Tom Brennan is the Chief Information Officer at Mandelbaum Barrett PC. A U.S. Marine veteran and long‑recognized cybersecurity expert, he brings decades of experience in penetration testing, vulnerability assessment, and application security to his leadership role in the legal sector.
Brennan previously served in senior roles with CREST International, including oversight of U.S. Government and partnership initiatives, and formerly held positions on both the global board of directors of the OWASP Foundation and as president of its New York City chapter.
He is a founding member of Nonprofit Cyber (www.nonprofitcyber.org), a coalition dedicated to strengthening cybersecurity across the nonprofit sector worldwide.
Brennan contributes significant time and expertise to universities such as High Point University, the University of New Haven, Saint John’s University, the NYU Tandon School of Engineering, and the New Jersey Institute of Technology (NJIT), supporting academic advancement in cybersecurity and advising on workforce development, curriculum, and emerging industry trends.
In addition to his corporate and academic work, he donates his time to The Retired Investigators Guild (www.therig.org), an organization focused on solving cold case murders by leveraging experienced investigators and modern forensic resources.
He is the founder of Proactive Risk, a boutique consultancy specializing in third‑party risk management and tailored cybersecurity solutions that help organizations better understand, measure, and manage their vendor‑related exposures.
Outside of his professional and volunteer commitments, Brennan enjoys 4×4 adventures and spending time outdoors, reflecting his lifelong appreciation for hands‑on challenges and exploration
Join Tom Brennan at the 7th Annual SecureWorld in New York City: “Strengthening Cybersecurity with CIS Controls v8”
October 28, 2025
We’re Heading to SecureWorld New York City! Tom Brennan, CIO at the firm, will be presenting “Strengthening Cybersecurity with CIS Controls v8” on October 29, 8:00–8:45 AM at the New York Marriott Marquis. His session will give a clear overview of the CIS Controls v8 framework and practical tips for protecting against cyber threats, keeping […]