MANDIANT closes round of strategic investment with One Equity Partners, Kleiner Perkins Caufield & Byers

Alexandria, Va., June 27, 2011 — MANDIANT, the leader in advanced threat detection and
response solutions and services, today announced that One Equity Partners (OEP), the private
investment arm of JPMorgan Chase & Co., and Kleiner Perkins Caufield & Byers (KPCB) have
completed a strategic investment in the company. MANDIANT also announced the addition of
Ted Schlein (KPCB) and A. Jody Gessow (OEP) to its Board of Directors.

“We look forward to scaling and meeting the significant demand for MANDIANT products and
services with the resources of KPCB and OEP,” said MANDIANT CEO Kevin Mandia. “Ted and
Jody bring decades of proven security and executive experience and we welcome them to the
board.”

“Over recent months the importance of knowing whether your network has been breached has
become alarmingly clear. MANDIANT is the global leader in helping major corporate and
government entities answer this question and execute an effective response. With the
experience and financial resources of MANDIANT’s new investors, we are confident
MANDIANT will prosper in the years ahead. We are delighted to become their partner in fulfilling
their long-term goals,” said OEP’s Jody Gessow.

“The number and scope of advanced and targeted attacks continues to increase, and preventive
measures alone are no longer sufficient to protect organizations from intrusions”, said KPCB’s
Ted Schlein. “MANDIANT is uniquely positioned to be the early warning system for the next
wave of advanced attacks. I am excited to be part of the team that is doing so much to ensure
organizations have an aggressive and successful security posture.”

On May 16, the company launched MANDIANT Intelligent Response® (MIR) v2.0, featuring the
second generation of powerful host-based incident response for enterprise organizations.
Trusted by incident responders at the world’s largest banks, defense contractors, energy
companies and manufacturers, MIR 2.0 enables enterprises to respond faster, limit losses and
speed the return to normal business operations.