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:

• HTTPS l SMTPS l POP3S l IMAPS l FTPS

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.

AntiVirus

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.

Anti-Spam

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.

AntiVirus

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.

Anti-spam

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

VoIP

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.

ICAP

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.

Inside FortiOS: Web Filtering

A Web Filtering solution is designed to restrict or control the content a reader is authorized to access, delivered over the Internet via the Web browser. It may be used to improve security, prevent objectionable activities, and increase productive within an organization.

Intelligent and effective content control

Web-based threats such as Phishing, drive-by Malware sites, and Botnets are more sophisticated and scrutinized than ever, and as well as increasingly difficult to control due to the rise of mobility in the workplace, even more difficult for you to control. The Web has become the preferred medium of choice for hackers and thieves looking for new ways to disrupt services, steal information, and perform malicious activities for financial gain. In addition, employees who visit websites containing objectionable content can expose your organization to civil or criminal liability.

FortiOS Web Filtering solution utilizes three main components of the web filtering function: the Web Content Filter, the URL Filter, and the FortiGuard Web Filtering Service. These functions integrate with each other to provide maximum control over what the Internet user can view as well as protection to the network from many Internet content threats. Web Content Filtering blocks web pages containing words or patterns that you specify. URL filtering uses URLs and URL patterns to block or exempt web pages from specific sources. FortiGuard Web Filtering provides many additional categories you can use to filter web traffic by independent real-world tests.

Highlights

• Comprehensive and advanced Web Filtering features Safe Search and user override options. l FortiGuard Web Filtering Services with superior coverage of over 250 million rated websites. l Integration with other FortiOS components, such as User Identification for flexible and secured implementation. l Supports detection for traffic using HTTP protocol (versions 1.0, 1.1, and 2.0).
• Ability to configure web filtering by adding URL categories to security policies when operating in flow-based inspection and NGFW policy-based mode. You can set the action to accept or deny to allow or block the applications.

Key features & benefits

Features

Cloud-based rating system

Fortinet is a pioneer in cloud-based rating systems for web filtering. FortiOS provides an innovative approach to HTTP and HTTPS web filtering technology by combining the advantages of a cloud-based service offering with layered response caching. The multiple FortiGuard data centers around the world hold the entire categorized URL database and receive rating requests from FortiGate units triggered by browser-based URL requests.

FortiGuard responds to these rating requests with the categories stored for specific URLs, the requesting FortiGate unit then uses its own local profile configuration to determine what action is appropriate to the category, such as: blocking, monitoring, allowing the page, displaying a warning, or requiring authentication to view the page.

Rating responses are also cached directly in FortiGate unit memory so that ratings for frequently used sites can be retrieved directly from the cache, reducing the number of requests to the FortiGuard network. Caching URLs in memory makes URL lookups almost instantaneous while only using a very small amount of system memory.

An appropriately licensed FortiManager appliance can be synchronized to the FortiGuard network and as such can be used in the same way to as the FortiGuard network for managed FortiGate devices. This can further reduce any latency associated with the round trip time for individual rating requests while at the same time ensuring complete database coverage. Consider the combination of a LAN attached FortiGate cluster and FortiManager combination with the potential to handle tens of thousands of requests per second.

Superior coverage

FortiGuard Web Filter ratings are performed by a combination of proprietary methods including text analysis, exploitation of the web structure, and human raters. This service currently rates more than 250 million sites covering billions of URLs with each site able to be rated in multiple categories. The FortiGuard database provides a truly international service with support for 70 languages.

Extensive and flexible categorization

Rated URLs are assigned into one of the 98 categories (including 20 user defined ones) which administrators can then easily manage and control. Administrators can configure and populate local categories or place specific URLs in existing categories should the FortiGuard rating not be in agreement with an organization’s policies and practices.

Rating override

At times, administrators may have to allow approved people to access what they need during periods when an exception to the normal rules is required, while still having enough control that the organization’s web usage policies are not compromised. FortiOS can provide such setup by using alternate profiles.

Protection against malicious URLs

The malicious URL database contains all malicious URLs active in the last month and is organized as one of the categories. With Fortinet Security Fabric, customers can further their protection by having the FortiSandbox add newly discovered URLs to a dynamic URL filter, thus blocking files from being downloaded again from that URL.

