Exhibit 99.1

SOURCEFIRE ANNOUNCES THIRD QUARTER 2012 RESULTS

Third Quarter 2012:

COLUMBIA, Md., November 1, 2012 – Sourcefire, Inc. (Nasdaq:FIRE), a leader in intelligent cybersecurity solutions, today announced financial results for its fiscal third quarter ended September 30, 2012.

“Sourcefire achieved record revenue for the third quarter. We saw broad based strength across our business driven by our market-leading FirePOWER platform and our growing distribution capabilities,” said Marty Roesch, interim CEO of Sourcefire. “Today’s sophisticated threats require an approach that provides continuous capability across all phases of an attack; before it begins, during the time it is in progress and even after it is missed by other defenses. Our threat centric approach addresses the full attack continuum and drives our innovation, resulting in more effective protection for our customers. This, combined with the investments we are making in our go-to-market strategy, is enabling us to achieve significant levels of growth.”

Financial Summary

Recent Company Highlights

Revenue Growth

Innovation & Recognition

Fourth Quarter and Full Year 2012 Outlook

Based on information as of October 30, 2012, Sourcefire expects revenue for the fourth quarter of 2012 in the range of $62.0 million to $64.0 million, net income per diluted share in the range of $0.03 to $0.05 and, on an adjusted basis, net income per diluted share in the range of $0.27 to $0.29. Sourcefire’s expectation of adjusted net income per diluted share excludes stock-based compensation expense of $10.0 million to $10.2 million (inclusive of $3.7 million of expense due to vesting acceleration of restricted shares in connection with the retirement of the Company’s former CEO) and amortization of acquired intangible assets of approximately $0.3 million, and includes an assumed 35% tax rate.

For fiscal year 2012 Sourcefire expects revenue in the range of $217.7 million to $219.7 million, net income per diluted share in the range of $0.11 to $0.13 and adjusted net income per diluted share in the range of $0.80 to $0.82. Sourcefire’s expectation of full year 2012 adjusted net income per share excludes stock-based compensation expense in the expected range of $26.1 million to $26.3 million and amortization of acquired intangible assets and other acquisition-related expenses of approximately $2.8 million and includes an assumed tax rate of 35%.

Non-GAAP Measures

To supplement its consolidated financial statements presented in accordance with GAAP, Sourcefire considers certain financial measures that are not prepared in accordance with GAAP, including non-GAAP adjusted net income, adjusted net income per share, adjusted income from operations, adjusted income from operations as a percentage of revenue and free cash flow.

Sourcefire uses these non-GAAP financial measures, in addition to GAAP financial measures, to evaluate its operating and financial performance and to compare such performance to that of prior periods and to the performance of its competitors. The Company also uses these non-GAAP financial measures in making operational and financial decisions and in establishing operational goals. Sourcefire believes that providing these non-GAAP financial measures to investors, as a supplement to GAAP financial measures, helps investors to evaluate the Company’s operating and financial performance and trends in its business, consistent with how management evaluates such performance and trends. The Company also believes these non-GAAP financial measures may be useful to investors in comparing its performance to the performance of other companies, although Sourcefire’s non-GAAP financial measures are specific to it and the non-GAAP financial measures of other companies may not be calculated in the same manner.

Adjusted Net Income, Adjusted Net Income per Share, Adjusted Income from Operations and Adjusted Income from Operations as a Percentage of Revenue: In evaluating the operating performance of its business, Sourcefire excludes certain charges and credits that are required by GAAP. These non-GAAP measures exclude (i) stock-based compensation, which does not involve the expenditure of cash, (ii) amortization of acquisition-related intangible assets, which does not involve the expenditure of cash, and (iii) other acquisition–related expenses, which are unrelated to the ongoing operation of the Company’s business in the ordinary course. For 2012 Sourcefire expects non-GAAP results to be adjusted to reflect the effect of an assumed tax rate of 35%. This adjustment is intended to normalize the tax rate and provide a tax rate that approximates the Company’s expected long-term GAAP tax rate.

Free Cash Flow: Sourcefire defines free cash flow as net cash provided by operating activities minus capital expenditures. The Company considers free cash flow to be a liquidity measure that provides useful information to management and investors about the amount of cash generated by the business that, after the purchase of property and equipment, can be used for strategic opportunities, including investing in the business, making strategic acquisitions and strengthening the balance sheet.

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. 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.

Conference Call and Webcast

On Thursday, November 1, 2012 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: 877-712-7037

Calling from other countries: 253-237-1122

Conference ID number: 39707384

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), a world leader in intelligent cybersecurity solutions, is transforming the way global large- to mid-size organizations and government agencies manage and minimize network security risks. With solutions from a next-generation network security platform to advanced malware protection, Sourcefire provides customers with Agile Security^® that is as dynamic as the real world it protects and the attackers against which it defends. Trusted for more than 10 years, Sourcefire has been consistently recognized for its innovation and industry leadership with numerous patents, world-class research, and award-winning technology. Today, the name Sourcefire has grown synonymous with innovation, security intelligence and agile end-to-end security protection. For more information about Sourcefire, please visit www.sourcefire.com.

Sourcefire, the Sourcefire logo, Snort, the Snort and Pig logo, ClamAV, FireAMP, FirePOWER, FireSIGHT and certain other trademarks and logos are trademarks or registered trademarks of Sourcefire, Inc. in the United States and other countries. Other company, product and service names may be trademarks or service marks of others.

Cautionary Language Concerning Forward-Looking Statements

The statements contained in this release that are not historical facts are “forward-looking statements” (as such term is defined in the Private Securities Litigation Reform Act of 1995) that involve risks and uncertainties. These statements include expectations regarding financial results for the fourth quarter of 2012 and expectations of future growth.

Management cautions the reader that these forward-looking statements are only predictions and are subject to a number of both known and unknown risks and uncertainties, and actual results, performance, and/or achievements of Sourcefire, Inc. may differ materially from the future results, performance, and/or achievements expressed or implied by these forward-looking statements as a result of a number of factors. These factors include, without limitation, the fact that the outlook for the fourth quarter of 2012 and expectations of future growth could change, the risk that the search for a new CEO or the transition to a new CEO could disrupt the Company’s business and also include, without limitation, those risks and uncertainties described from time to time in the reports filed by Sourcefire, Inc. with the U.S. Securities and Exchange Commission. Sourcefire, Inc. undertakes no obligation to update any forward-looking statements.

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Sourcefire, Inc.

Consolidated Statements of Operations

(in thousands, except share and per share data)

Stock-based compensation expense for the three and nine months ended September 30, 2012 and 2011 is included in the Consolidated Statements of Operations as follows (in thousands):

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Condensed Consolidated Balance Sheets

(in thousands)

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Condensed Consolidated Statements of Cash Flows

(in thousands)

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Reconciliation of Non-GAAP Measures to GAAP

(in thousands, except share and per share data)

Reconciliation of net cash provided by (used in) operating activities to free cash flow:

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Supplemental Operating Data