Analytics
9/12/2013
03:57 AM
Dark Reading
Dark Reading
Quick Hits
Connect Directly
RSS
E-Mail
50%
50%

Building And Maintaining Effective Firewall Configurations

The best firewalls in the world can still be misconfigured. Here are some tips for keeping yours up to snuff

[The following is excerpted from "Building and Maintaining Effective Firewall Configurations," a new report posted this week on Dark Reading's Perimeter Security Tech Center.]

Much of the innovation we're seeing in the perimeter security space today is happening in the areas of Web security and application intelligence, but advanced threats and intelligent malware aren't the only threat vectors you need to account for. Your entire perimeter security strategy must be built upon a strong foundation, and that starts with the execution of certain basic firewall configuration best practices. You can have the best intrusion-prevention system (IPS) and Web security tools on the planet, but if your firewall is misconfigured or mismanaged, then you are living in a house built on top of a sinkhole.

Proper configuration and management of your firewalls is a trivial exercise for the experienced firewall admin. But even the best among us can make the occasional mistake that can open up an attack vector. On the other end of the spectrum, less-seasoned firewall admins can open up gaping holes in their defenses without even knowing it.

Operational and management issues that create real security holes are only magnified when large teams of security pros are co-managing a large number of firewalls. If you're fortunate enough to be an experienced firewall admin wholly responsible for your farm of corporate firewalls, then consider yourself extremely lucky. But in most cases, the responsibility of managing a large number of firewalls spread across many sites is shared among a team of security pros. And as with any co-managed system, the more cooks in the kitchen, the greater the likelihood of errors, mistakes or misconfigurations in the broth.

All too often, we concentrate our time and effort on making sure our advanced security tools are doing an effective job. And all too often, we fail to pay attention to a crack in the foundation that can surface as a result of security policy misconfiguration. Here are some of the gotchas, tools and best practices that should be considered to ensure that your firewalls provide a strong foundation for the rest of your perimeter security strategy.

Rule-Based Configuration
Building and maintaining an effective firewall configuration starts with your rule base. Whether you're unpacking a firewall for the first time or pushing a new security policy to an existing firewall for the 1,000th time, the way in which you configure your firewall rules can help make you extremely secure or extremely insecure. It's easy for anyone to grasp the concept of what a firewall needs to do from a rule perspective, but implementation is key to avoiding gaping holes in your defenses. Even veteran firewall pros can make mistakes here, especially when trying to manage unfamiliar firewall platforms.

There are several basic best practices that should be used in the day-to-day management of your firewalls from a rule-based configuration perspective.

Don't lose track of your "deny-any" rule.
When you unpack a new firewall and start building a security policy from scratch, it's easy to visualize what hosts you're exposing to the Internet. However, that visualization gets infinitely more difficult when you have 300 rules in play.

Most enterprise-grade firewalls come with a "deny-any" rule base out of the box, and it's important not to lose track of it. The deny-any rule is commonly referred to as the "catch-all" rule because it ensures that any traffic not specifically allowed is dropped. Firewall admins can run into trouble when they set this action to "allow" and fail to set it back, or when they fail to see that the default action is set to allow. Even more likely: They configure an allow-any rule prior to reaching the catch-all rule, which defeats the whole purpose of the catch-all rule.

Beyond that, it's important not to be overly generous with the TCP/UDP services that you allow internal hosts access to on the Internet. If you are, then you're exposing your hosts to unnecessary risk of attack and/or malware infection.

To read more rules and tips for maintaining strong firewall configuration -- and for some easy-to-use controls you can add to your security policy -- download the free report.

Have a comment on this story? Please click "Add a Comment" below. If you'd like to contact Dark Reading's editors directly, send us a message.

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
Partner Perspectives
What's This?
In a digital world inundated with advanced security threats, Intel Security seeks to transform how we live and work to keep our information secure. Through hardware and software development, Intel Security delivers robust solutions that integrate security into every layer of every digital device. In combining the security expertise of McAfee with the innovation, performance, and trust of Intel, this vision becomes a reality.

As we rely on technology to enhance our everyday and business life, we must too consider the security of the intellectual property and confidential data that is housed on these devices. As we increase the number of devices we use, we increase the number of gateways and opportunity for security threats. Intel Security takes the “security connected” approach to ensure that every device is secure, and that all security solutions are seamlessly integrated.
Featured Writers
White Papers
Cartoon
Current Issue
Dark Reading's October Tech Digest
Fast data analysis can stymie attacks and strengthen enterprise security. Does your team have the data smarts?
Flash Poll
Threat Intel Today
Threat Intel Today
The 397 respondents to our new survey buy into using intel to stay ahead of attackers: 85% say threat intelligence plays some role in their IT security strategies, and many of them subscribe to two or more third-party feeds; 10% leverage five or more.
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-4594
Published: 2014-10-25
The Payment for Webform module 7.x-1.x before 7.x-1.5 for Drupal does not restrict access by anonymous users, which allows remote anonymous users to use the payment of other anonymous users when submitting a form that requires payment.

CVE-2014-0476
Published: 2014-10-25
The slapper function in chkrootkit before 0.50 does not properly quote file paths, which allows local users to execute arbitrary code via a Trojan horse executable. NOTE: this is only a vulnerability when /tmp is not mounted with the noexec option.

CVE-2014-1927
Published: 2014-10-25
The shell_quote function in python-gnupg 0.3.5 does not properly quote strings, which allows context-dependent attackers to execute arbitrary code via shell metacharacters in unspecified vectors, as demonstrated using "$(" command-substitution sequences, a different vulnerability than CVE-2014-1928....

CVE-2014-1928
Published: 2014-10-25
The shell_quote function in python-gnupg 0.3.5 does not properly escape characters, which allows context-dependent attackers to execute arbitrary code via shell metacharacters in unspecified vectors, as demonstrated using "\" (backslash) characters to form multi-command sequences, a different vulner...

CVE-2014-1929
Published: 2014-10-25
python-gnupg 0.3.5 and 0.3.6 allows context-dependent attackers to have an unspecified impact via vectors related to "option injection through positional arguments." NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-7323.

Best of the Web
Dark Reading Radio
Archived Dark Reading Radio
Follow Dark Reading editors into the field as they talk with noted experts from the security world.