Full episode and show notes

Identity, IAM Technologies, Generative AI

The Agent Is the New Insider: Why Human Risk Doesn’t Stop at People – Leslie Nielsen – BH26 #1

AI agents now act with the same credentials and access as the humans who deployed them, but without the judgment or accountability that comes with actual employment. Mimecast CISO Leslie Nielsen argues that treating agentic AI as a brand new, standalone security category is the wrong instinct: agents are an extension of human risk, and the controls organizations already use to manage people are the right foundation for managing machines. In this conversation, Nielsen unpacks the growing gap between security leaders who expect AI driven attacks and those who feel prepared for them, and what that gap means for CISOs walking the floor at Black Hat. Segment Resources: Mimecast’s new whitepaper S...

August 5, 2026

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Full Segment Notes

AI agents now act with the same credentials and access as the humans who deployed them, but without the judgment or accountability that comes with actual employment. Mimecast CISO Leslie Nielsen argues that treating agentic AI as a brand new, standalone security category is the wrong instinct: agents are an extension of human risk, and the controls organizations already use to manage people are the right foundation for managing machines. In this conversation, Nielsen unpacks the growing gap between security leaders who expect AI driven attacks and those who feel prepared for them, and what that gap means for CISOs walking the floor at Black Hat.

Segment Resources:

Mimecast's new whitepaper Securing The Agentic Enterprise: https://assets.mimecast.com/api/public/content/securing-the-agentic-enterprise?v=ea66db05 Mimecast's landing page for thought leadership resources: https://www.workprotected.com/ Mimecast's State of Human Risk Report: https://www.mimecast.com/resources/ebooks/state-of-human-risk/ Mimecast's Threat Intelligence Hub: https://www.mimecast.com/threat-intelligence-hub/

For more information about Mimecast please visit: https://securityweekly.com/mimecastbh

Key Moments

0:00 - Introduction to Black Hat 2026 and Mimecast
0:21 - The Biggest Risks of AI Agents
01:48 - Shadow AI, Speed, and Agent Sprawl
03:02 - Managing Non-Human Identities
04:29 - Do We Need New Security Controls?
06:27 - AI Agents, Secrets, and Identity Management
08:31 - Helping CISOs Manage AI Risk
10:10 - Mimecast’s AI Security Solutions
11:23 - Training AI Agents Like Employees
13:16 - Extending Existing Security Controls to AI
14:02 - Treating AI Agents as Part of the Workforce
15:01 - Closing Remarks and Black Hat 2026 Coverage

Guest

Chief Information Security Officer at Mimecast

Leslie leads Mimecast’s global cybersecurity strategy as CISO, including threat intelligence, risk management, and detection and response, while ensuring regulatory compliance to protect Mimecast’s more than 42,000 global customers. With over 25 years of cybersecurity experience, he is known for driving innovative security strategies and building resilient, high-performing teams. He joined Mimecast from Klaviyo, where he served as SVP and CISO and helped scale the company to $1.3 billion in revenue, strengthen its security posture, and lead its security function through IPO. Before that, he was SVP and CISO at Nuance Communications, joining after a major malware attack to lead an accelerated security transformation that helped position the company as one of Microsoft’s largest acquisitions.

Earlier in his career, Leslie held senior security leadership roles at SAP Concur and SuccessFactors as VP and CISO, served as CTO at SOS Security, and held senior positions at IBM and ACS (acquired by Xerox); he has also served on Google’s CISO Cloud Advisory Board. Leslie holds a Bachelor of Science in Computer Science from Texas Tech University.

Host

https://dangerouserrors.com

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