PRESS RELEASE

* Revenue: $25.8 million, an increase of 39% year-over-year * GAAP Net Income: $0.8 million, or $0.03 per diluted share * Adjusted Net Income: $2.0 million, or $0.07 per diluted share

Columbia, Md., April 29, 2010 " Sourcefire, Inc. (Nasdaq: FIRE), the creators of SNORT' and a leader in intelligent cybersecurity solutions, today announced financial results for its fiscal first quarter ended March 31, 2010.

"Building on the success we had in 2009, we had a strong start in our first quarter," said John Burris, CEO of Sourcefire. "I'm very pleased that we posted our fourth consecutive quarter of positive earnings and a profitable first quarter for the first time in the Company's history."

Financial Summary

* Total Revenues - Revenues for 1Q10 were $25.8 million compared to $18.6 million in 1Q09, an increase of 39%.

* GAAP Net Income - Net income was $0.8 million for 1Q10, or $0.03 per diluted share, on the basis of generally accepted accounting principles (GAAP), compared with GAAP net loss of $1.1 million, or a loss of $0.04 per diluted share, in 1Q09.

* Adjusted Net Income - Adjusted net income for 1Q10, which excludes stock-based compensation expense and assumes a tax rate of 35%, was $2.0 million, or $0.07 per diluted share. This compares to adjusted net income in 1Q09, which excludes stock-based compensation expense and assumes a tax rate of 35%, of $0.1 million, or $0.00 per diluted share.

* Balance Sheet - As of March 31, 2010, the Company's cash, cash equivalents and investments totaled $134.2 million.

First Quarter Company Highlights

International Expansion & Indirect Channel Development

* Increased U.S. commercial revenues to $12.2 million, up 28% over 1Q09. * Increased U.S. federal sector revenues to $6.1 million, up 132% over 1Q09. * Increased international revenues to $7.5 million, up 17% over 1Q09. * Achieved channel influenced deals of 30% of total 1Q10 deals, compared with 17% in 1Q09. * Launched the Global Security Alliance Channel Program, a new multi-tiered marketing and training program for resellers and distributors. Sourcefire created the program to strengthen channel reseller relationships and support them through higher margin sales training and marketing activities. Sourcefire has closely aligned its field sales team and marketing programs with channel partners and added increased training and incentives to position itself as the channel's "Trusted Go To Security Provider." * Added new Regional Sales Director of Central and Eastern Europe overseeing sales in Germany, Austria, Switzerland and across the Eastern European countries.

Innovation & Recognition

* Recognized by Everything Channel's CRN magazine for work of two of the Company's executives. Company founder and CTO, Martin Roesch, named a Security Superstar and Chris Peterson, Vice President of Worldwide Channel Sales, named a 2010 Channel Chief. Sourcefire is dedicating significant resources to the channel, providing products and programs to help our partners build customer loyalty. * Led the industry in same-day patch coverage with the Sourcefire VRT. The Sourcefire VRT is dedicated to protecting Sourcefire customers and Snort users by verifiably defending against attacks on vulnerabilities before specific exploits proliferate in the wild, while minimizing false positives and eliminating false negatives. * Partnered with Immunet to deliver cloud-based antivirus protection. The companies are delivering a free, Windows-based version of the ClamAV antivirus solution. The new ClamAV for Windows leverages Immunet's Cloud-based Collective Immunity technology, linking together a user's network of friends to identify new threats in real-time, providing instant protection across the product's user-base. * Named a finalist in two categories for SC Magazine Awards 2010 Europe. The company has been selected as a finalist in the Best Network Security group and the New! Best Secure Virtualization Solution category. * Expanded the Sourcefire 3D System to support the Xen 3.3.2 and 3.4.2 virtualization platforms. Now supporting the two leading virtual environments " Xen and VMware " Sourcefire is enabling customers with diverse virtual platforms to further protect these investments, while also leveraging these resources to increase intrusion prevention capabilities.

Second Quarter 2010 Outlook Based on information as of April 29, 2010, Sourcefire expects revenue for the second quarter of 2010 in the range of $27.2 million to $28.7 million, net income per diluted share in the range of $0.02 to $0.05 and, on an adjusted basis, net income per diluted share in the range of $0.06 to $0.09. Sourcefire's expectation of adjusted net income per diluted share excludes stock-based compensation expense for the second quarter in the expected range of $2.0 million to $2.2 million and includes an adjustment to reflect the effect of an assumed tax rate of 35%.

Non-GAAP Measures

In addition to reporting financial results in accordance with U.S. generally accepted accounting principles, or GAAP, in evaluating the operating performance of its business, Sourcefire's management excludes certain charges and credits that are required by GAAP. These non-GAAP results provide useful information to both management and investors by excluding (i) stock-based compensation, which does not involve the expenditure of cash, and (ii) items that Sourcefire believes may not be indicative of the Company's operating performance, because either they are unusual and Sourcefire does not expect them to recur in the ordinary course of its business or they are unrelated to the ongoing operation of the business in the ordinary course.

The non-GAAP results have also been adjusted to reflect the effect of an assumed tax rate of 35%, which differs from the Company's GAAP tax rate as a result of the utilization of net operating losses carried forward from prior periods to offset a portion of its current tax liability. Sourcefire believes this adjustment provides useful information to both management and investors because it more accurately reflects the Company's expected long-term tax rate.

The specific non-GAAP measures reported by Sourcefire are adjusted net income, adjusted net income per share and adjusted income from operations. The non-GAAP measures included in this press release have been reconciled to the nearest GAAP measure in the table following the financial statements attached to this press release. These measures should be considered in addition to results prepared in accordance with GAAP, but should not be considered a substitute for, or superior to, GAAP results.

Conference Call and Webcast

On Thursday, April 29, 2010 at 8:30 a.m. Eastern Time, Sourcefire will host a conference call to review these results. A listen-only web cast of the session will be available at http://investor.sourcefire.com. Those wishing to participate in the live session should use the following numbers to dial in:

Calling from the United States or Canada: 866-356-3095

Calling from other countries: 617-597-5391

Pass code: 58594200

An online replay will be available at http://investor.sourcefire.com following the completion of the live call and will remain available for at least 90 days.

About Sourcefire Sourcefire, Inc. (Nasdaq:FIRE) is a world leader in intelligent Cybersecurity solutions. Sourcefire is transforming the way Global 2000 organizations and government agencies manage and minimize network security risks. Sourcefire's IPS and Real-time Adaptive Security solution equips customers with an efficient and effective layered security defense " protecting network assets before, during and after an attack. Through the years, Sourcefire has been consistently recognized for its innovation and industry leadership by customers, media and industry analysts alike " with more than 50 awards and accolades. Today, the names Sourcefire and founder Martin Roesch have grown synonymous with innovation and network security intelligence. For more information about Sourcefire, please visit http://www.sourcefire.com.