ArcSight Appoints Dr. Prescott Winter, Former CIO and CTO of the NSA, as CTO for Public Sector

National Security and Intelligence Veteran Brings Nearly Three Decades of Experience at NSA and Office of Director of National Intelligence to ArcSight

CUPERTINO, CA – March 3, 2010 – ArcSight, Inc. (NASDAQ: ARST), a leading global provider of security and compliance management solutions that protect enterprises and government agencies, today announced the appointment of Dr. Prescott Winter as CTO, Public Sector. Dr. Winter previously served as CIO and CTO of the National Security Agency (NSA) and brings almost three decades of combined experience in the public sector to the role. In this new role at ArcSight, Dr. Winter will drive strategic product initiatives and industry relationships concerning public sector cyber-security requirements in the US and internationally, as well as facilitate collaboration between the public and private sector on the ever changing global cyber-threat landscape.

In addition to his senior roles at NSA, Dr. Winter was most recently the Associate Deputy Director of National Intelligence for Information Integration, where he established a national scale program to integrate and share information across the intelligence community. Prior to his work at the Office of the Director of National Intelligence (ODNI), Dr. Winter served more than 25 years at the NSA. He began his career at NSA in 1982, holding senior positions such as Deputy Chief, Defensive Information Operations; Chief, Customer Response; Chief, NSA Commercial Solution Center, as well as CIO and CTO. During his tenure, Dr. Winter created the agency’s first integrated technology service provider organization and its first multi-mission industrial relations office to develop and nurture strong partnerships with industry. He was also responsible for NSA communications and reporting policy to customers.

“It’s a great honor to bring someone with Prescott’s background to our team,” said Hugh Njemanze, Chief Technology Officer and Executive Vice President of Research and Development of ArcSight. “He is known across the industry for his extensive experience integrating policy, culture and training with technology issues and managing teams with a strong dedication to customer needs."

About ArcSight

ArcSight (NASDAQ: ARST) is a leading global provider of security and compliance management solutions that protect businesses and government agencies. ArcSight identifies, assesses, and mitigates both internal and external cyber threats and risks across the organization for activities associated with critical assets and processes. With the market-leading ArcSight SIEM platform, organizations can proactively safeguard their assets, comply with corporate and regulatory policy and control the risks associated with cyber-theft, cyber-fraud, cyber-warfare and cyber-espionage. For more information, visit www.arcsight.com. (ARST-IR)

Cautionary Statement Regarding Forward Looking Statements
This news release contains forward-looking statements, including without limitation those regarding Dr. Winter’s role in driving strategic product initiatives and industry relationships and in facilitating collaboration between the public and private sector. These forward-looking statements are subject to material risks and uncertainties that may cause actual results to differ substantially from expectations. Investors should consider important risk factors, which include: the risk that Dr. Winter may be unable to make the contributions that are anticipated; and other risks detailed under the caption “Risk Factors” in the ArcSight Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission, or the SEC, on December 9, 2009 and the company’s other filings with the SEC. You can obtain copies of the company’s Quarterly Report on Form 10-Q and its other SEC filings on the SEC’s website at www.sec.gov.

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Media Contact:
Atomic PR for ArcSight
Chris Fucanan
415-593-1400
chris.fucanan@atomicpr.com