Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Analytics

5/29/2009
02:48 PM
50%
50%

Tech Insight: To Go Deep On Security, Get Past The Surface

Reducing the "attack surface" of your Microsoft apps and systems could improve your organization's overall security

A Special Analysis for Dark Reading

Each new version of a software product, such as Microsoft Word, brings new features -- whether users want them or not. What many users and sysadmins don't recognize is that each additional feature brings more code, and each new bit of code expands the area of potential vulnerability -- the "attack surface" -- for the application.

Security professionals have been working for years to reduce the attack surface of their applications, principally by disabling unnecessary functionality in an effort to strike a balance between security and usability.

But what exactly is the attack surface of an application, network, or computer system, and how do you measure it? Wikipedia defines it well: "The attack surface of a software environment is the scope of functionality that is available to any application user, particularly unauthenticated users. This includes, but is not limited to, user input fields, protocols, interfaces, and services." Of course, this definition can be easily expanded to include more than just software environments.

Measuring an attack surface is not difficult, provided that you start with a clear understanding of the attack points of the target you're evaluating. The Wikipedia definition includes a short list of attack points, but for a more comprehensive list, Michael Howard wrote an article for the Microsoft Developer Network in 2003 that offers a list used to measure the attack surface of the Windows operating system. He simplified the definition of measuring attack surface to "determining the attackability of a system or its exposure to attack."

Minimizing the attack surface is the next logical step, and is common practice for sysadmins and security professionals through the use of best practices for system hardening and building secure networks. The goal -- and not one that has been easily obtainable in the past with Windows -- is to minimize the entry points for unauthenticated, anonymous users, and to mitigate the amount of damage that could be caused if they gained access.

The standard recommendations for attack surface reduction in Windows systems is to turn off any unnecessary services, disable or delete unnecessary accounts, limit users to the least amount of privilege necessary to do their jobs, enable the firewall, use antivirus, and so on. We've heard this advice for years, but what about choosing an operating system that helps reduce the attack surface by offering a minimal install and unnecessary services enabled by default?

Microsoft has been trying to reduce the attack surface of a default Windows installation since the release of Windows Server 2003 Web Edition. While that probably wasn't the original intent of the Web Edition, it was limited to acting primarily as a Web server and nothing else -- which effectively minimized its attack surface. Only minimal installs of MS SQL Server (MSDE and Express) could be installed, while Exchange could not be installed at all. Even .NET was not included in the default install.

In terms of a minimized attack surface, the real head-turner is the Server Core installation option in Windows Server 2008. Microsoft has created a choice for sysadmins to deploy a minimal system that does not include the typical Windows Explorer and GUI. Instead, when you log in, you are presented with two command prompt windows. There is no Start menu or taskbar. Management is accomplished through command line tools or by connecting from another system via the Microsoft Management Console (MMC).

Security isn't the only benefit of reducing a system's attack surface. Server Core, for example, requires fewer hardware resources because of its reduced footprint, which means sysadmins who are considering Hyper-V for virtualization now can devote hardware resources to virtual machines instead of the underlying server operating system.

The trend is apparent in Windows Server operating systems, the reliance on virtualization, and the realization that reducing the attack surface is critical. That's why the trend should continue among future versions of Windows Server. It's a win-win for sysadmins and security pros, who have less to lock down and disable, making deployment faster and auditing easier.

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

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
News
Inside the Ransomware Campaigns Targeting Exchange Servers
Kelly Sheridan, Staff Editor, Dark Reading,  4/2/2021
Commentary
Beyond MITRE ATT&CK: The Case for a New Cyber Kill Chain
Rik Turner, Principal Analyst, Infrastructure Solutions, Omdia,  3/30/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2021-20491
PUBLISHED: 2021-04-16
IBM Spectrum Protect Server 7.1 and 8.1 is subject to a stack-based buffer overflow caused by improper bounds checking during the parsing of commands. By issuing such a command with an improper parameter, an authorized administrator could overflow a buffer and cause the server to crash. IBM X-Force ...
CVE-2021-22539
PUBLISHED: 2021-04-16
An attacker can place a crafted JSON config file into the project folder pointing to a custom executable. VScode-bazel allows the workspace path to lint *.bzl files to be set via this config file. As such the attacker is able to execute any executable on the system through vscode-bazel. We recommend...
CVE-2021-31414
PUBLISHED: 2021-04-16
The unofficial vscode-rpm-spec extension before 0.3.2 for Visual Studio Code allows remote code execution via a crafted workspace configuration.
CVE-2021-26073
PUBLISHED: 2021-04-16
Broken Authentication in Atlassian Connect Express (ACE) from version 3.0.2 before version 6.6.0: Atlassian Connect Express is a Node.js package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Express app occurs with a server-to-server JWT or ...
CVE-2021-26074
PUBLISHED: 2021-04-16
Broken Authentication in Atlassian Connect Spring Boot (ACSB) from version 1.1.0 before version 2.1.3: Atlassian Connect Spring Boot is a Java Spring Boot package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Spring Boot app occurs with a se...