Inspection modes

FortiOS web filtering can operate in different modes: proxy-based and flow-based inspection modes and DNS filtering. Each mode has strengths and weaknesses and all three can be active at the same time on different traffic streams.

Proxy-based web filtering uses a proxy to assemble and analyze web content as it passes through the FortiGate unit. If a page is blocked the proxy can replace the blocked page with a customizable web page informing users that the page is blocked. Proxy-based web filtering is the most feature-rich mode, supporting many advanced filters including web content filtering that analyzes web page content according to your custom requirements, Java applet filtering, and blocking invalid URLs.

Flow-based web filtering uses the FortiOS IPS engine to filter web content packets as they pass through the FortiGate unit without any buffering. Flow-based inspection does not use a proxy, so inspected packets are not proxied and altered by the FortiGate unit. Flow-based inspection does not support as many advanced features as proxy-based web filtering.

To control your FortiGate’s security profile inspection mode in FortiOS 5.6, you can select Flow or Proxy Inspection Mode from System > Settings. Having control over flow and proxy mode is helpful if you want to ensure that only flow inspection mode is used.

In most cases proxy mode is preferred because more security profile features are available and more configuration options for these individual features are available. Some implementations, however, may require all security profile scanning to only use flow mode. In this case, you can set your FortiGate to flow mode knowing that proxy mode inspection will not be used. Two new policy modes are available in FortiOS 5.6.

l NGFW mode simplifies applying application control and web filtering to traffic by allowing you to add applications and web filtering profiles directly to policies. This is used in conjunction with flow-based inspection. l Transparent proxy allows you to apply web authentication to HTTP traffic without using the explicit proxy.

DNS web filtering employs DNS lookups to the FortiGuard DNS service to get web page ratings. Filtering is done as part of the DNS lookup and web pages can be blocked or redirected to a web filter block page before the HTTP session starts. As a result, it is lightweight in terms of resource usage although it only supports a limited number of advanced features.

Usage quota

Administrators can set a daily timed access quota by category or category group. Quotas allow access for a specified length of time or traffic volume, calculated separately for each user.

SafeSearch

SafeSearch is a feature of popular search sites that prevents explicit web sites and images from appearing in search results. Although SafeSearch is a useful tool, especially in educational environments, the resourceful user may be able to simply turn it off. Enabling SafeSearch on the FortiGate for the supported search sites can better enforce its use by rewriting the search URL to include the code to indicate the use of the SafeSearch feature.

Restrict YouTube access

In FortiOS 5.6 with inspection mode set to proxy-based, you can set Strict or Moderate access to YouTube in a Web Filter profile.

Manual URL and content filter

FortiOS web filtering offers specific URL filtering by standard, wildcard, and regular expression definition, as well as content filtering by pattern type and language.

Advanced web filter configurations

FortiOS rich feature set includes ability to implement a number of enterprise features such as:

• Block HTTP redirects by rating, invalid URLs, HTTP POST actions, and Web resume download l Cookie, Java applet, and ActiveX filter
• Rate Images by URL and URLs by domain and IP address

Proxy avoidance preventions

FortiGate is able to improve the effectiveness of the web filtering by preventing users from evading the security implementation. Organizations can use its multiple integrated technologies including proxy site URL, proxy application control, and IPS proxy behavior blocking.

User and device awareness

Most networks in today’s organizations are connected with both corporate and personal mobile devices. User and device awareness provides the option to configure intelligent policies that can effectively enforce security.

To tackle the prevalence of BYOD environments, administrators are able to configure web content access policies with sources defined by IPs, users, and devices, either combined or selectively.

External URL filtering support

In instances where customers have large, existing, deployed implementations of a specific URL filtering solution but replace their legacy firewalls with a FortiGate family, they can still retain their web filtering infrastructure since FortiOS supports both ICAP and WISP.

Monitoring, logging, and reporting

FortiOS empowers an organization to implement security best practices that require continuous monitoring of threats, allowing the organization to adapt to new requirements.

The FortiView dashboards display useful analysis data with detailed and contextual session information, which can be filtered and ranked, with drilldown options also available. This information, including system events activities and administration audit trails, can also be archived via logs.

FortiOS logs all the types of traffic that can connect to or terminate at the FortiGate unit. In turn, these logs can generate useful trending and overview reports.