Senior Security Engineer, Platform Security

Block builds simple, powerful tools that make progress towards an economy that’s truly open to all.

Each of our brands unlocks different aspects of the economy for more people. Square makes commerce and financial services accessible to sellers. Cash App is the easy way to spend, send, and store money. Afterpay is transforming the way customers manage their spending over time. TIDAL is a music platform that empowers artists to thrive as entrepreneurs. Bitkey is a simple self-custody wallet built for bitcoin. Proto is a suite of bitcoin mining products and services. Together, we’re helping build a financial system that is open to everyone. Join us.

The Role

The Platform Security team is responsible for securing Block's cloud, compute, and network infrastructure across multiple business units including Square, Cash, and Afterpay.

We discover, track, and enable the business to remediate the most critical security risks across Block's cloud ecosystems (AWS and GCP). We drive the creation of cloud security policy and best practices, measure and aggregate deviations from these policies, and develop capabilities to estimate security risk based on cloud signals and business context. This work drives Block's cloud security strategy and is the lens through which Block measures progress of our cloud security posture over time.

We believe that the secure option should be the easiest option for our users. We're looking for a strong Senior Platform Security Engineer with a deep understanding of securing cloud infrastructure and services at scale to help us execute on this vision.

You Will

• Build security guardrails across our infrastructure. Design and deploy controls for cloud resources, compute workloads, and network traffic across AWS, GCP, and hybrid environments.
• Strengthen cloud security. Improve IAM and organization-level policies, automate the discovery and prioritization of misconfigurations and sensitive data exposures, and evolve security exception workflows.
• Secure workloads from build to runtime. Improve Kubernetes and container isolation, protect CI/CD secrets and permissions, and strengthen image signing and software supply chain controls.
• Protect service connectivity. Develop network segmentation, ingress and egress policies, firewall controls, and edge protections that reduce exposure while supporting business needs.
• Write and operate production software. Build tested, maintainable services, integrations, and infrastructure-as-code that make security controls reliable and manageable at scale.
• Partner with platform and application teams to embed secure defaults into shared infrastructure and eliminate recurring categories of risk.
• Use security findings, operational telemetry, and business context to prioritize improvements and measure their effectiveness.
• Participate in the Platform Security on-call rotation, troubleshoot issues across infrastructure layers, and turn recurring support needs into automation and self-service capabilities.
• Lead projects from design through rollout, document technical decisions, and share expertise through mentoring and engineering reviews.

You Have

• 8+ years of experience as a software, infrastructure, or security engineer, including 4+ years securing production infrastructure at scale.
• Hands-on experience securing production infrastructure in AWS and/or GCP.
• Deep expertise in infrastructure security, with the ability to apply your knowledge across unfamiliar systems and technologies.
• A solid understanding of infrastructure security fundamentals, including least privilege, workload isolation, network segmentation, and secure service communication.
• Strong programming skills in Python, Go, or a similar language, with experience building and maintaining production tooling or services.
• Experience using Terraform or similar infrastructure-as-code tools to manage controls through reviewed, tested, and staged changes.
• Demonstrated ability to deliver complex projects and make practical tradeoffs between security risk, reliability, and developer experience.
• Clear communication and troubleshooting skills, including working with people outside security to resolve ambiguous problems.
• Experience using AI-assisted development tools in engineering workflows while taking responsibility for validating code, tests, and security implications.

Bonus If You Have

• Experience delivering security improvements that span multiple infrastructure layers and teams.
• Familiarity with cloud security posture management (CSPM), data security posture management (DSPM), security metrics, or automated exception workflows.
• Experience operating controls across large multi-account, multi-project, or shared Kubernetes environments.
• Experience supporting multiple business units with different infrastructure, compliance, and regulatory requirements

We’re working to build a more inclusive economy where our customers have equal access to opportunity, and we strive to live by these same values in building our workplace. Block is an equal opportunity employer evaluating all employees and job applicants without regard to identity or any legally protected class. We will consider qualified applicants with arrest or conviction records for employment in accordance with state and local laws and “fair chance” ordinances.

We believe in being fair, and are committed to an inclusive interview experience, including providing reasonable accommodations to disabled applicants throughout the recruitment process. We encourage applicants to share any needed accommodations with their recruiter, who will treat these requests as confidentially as possible. Want to learn more about what we’re doing to build a workplace that is fair and square? Check out our I+D page.

While there is no specific deadline to apply for this role, U.S. roles are typically open for an average of 55 days before being filled by a successful candidate. Please refer to the date listed at the top of this job page for when this role was first posted.