach your internal network.

You can also write custom signatures tailored to your network.


FortiGuard Anti-Spam is a subscription service that includes an IP address black list, a URL black list, and an email checksum database. These resources are updated whenever new spam messages are received, so you do not need to maintain any lists or databases to ensure accurate spam detection.

You can use your own IP address lists and email address lists to allow or deny addresses, based on your own needs and circumstances.

Data Leak Prevention

Data Leak Prevention (DLP) allows you to define the format of sensitive data. The FortiGate unit can then monitor network traffic and stop sensitive information from leaving your network. Rules for U.S. social security numbers, Canadian social insurance numbers, as well as Visa, Mastercard, and American Express card numbers are included.

profile components


The Session Initiation Protocol (SIP) is an IETF application layer signaling protocol used for establishing, conducting, and terminating multi-user multimedia sessions over TCP/IP networks using any media. SIP is often used for Voice over IP (VoIP) calls but can be used for establishing streaming communication between end points.

For more information, see VoIP Solutions: SIP.


This module allows for the offloading of certain processes to a separate server so that your FortiGate firewall can optimize its resources and maintain the best level of performance possible.

FortiClient profiles

FortiClient is an all-in-one comprehensive endpoint security solution that extends the power of Fortinet’s Advanced Threat Protection (ATP) to end user devices. As the endpoint is the ultimate destination for malware that is seeking credentials, network access, and sensitive information, ensuring that your endpoint security combines strong prevention with detection and mitigation is critical.

The FortiGate provides network security by defining compliance rules for FortiClient endpoints.

For more information, see the FortiClient 5.4.1 Administration Guide.

Proxy options

Proxy Options includes features you can configure for when your FortiGate is operating in proxy mode, including protocol port mapping, block oversized files/emails, and other web and email options.

SSL/SSH inspection

SSL/SSH Inspection (otherwise known as Deep Inspection) is used to scan HTTPS traffic in the same way that HTTP traffic can be scanned. This allows the FortiGate to receive and open up the encrypted traffic on behalf of the client, then the traffic is re-encrypted and sent on to its intended destination.

Individual Deep Inspection profiles can be created, depending on the requirements of the policy. Depending on the profile, you can:

l Configure which CA certificate will be used to decrypt the SSL encrypted traffic l Configure which SSL protocols will be inspected l Configure which ports will be associated with which SSL protocols for inspection l Configure whether or not to allow invalid SSL certificates l Configure whether or not SSH traffic will be inspected

Security profiles/lists/sensors

Security profiles/lists/sensors

A profile is a group of settings that you can apply to one or more firewall policies. Each Security Profile feature is enabled and configured in a profile, list, or sensor. These are then selected in a security policy and the settings apply to all traffic matching the policy. For example, if you create an antivirus profile that enables antivirus scanning of HTTP traffic, and select the antivirus profile in the security policy that allows your users to access the World Wide Web, all of their web browsing traffic will be scanned for viruses.

Because you can use profiles in more than one security policy, you can configure one profile for the traffic types handled by a set of firewall policies requiring identical protection levels and types, rather than repeatedly configuring those same profile settings for each individual security policy.

For example, while traffic between trusted and untrusted networks might need strict protection, traffic between trusted internal addresses might need moderate protection. To provide the different levels of protection, you might configure two separate sets of profiles: one for traffic between trusted networks, and one for traffic between trusted and untrusted networks.

This entry was posted in Administration Guides, FortiOS 6 on by .

About Mike

Michael Pruett, CISSP has a wide range of cyber-security and network engineering expertise. The plethora of vendors that resell hardware but have zero engineering knowledge resulting in the wrong hardware or configuration being deployed is a major pet peeve of Michael's. This site was started in an effort to spread information while providing the option of quality consulting services at a much lower price than Fortinet Professional Services. Owns PacketLlama.Com (Fortinet Hardware Sales) and Office Of The CISO, LLC (Cybersecurity consulting firm).

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